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1!-------------------------------------------------------------------------------
2module module_gfs_funcphys
3!$$$  Module Documentation Block
4!
5! Module:    funcphys        API for basic thermodynamic physics
6!   Author: Iredell          Org: W/NX23     Date: 1999-03-01
7!
8! Abstract: This module provides an Application Program Interface
9!   for computing basic thermodynamic physics functions, in particular
10!     (1) saturation vapor pressure as a function of temperature,
11!     (2) dewpoint temperature as a function of vapor pressure,
12!     (3) equivalent potential temperature as a function of temperature
13!         and scaled pressure to the kappa power,
14!     (4) temperature and specific humidity along a moist adiabat
15!         as functions of equivalent potential temperature and
16!         scaled pressure to the kappa power,
17!     (5) scaled pressure to the kappa power as a function of pressure, and
18!     (6) temperature at the lifting condensation level as a function
19!         of temperature and dewpoint depression.
20!   The entry points required to set up lookup tables start with a "g".
21!   All the other entry points are functions starting with an "f" or
22!   are subroutines starting with an "s".  These other functions and
23!   subroutines are elemental; that is, they return a scalar if they
24!   are passed only scalars, but they return an array if they are passed
25!   an array.  These other functions and subroutines can be inlined, too.
26!   
27! Program History Log:
28!   1999-03-01  Mark Iredell
29!   1999-10-15  Mark Iredell  SI unit for pressure (Pascals)
30!   2001-02-26  Mark Iredell  Ice phase changes of Hong and Moorthi
31!
32! Public Variables:
33!   krealfp         Integer parameter kind or length of reals (=kind_phys)
34!
35! Public Subprograms:
36!   gpvsl            Compute saturation vapor pressure over liquid table
37!
38!   fpvsl           Elementally compute saturation vapor pressure over liquid
39!     function result Real(krealfp) saturation vapor pressure in Pascals
40!     t               Real(krealfp) temperature in Kelvin
41!
42!   fpvslq          Elementally compute saturation vapor pressure over liquid
43!     function result Real(krealfp) saturation vapor pressure in Pascals
44!     t               Real(krealfp) temperature in Kelvin
45!
46!   fpvslx          Elementally compute saturation vapor pressure over liquid
47!     function result Real(krealfp) saturation vapor pressure in Pascals
48!     t               Real(krealfp) temperature in Kelvin
49!
50!   gpvsi            Compute saturation vapor pressure over ice table
51!
52!   fpvsi           Elementally compute saturation vapor pressure over ice
53!     function result Real(krealfp) saturation vapor pressure in Pascals
54!     t               Real(krealfp) temperature in Kelvin
55!
56!   fpvsiq          Elementally compute saturation vapor pressure over ice
57!     function result Real(krealfp) saturation vapor pressure in Pascals
58!     t               Real(krealfp) temperature in Kelvin
59!
60!   fpvsix          Elementally compute saturation vapor pressure over ice
61!     function result Real(krealfp) saturation vapor pressure in Pascals
62!     t               Real(krealfp) temperature in Kelvin
63!
64!   gpvs            Compute saturation vapor pressure table
65!
66!   fpvs            Elementally compute saturation vapor pressure
67!     function result Real(krealfp) saturation vapor pressure in Pascals
68!     t               Real(krealfp) temperature in Kelvin
69!
70!   fpvsq           Elementally compute saturation vapor pressure
71!     function result Real(krealfp) saturation vapor pressure in Pascals
72!     t               Real(krealfp) temperature in Kelvin
73!
74!   fpvsx           Elementally compute saturation vapor pressure
75!     function result Real(krealfp) saturation vapor pressure in Pascals
76!     t               Real(krealfp) temperature in Kelvin
77!
78!   gtdpl           Compute dewpoint temperature over liquid table
79!
80!   ftdpl           Elementally compute dewpoint temperature over liquid
81!     function result Real(krealfp) dewpoint temperature in Kelvin
82!     pv              Real(krealfp) vapor pressure in Pascals
83!
84!   ftdplq          Elementally compute dewpoint temperature over liquid
85!     function result Real(krealfp) dewpoint temperature in Kelvin
86!     pv              Real(krealfp) vapor pressure in Pascals
87!
88!   ftdplx          Elementally compute dewpoint temperature over liquid
89!     function result Real(krealfp) dewpoint temperature in Kelvin
90!     pv              Real(krealfp) vapor pressure in Pascals
91!
92!   ftdplxg         Elementally compute dewpoint temperature over liquid
93!     function result Real(krealfp) dewpoint temperature in Kelvin
94!     t               Real(krealfp) guess dewpoint temperature in Kelvin
95!     pv              Real(krealfp) vapor pressure in Pascals
96!
97!   gtdpi           Compute dewpoint temperature table over ice
98!
99!   ftdpi           Elementally compute dewpoint temperature over ice
100!     function result Real(krealfp) dewpoint temperature in Kelvin
101!     pv              Real(krealfp) vapor pressure in Pascals
102!
103!   ftdpiq          Elementally compute dewpoint temperature over ice
104!     function result Real(krealfp) dewpoint temperature in Kelvin
105!     pv              Real(krealfp) vapor pressure in Pascals
106!
107!   ftdpix          Elementally compute dewpoint temperature over ice
108!     function result Real(krealfp) dewpoint temperature in Kelvin
109!     pv              Real(krealfp) vapor pressure in Pascals
110!
111!   ftdpixg         Elementally compute dewpoint temperature over ice
112!     function result Real(krealfp) dewpoint temperature in Kelvin
113!     t               Real(krealfp) guess dewpoint temperature in Kelvin
114!     pv              Real(krealfp) vapor pressure in Pascals
115!
116!   gtdp            Compute dewpoint temperature table
117!
118!   ftdp            Elementally compute dewpoint temperature
119!     function result Real(krealfp) dewpoint temperature in Kelvin
120!     pv              Real(krealfp) vapor pressure in Pascals
121!
122!   ftdpq           Elementally compute dewpoint temperature
123!     function result Real(krealfp) dewpoint temperature in Kelvin
124!     pv              Real(krealfp) vapor pressure in Pascals
125!
126!   ftdpx           Elementally compute dewpoint temperature
127!     function result Real(krealfp) dewpoint temperature in Kelvin
128!     pv              Real(krealfp) vapor pressure in Pascals
129!
130!   ftdpxg          Elementally compute dewpoint temperature
131!     function result Real(krealfp) dewpoint temperature in Kelvin
132!     t               Real(krealfp) guess dewpoint temperature in Kelvin
133!     pv              Real(krealfp) vapor pressure in Pascals
134!
135!   gthe            Compute equivalent potential temperature table
136!
137!   fthe            Elementally compute equivalent potential temperature
138!     function result Real(krealfp) equivalent potential temperature in Kelvin
139!     t               Real(krealfp) LCL temperature in Kelvin
140!     pk              Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
141!
142!   ftheq           Elementally compute equivalent potential temperature
143!     function result Real(krealfp) equivalent potential temperature in Kelvin
144!     t               Real(krealfp) LCL temperature in Kelvin
145!     pk              Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
146!
147!   fthex           Elementally compute equivalent potential temperature
148!     function result Real(krealfp) equivalent potential temperature in Kelvin
149!     t               Real(krealfp) LCL temperature in Kelvin
150!     pk              Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
151!
152!   gtma            Compute moist adiabat tables
153!
154!   stma            Elementally compute moist adiabat temperature and moisture
155!     the             Real(krealfp) equivalent potential temperature in Kelvin
156!     pk              Real(krealfp) pressure over 1e5 Pa to the kappa power
157!     tma             Real(krealfp) parcel temperature in Kelvin
158!     qma             Real(krealfp) parcel specific humidity in kg/kg
159!
160!   stmaq           Elementally compute moist adiabat temperature and moisture
161!     the             Real(krealfp) equivalent potential temperature in Kelvin
162!     pk              Real(krealfp) pressure over 1e5 Pa to the kappa power
163!     tma             Real(krealfp) parcel temperature in Kelvin
164!     qma             Real(krealfp) parcel specific humidity in kg/kg
165!
166!   stmax           Elementally compute moist adiabat temperature and moisture
167!     the             Real(krealfp) equivalent potential temperature in Kelvin
168!     pk              Real(krealfp) pressure over 1e5 Pa to the kappa power
169!     tma             Real(krealfp) parcel temperature in Kelvin
170!     qma             Real(krealfp) parcel specific humidity in kg/kg
171!
172!   stmaxg          Elementally compute moist adiabat temperature and moisture
173!     tg              Real(krealfp) guess parcel temperature in Kelvin
174!     the             Real(krealfp) equivalent potential temperature in Kelvin
175!     pk              Real(krealfp) pressure over 1e5 Pa to the kappa power
176!     tma             Real(krealfp) parcel temperature in Kelvin
177!     qma             Real(krealfp) parcel specific humidity in kg/kg
178!
179!   gpkap           Compute pressure to the kappa table
180!
181!   fpkap           Elementally raise pressure to the kappa power.
182!     function result Real(krealfp) p over 1e5 Pa to the kappa power
183!     p               Real(krealfp) pressure in Pascals
184!
185!   fpkapq          Elementally raise pressure to the kappa power.
186!     function result Real(krealfp) p over 1e5 Pa to the kappa power
187!     p               Real(krealfp) pressure in Pascals
188!
189!   fpkapo          Elementally raise pressure to the kappa power.
190!     function result Real(krealfp) p over 1e5 Pa to the kappa power
191!     p               Real(krealfp) surface pressure in Pascals
192!
193!   fpkapx          Elementally raise pressure to the kappa power.
194!     function result Real(krealfp) p over 1e5 Pa to the kappa power
195!     p               Real(krealfp) pressure in Pascals
196!
197!   grkap           Compute pressure to the 1/kappa table
198!
199!   frkap           Elementally raise pressure to the 1/kappa power.
200!     function result Real(krealfp) pressure in Pascals
201!     pkap            Real(krealfp) p over 1e5 Pa to the 1/kappa power
202!
203!   frkapq          Elementally raise pressure to the kappa power.
204!     function result Real(krealfp) pressure in Pascals
205!     pkap            Real(krealfp) p over 1e5 Pa to the kappa power
206!
207!   frkapx          Elementally raise pressure to the kappa power.
208!     function result Real(krealfp) pressure in Pascals
209!     pkap            Real(krealfp) p over 1e5 Pa to the kappa power
210!
211!   gtlcl           Compute LCL temperature table
212!
213!   ftlcl           Elementally compute LCL temperature.
214!     function result Real(krealfp) temperature at the LCL in Kelvin
215!     t               Real(krealfp) temperature in Kelvin
216!     tdpd            Real(krealfp) dewpoint depression in Kelvin
217!
218!   ftlclq          Elementally compute LCL temperature.
219!     function result Real(krealfp) temperature at the LCL in Kelvin
220!     t               Real(krealfp) temperature in Kelvin
221!     tdpd            Real(krealfp) dewpoint depression in Kelvin
222!
223!   ftlclo          Elementally compute LCL temperature.
224!     function result Real(krealfp) temperature at the LCL in Kelvin
225!     t               Real(krealfp) temperature in Kelvin
226!     tdpd            Real(krealfp) dewpoint depression in Kelvin
227!
228!   ftlclx          Elementally compute LCL temperature.
229!     function result Real(krealfp) temperature at the LCL in Kelvin
230!     t               Real(krealfp) temperature in Kelvin
231!     tdpd            Real(krealfp) dewpoint depression in Kelvin
232!
233!   gfuncphys       Compute all physics function tables
234!
235! Attributes:
236!   Language: Fortran 90
237!
238!$$$
239  use module_gfs_machine,only:kind_phys
240  use module_gfs_physcons
241  implicit none
242  private
243! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
244! Public Variables
245! integer,public,parameter:: krealfp=selected_real_kind(15,45)
246  integer,public,parameter:: krealfp=kind_phys
247! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
248! Private Variables
249  real(krealfp),parameter:: psatb=con_psat*1.e-5
250  integer,parameter:: nxpvsl=7501
251  real(krealfp) c1xpvsl,c2xpvsl,tbpvsl(nxpvsl)
252  integer,parameter:: nxpvsi=7501
253  real(krealfp) c1xpvsi,c2xpvsi,tbpvsi(nxpvsi)
254  integer,parameter:: nxpvs=7501
255  real(krealfp) c1xpvs,c2xpvs,tbpvs(nxpvs)
256  integer,parameter:: nxtdpl=5001
257  real(krealfp) c1xtdpl,c2xtdpl,tbtdpl(nxtdpl)
258  integer,parameter:: nxtdpi=5001
259  real(krealfp) c1xtdpi,c2xtdpi,tbtdpi(nxtdpi)
260  integer,parameter:: nxtdp=5001
261  real(krealfp) c1xtdp,c2xtdp,tbtdp(nxtdp)
262  integer,parameter:: nxthe=241,nythe=151
263  real(krealfp) c1xthe,c2xthe,c1ythe,c2ythe,tbthe(nxthe,nythe)
264  integer,parameter:: nxma=151,nyma=121
265  real(krealfp) c1xma,c2xma,c1yma,c2yma,tbtma(nxma,nyma),tbqma(nxma,nyma)
266! integer,parameter:: nxpkap=5501
267  integer,parameter:: nxpkap=11001
268  real(krealfp) c1xpkap,c2xpkap,tbpkap(nxpkap)
269  integer,parameter:: nxrkap=5501
270  real(krealfp) c1xrkap,c2xrkap,tbrkap(nxrkap)
271  integer,parameter:: nxtlcl=151,nytlcl=61
272  real(krealfp) c1xtlcl,c2xtlcl,c1ytlcl,c2ytlcl,tbtlcl(nxtlcl,nytlcl)
273! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
274! Public Subprograms
275  public gpvsl,fpvsl,fpvslq,fpvslx
276  public gpvsi,fpvsi,fpvsiq,fpvsix
277  public gpvs,fpvs,fpvsq,fpvsx
278  public gtdpl,ftdpl,ftdplq,ftdplx,ftdplxg
279  public gtdpi,ftdpi,ftdpiq,ftdpix,ftdpixg
280  public gtdp,ftdp,ftdpq,ftdpx,ftdpxg
281  public gthe,fthe,ftheq,fthex
282  public gtma,stma,stmaq,stmax,stmaxg
283  public gpkap,fpkap,fpkapq,fpkapo,fpkapx
284  public grkap,frkap,frkapq,frkapx
285  public gtlcl,ftlcl,ftlclq,ftlclo,ftlclx
286  public gfuncphys
287contains
288!-------------------------------------------------------------------------------
289  subroutine gpvsl
290!$$$     Subprogram Documentation Block
291!
292! Subprogram: gpvsl        Compute saturation vapor pressure table over liquid
293!   Author: N Phillips            W/NMC2X2   Date: 30 dec 82
294!
295! Abstract: Computes saturation vapor pressure table as a function of
296!   temperature for the table lookup function fpvsl.
297!   Exact saturation vapor pressures are calculated in subprogram fpvslx.
298!   The current implementation computes a table with a length
299!   of 7501 for temperatures ranging from 180. to 330. Kelvin.
300!
301! Program History Log:
302!   91-05-07  Iredell
303!   94-12-30  Iredell             expand table
304! 1999-03-01  Iredell             f90 module
305!
306! Usage:  call gpvsl
307!
308! Subprograms called:
309!   (fpvslx)   inlinable function to compute saturation vapor pressure
310!
311! Attributes:
312!   Language: Fortran 90.
313!
314!$$$
315    implicit none
316    integer jx
317    real(krealfp) xmin,xmax,xinc,x,t
318! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
319    xmin=180.0_krealfp
320    xmax=330.0_krealfp
321    xinc=(xmax-xmin)/(nxpvsl-1)
322!   c1xpvsl=1.-xmin/xinc
323    c2xpvsl=1./xinc
324    c1xpvsl=1.-xmin*c2xpvsl
325    do jx=1,nxpvsl
326      x=xmin+(jx-1)*xinc
327      t=x
328      tbpvsl(jx)=fpvslx(t)
329    enddo
330! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
331  end subroutine
332!-------------------------------------------------------------------------------
333! elemental function fpvsl(t)
334  function fpvsl(t)
335!$$$     Subprogram Documentation Block
336!
337! Subprogram: fpvsl        Compute saturation vapor pressure over liquid
338!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
339!
340! Abstract: Compute saturation vapor pressure from the temperature.
341!   A linear interpolation is done between values in a lookup table
342!   computed in gpvsl. See documentation for fpvslx for details.
343!   Input values outside table range are reset to table extrema.
344!   The interpolation accuracy is almost 6 decimal places.
345!   On the Cray, fpvsl is about 4 times faster than exact calculation.
346!   This function should be expanded inline in the calling routine.
347!
348! Program History Log:
349!   91-05-07  Iredell             made into inlinable function
350!   94-12-30  Iredell             expand table
351! 1999-03-01  Iredell             f90 module
352!
353! Usage:   pvsl=fpvsl(t)
354!
355!   Input argument list:
356!     t          Real(krealfp) temperature in Kelvin
357!
358!   Output argument list:
359!     fpvsl      Real(krealfp) saturation vapor pressure in Pascals
360!
361! Attributes:
362!   Language: Fortran 90.
363!
364!$$$
365    implicit none
366    real(krealfp) fpvsl
367    real(krealfp),intent(in):: t
368    integer jx
369    real(krealfp) xj
370! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
371    xj=min(max(c1xpvsl+c2xpvsl*t,1._krealfp),real(nxpvsl,krealfp))
372    jx=min(xj,nxpvsl-1._krealfp)
373    fpvsl=tbpvsl(jx)+(xj-jx)*(tbpvsl(jx+1)-tbpvsl(jx))
374! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
375  end function
376!-------------------------------------------------------------------------------
377! elemental function fpvslq(t)
378  function fpvslq(t)
379!$$$     Subprogram Documentation Block
380!
381! Subprogram: fpvslq       Compute saturation vapor pressure over liquid
382!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
383!
384! Abstract: Compute saturation vapor pressure from the temperature.
385!   A quadratic interpolation is done between values in a lookup table
386!   computed in gpvsl. See documentation for fpvslx for details.
387!   Input values outside table range are reset to table extrema.
388!   The interpolation accuracy is almost 9 decimal places.
389!   On the Cray, fpvslq is about 3 times faster than exact calculation.
390!   This function should be expanded inline in the calling routine.
391!
392! Program History Log:
393!   91-05-07  Iredell             made into inlinable function
394!   94-12-30  Iredell             quadratic interpolation
395! 1999-03-01  Iredell             f90 module
396!
397! Usage:   pvsl=fpvslq(t)
398!
399!   Input argument list:
400!     t          Real(krealfp) temperature in Kelvin
401!
402!   Output argument list:
403!     fpvslq     Real(krealfp) saturation vapor pressure in Pascals
404!
405! Attributes:
406!   Language: Fortran 90.
407!
408!$$$
409    implicit none
410    real(krealfp) fpvslq
411    real(krealfp),intent(in):: t
412    integer jx
413    real(krealfp) xj,dxj,fj1,fj2,fj3
414! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
415    xj=min(max(c1xpvsl+c2xpvsl*t,1._krealfp),real(nxpvsl,krealfp))
416    jx=min(max(nint(xj),2),nxpvsl-1)
417    dxj=xj-jx
418    fj1=tbpvsl(jx-1)
419    fj2=tbpvsl(jx)
420    fj3=tbpvsl(jx+1)
421    fpvslq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
422! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
423  end function
424!-------------------------------------------------------------------------------
425! elemental function fpvslx(t)
426  function fpvslx(t)
427!$$$     Subprogram Documentation Block
428!
429! Subprogram: fpvslx       Compute saturation vapor pressure over liquid
430!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
431!
432! Abstract: Exactly compute saturation vapor pressure from temperature.
433!   The water model assumes a perfect gas, constant specific heats
434!   for gas and liquid, and neglects the volume of the liquid.
435!   The model does account for the variation of the latent heat
436!   of condensation with temperature.  The ice option is not included.
437!   The Clausius-Clapeyron equation is integrated from the triple point
438!   to get the formula
439!       pvsl=con_psat*(tr**xa)*exp(xb*(1.-tr))
440!   where tr is ttp/t and other values are physical constants.
441!   This function should be expanded inline in the calling routine.
442!
443! Program History Log:
444!   91-05-07  Iredell             made into inlinable function
445!   94-12-30  Iredell             exact computation
446! 1999-03-01  Iredell             f90 module
447!
448! Usage:   pvsl=fpvslx(t)
449!
450!   Input argument list:
451!     t          Real(krealfp) temperature in Kelvin
452!
453!   Output argument list:
454!     fpvslx     Real(krealfp) saturation vapor pressure in Pascals
455!
456! Attributes:
457!   Language: Fortran 90.
458!
459!$$$
460    implicit none
461    real(krealfp) fpvslx
462    real(krealfp),intent(in):: t
463    real(krealfp),parameter:: dldt=con_cvap-con_cliq
464    real(krealfp),parameter:: heat=con_hvap
465    real(krealfp),parameter:: xpona=-dldt/con_rv
466    real(krealfp),parameter:: xponb=-dldt/con_rv+heat/(con_rv*con_ttp)
467    real(krealfp) tr
468! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
469    tr=con_ttp/t
470    fpvslx=con_psat*(tr**xpona)*exp(xponb*(1.-tr))
471! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
472  end function
473!-------------------------------------------------------------------------------
474  subroutine gpvsi
475!$$$     Subprogram Documentation Block
476!
477! Subprogram: gpvsi        Compute saturation vapor pressure table over ice
478!   Author: N Phillips            W/NMC2X2   Date: 30 dec 82
479!
480! Abstract: Computes saturation vapor pressure table as a function of
481!   temperature for the table lookup function fpvsi.
482!   Exact saturation vapor pressures are calculated in subprogram fpvsix.
483!   The current implementation computes a table with a length
484!   of 7501 for temperatures ranging from 180. to 330. Kelvin.
485!
486! Program History Log:
487!   91-05-07  Iredell
488!   94-12-30  Iredell             expand table
489! 1999-03-01  Iredell             f90 module
490! 2001-02-26  Iredell             ice phase
491!
492! Usage:  call gpvsi
493!
494! Subprograms called:
495!   (fpvsix)   inlinable function to compute saturation vapor pressure
496!
497! Attributes:
498!   Language: Fortran 90.
499!
500!$$$
501    implicit none
502    integer jx
503    real(krealfp) xmin,xmax,xinc,x,t
504! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
505    xmin=180.0_krealfp
506    xmax=330.0_krealfp
507    xinc=(xmax-xmin)/(nxpvsi-1)
508!   c1xpvsi=1.-xmin/xinc
509    c2xpvsi=1./xinc
510    c1xpvsi=1.-xmin*c2xpvsi
511    do jx=1,nxpvsi
512      x=xmin+(jx-1)*xinc
513      t=x
514      tbpvsi(jx)=fpvsix(t)
515    enddo
516! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
517  end subroutine
518!-------------------------------------------------------------------------------
519! elemental function fpvsi(t)
520  function fpvsi(t)
521!$$$     Subprogram Documentation Block
522!
523! Subprogram: fpvsi        Compute saturation vapor pressure over ice
524!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
525!
526! Abstract: Compute saturation vapor pressure from the temperature.
527!   A linear interpolation is done between values in a lookup table
528!   computed in gpvsi. See documentation for fpvsix for details.
529!   Input values outside table range are reset to table extrema.
530!   The interpolation accuracy is almost 6 decimal places.
531!   On the Cray, fpvsi is about 4 times faster than exact calculation.
532!   This function should be expanded inline in the calling routine.
533!
534! Program History Log:
535!   91-05-07  Iredell             made into inlinable function
536!   94-12-30  Iredell             expand table
537! 1999-03-01  Iredell             f90 module
538! 2001-02-26  Iredell             ice phase
539!
540! Usage:   pvsi=fpvsi(t)
541!
542!   Input argument list:
543!     t          Real(krealfp) temperature in Kelvin
544!
545!   Output argument list:
546!     fpvsi      Real(krealfp) saturation vapor pressure in Pascals
547!
548! Attributes:
549!   Language: Fortran 90.
550!
551!$$$
552    implicit none
553    real(krealfp) fpvsi
554    real(krealfp),intent(in):: t
555    integer jx
556    real(krealfp) xj
557! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
558    xj=min(max(c1xpvsi+c2xpvsi*t,1._krealfp),real(nxpvsi,krealfp))
559    jx=min(xj,nxpvsi-1._krealfp)
560    fpvsi=tbpvsi(jx)+(xj-jx)*(tbpvsi(jx+1)-tbpvsi(jx))
561! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
562  end function
563!-------------------------------------------------------------------------------
564! elemental function fpvsiq(t)
565  function fpvsiq(t)
566!$$$     Subprogram Documentation Block
567!
568! Subprogram: fpvsiq       Compute saturation vapor pressure over ice
569!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
570!
571! Abstract: Compute saturation vapor pressure from the temperature.
572!   A quadratic interpolation is done between values in a lookup table
573!   computed in gpvsi. See documentation for fpvsix for details.
574!   Input values outside table range are reset to table extrema.
575!   The interpolation accuracy is almost 9 decimal places.
576!   On the Cray, fpvsiq is about 3 times faster than exact calculation.
577!   This function should be expanded inline in the calling routine.
578!
579! Program History Log:
580!   91-05-07  Iredell             made into inlinable function
581!   94-12-30  Iredell             quadratic interpolation
582! 1999-03-01  Iredell             f90 module
583! 2001-02-26  Iredell             ice phase
584!
585! Usage:   pvsi=fpvsiq(t)
586!
587!   Input argument list:
588!     t          Real(krealfp) temperature in Kelvin
589!
590!   Output argument list:
591!     fpvsiq     Real(krealfp) saturation vapor pressure in Pascals
592!
593! Attributes:
594!   Language: Fortran 90.
595!
596!$$$
597    implicit none
598    real(krealfp) fpvsiq
599    real(krealfp),intent(in):: t
600    integer jx
601    real(krealfp) xj,dxj,fj1,fj2,fj3
602! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
603    xj=min(max(c1xpvsi+c2xpvsi*t,1._krealfp),real(nxpvsi,krealfp))
604    jx=min(max(nint(xj),2),nxpvsi-1)
605    dxj=xj-jx
606    fj1=tbpvsi(jx-1)
607    fj2=tbpvsi(jx)
608    fj3=tbpvsi(jx+1)
609    fpvsiq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
610! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
611  end function
612!-------------------------------------------------------------------------------
613! elemental function fpvsix(t)
614  function fpvsix(t)
615!$$$     Subprogram Documentation Block
616!
617! Subprogram: fpvsix       Compute saturation vapor pressure over ice
618!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
619!
620! Abstract: Exactly compute saturation vapor pressure from temperature.
621!   The water model assumes a perfect gas, constant specific heats
622!   for gas and ice, and neglects the volume of the ice.
623!   The model does account for the variation of the latent heat
624!   of condensation with temperature.  The liquid option is not included.
625!   The Clausius-Clapeyron equation is integrated from the triple point
626!   to get the formula
627!       pvsi=con_psat*(tr**xa)*exp(xb*(1.-tr))
628!   where tr is ttp/t and other values are physical constants.
629!   This function should be expanded inline in the calling routine.
630!
631! Program History Log:
632!   91-05-07  Iredell             made into inlinable function
633!   94-12-30  Iredell             exact computation
634! 1999-03-01  Iredell             f90 module
635! 2001-02-26  Iredell             ice phase
636!
637! Usage:   pvsi=fpvsix(t)
638!
639!   Input argument list:
640!     t          Real(krealfp) temperature in Kelvin
641!
642!   Output argument list:
643!     fpvsix     Real(krealfp) saturation vapor pressure in Pascals
644!
645! Attributes:
646!   Language: Fortran 90.
647!
648!$$$
649    implicit none
650    real(krealfp) fpvsix
651    real(krealfp),intent(in):: t
652    real(krealfp),parameter:: dldt=con_cvap-con_csol
653    real(krealfp),parameter:: heat=con_hvap+con_hfus
654    real(krealfp),parameter:: xpona=-dldt/con_rv
655    real(krealfp),parameter:: xponb=-dldt/con_rv+heat/(con_rv*con_ttp)
656    real(krealfp) tr
657! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
658    tr=con_ttp/t
659    fpvsix=con_psat*(tr**xpona)*exp(xponb*(1.-tr))
660! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
661  end function
662!-------------------------------------------------------------------------------
663  subroutine gpvs
664!$$$     Subprogram Documentation Block
665!
666! Subprogram: gpvs         Compute saturation vapor pressure table
667!   Author: N Phillips            W/NMC2X2   Date: 30 dec 82
668!
669! Abstract: Computes saturation vapor pressure table as a function of
670!   temperature for the table lookup function fpvs.
671!   Exact saturation vapor pressures are calculated in subprogram fpvsx.
672!   The current implementation computes a table with a length
673!   of 7501 for temperatures ranging from 180. to 330. Kelvin.
674!
675! Program History Log:
676!   91-05-07  Iredell
677!   94-12-30  Iredell             expand table
678! 1999-03-01  Iredell             f90 module
679! 2001-02-26  Iredell             ice phase
680!
681! Usage:  call gpvs
682!
683! Subprograms called:
684!   (fpvsx)    inlinable function to compute saturation vapor pressure
685!
686! Attributes:
687!   Language: Fortran 90.
688!
689!$$$
690    implicit none
691    integer jx
692    real(krealfp) xmin,xmax,xinc,x,t
693! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
694    xmin=180.0_krealfp
695    xmax=330.0_krealfp
696    xinc=(xmax-xmin)/(nxpvs-1)
697!   c1xpvs=1.-xmin/xinc
698    c2xpvs=1./xinc
699    c1xpvs=1.-xmin*c2xpvs
700    do jx=1,nxpvs
701      x=xmin+(jx-1)*xinc
702      t=x
703      tbpvs(jx)=fpvsx(t)
704    enddo
705! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
706  end subroutine
707!-------------------------------------------------------------------------------
708! elemental function fpvs(t)
709  function fpvs(t)
710!$$$     Subprogram Documentation Block
711!
712! Subprogram: fpvs         Compute saturation vapor pressure
713!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
714!
715! Abstract: Compute saturation vapor pressure from the temperature.
716!   A linear interpolation is done between values in a lookup table
717!   computed in gpvs. See documentation for fpvsx for details.
718!   Input values outside table range are reset to table extrema.
719!   The interpolation accuracy is almost 6 decimal places.
720!   On the Cray, fpvs is about 4 times faster than exact calculation.
721!   This function should be expanded inline in the calling routine.
722!
723! Program History Log:
724!   91-05-07  Iredell             made into inlinable function
725!   94-12-30  Iredell             expand table
726! 1999-03-01  Iredell             f90 module
727! 2001-02-26  Iredell             ice phase
728!
729! Usage:   pvs=fpvs(t)
730!
731!   Input argument list:
732!     t          Real(krealfp) temperature in Kelvin
733!
734!   Output argument list:
735!     fpvs       Real(krealfp) saturation vapor pressure in Pascals
736!
737! Attributes:
738!   Language: Fortran 90.
739!
740!$$$
741    implicit none
742    real(krealfp) fpvs
743    real(krealfp),intent(in):: t
744    integer jx
745    real(krealfp) xj
746! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
747    xj=min(max(c1xpvs+c2xpvs*t,1._krealfp),real(nxpvs,krealfp))
748    jx=min(xj,nxpvs-1._krealfp)
749    fpvs=tbpvs(jx)+(xj-jx)*(tbpvs(jx+1)-tbpvs(jx))
750! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
751  end function
752!-------------------------------------------------------------------------------
753! elemental function fpvsq(t)
754  function fpvsq(t)
755!$$$     Subprogram Documentation Block
756!
757! Subprogram: fpvsq        Compute saturation vapor pressure
758!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
759!
760! Abstract: Compute saturation vapor pressure from the temperature.
761!   A quadratic interpolation is done between values in a lookup table
762!   computed in gpvs. See documentation for fpvsx for details.
763!   Input values outside table range are reset to table extrema.
764!   The interpolation accuracy is almost 9 decimal places.
765!   On the Cray, fpvsq is about 3 times faster than exact calculation.
766!   This function should be expanded inline in the calling routine.
767!
768! Program History Log:
769!   91-05-07  Iredell             made into inlinable function
770!   94-12-30  Iredell             quadratic interpolation
771! 1999-03-01  Iredell             f90 module
772! 2001-02-26  Iredell             ice phase
773!
774! Usage:   pvs=fpvsq(t)
775!
776!   Input argument list:
777!     t          Real(krealfp) temperature in Kelvin
778!
779!   Output argument list:
780!     fpvsq      Real(krealfp) saturation vapor pressure in Pascals
781!
782! Attributes:
783!   Language: Fortran 90.
784!
785!$$$
786    implicit none
787    real(krealfp) fpvsq
788    real(krealfp),intent(in):: t
789    integer jx
790    real(krealfp) xj,dxj,fj1,fj2,fj3
791! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
792    xj=min(max(c1xpvs+c2xpvs*t,1._krealfp),real(nxpvs,krealfp))
793    jx=min(max(nint(xj),2),nxpvs-1)
794    dxj=xj-jx
795    fj1=tbpvs(jx-1)
796    fj2=tbpvs(jx)
797    fj3=tbpvs(jx+1)
798    fpvsq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
799! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
800  end function
801!-------------------------------------------------------------------------------
802! elemental function fpvsx(t)
803  function fpvsx(t)
804!$$$     Subprogram Documentation Block
805!
806! Subprogram: fpvsx        Compute saturation vapor pressure
807!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
808!
809! Abstract: Exactly compute saturation vapor pressure from temperature.
810!   The saturation vapor pressure over either liquid and ice is computed
811!   over liquid for temperatures above the triple point,
812!   over ice for temperatures 20 degress below the triple point,
813!   and a linear combination of the two for temperatures in between.
814!   The water model assumes a perfect gas, constant specific heats
815!   for gas, liquid and ice, and neglects the volume of the condensate.
816!   The model does account for the variation of the latent heat
817!   of condensation and sublimation with temperature.
818!   The Clausius-Clapeyron equation is integrated from the triple point
819!   to get the formula
820!       pvsl=con_psat*(tr**xa)*exp(xb*(1.-tr))
821!   where tr is ttp/t and other values are physical constants.
822!   The reference for this computation is Emanuel(1994), pages 116-117.
823!   This function should be expanded inline in the calling routine.
824!
825! Program History Log:
826!   91-05-07  Iredell             made into inlinable function
827!   94-12-30  Iredell             exact computation
828! 1999-03-01  Iredell             f90 module
829! 2001-02-26  Iredell             ice phase
830!
831! Usage:   pvs=fpvsx(t)
832!
833!   Input argument list:
834!     t          Real(krealfp) temperature in Kelvin
835!
836!   Output argument list:
837!     fpvsx      Real(krealfp) saturation vapor pressure in Pascals
838!
839! Attributes:
840!   Language: Fortran 90.
841!
842!$$$
843    implicit none
844    real(krealfp) fpvsx
845    real(krealfp),intent(in):: t
846    real(krealfp),parameter:: tliq=con_ttp
847    real(krealfp),parameter:: tice=con_ttp-20.0
848    real(krealfp),parameter:: dldtl=con_cvap-con_cliq
849    real(krealfp),parameter:: heatl=con_hvap
850    real(krealfp),parameter:: xponal=-dldtl/con_rv
851    real(krealfp),parameter:: xponbl=-dldtl/con_rv+heatl/(con_rv*con_ttp)
852    real(krealfp),parameter:: dldti=con_cvap-con_csol
853    real(krealfp),parameter:: heati=con_hvap+con_hfus
854    real(krealfp),parameter:: xponai=-dldti/con_rv
855    real(krealfp),parameter:: xponbi=-dldti/con_rv+heati/(con_rv*con_ttp)
856    real(krealfp) tr,w,pvl,pvi
857! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
858    tr=con_ttp/t
859    if(t.ge.tliq) then
860      fpvsx=con_psat*(tr**xponal)*exp(xponbl*(1.-tr))
861    elseif(t.lt.tice) then
862      fpvsx=con_psat*(tr**xponai)*exp(xponbi*(1.-tr))
863    else
864      w=(t-tice)/(tliq-tice)
865      pvl=con_psat*(tr**xponal)*exp(xponbl*(1.-tr))
866      pvi=con_psat*(tr**xponai)*exp(xponbi*(1.-tr))
867      fpvsx=w*pvl+(1.-w)*pvi
868    endif
869! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
870  end function
871!-------------------------------------------------------------------------------
872  subroutine gtdpl
873!$$$     Subprogram Documentation Block
874!
875! Subprogram: gtdpl        Compute dewpoint temperature over liquid table
876!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
877!
878! Abstract: Compute dewpoint temperature table as a function of
879!   vapor pressure for inlinable function ftdpl.
880!   Exact dewpoint temperatures are calculated in subprogram ftdplxg.
881!   The current implementation computes a table with a length
882!   of 5001 for vapor pressures ranging from 1 to 10001 Pascals
883!   giving a dewpoint temperature range of 208 to 319 Kelvin.
884!
885! Program History Log:
886!   91-05-07  Iredell
887!   94-12-30  Iredell             expand table
888! 1999-03-01  Iredell             f90 module
889!
890! Usage:  call gtdpl
891!
892! Subprograms called:
893!   (ftdplxg)  inlinable function to compute dewpoint temperature over liquid
894!
895! Attributes:
896!   Language: Fortran 90.
897!
898!$$$
899    implicit none
900    integer jx
901    real(krealfp) xmin,xmax,xinc,t,x,pv
902! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
903    xmin=1
904    xmax=10001
905    xinc=(xmax-xmin)/(nxtdpl-1)
906    c1xtdpl=1.-xmin/xinc
907    c2xtdpl=1./xinc
908    t=208.0
909    do jx=1,nxtdpl
910      x=xmin+(jx-1)*xinc
911      pv=x
912      t=ftdplxg(t,pv)
913      tbtdpl(jx)=t
914    enddo
915! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
916  end subroutine
917!-------------------------------------------------------------------------------
918! elemental function ftdpl(pv)
919  function ftdpl(pv)
920!$$$     Subprogram Documentation Block
921!
922! Subprogram: ftdpl        Compute dewpoint temperature over liquid
923!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
924!
925! Abstract: Compute dewpoint temperature from vapor pressure.
926!   A linear interpolation is done between values in a lookup table
927!   computed in gtdpl. See documentation for ftdplxg for details.
928!   Input values outside table range are reset to table extrema.
929!   The interpolation accuracy is better than 0.0005 Kelvin
930!   for dewpoint temperatures greater than 250 Kelvin,
931!   but decreases to 0.02 Kelvin for a dewpoint around 230 Kelvin.
932!   On the Cray, ftdpl is about 75 times faster than exact calculation.
933!   This function should be expanded inline in the calling routine.
934!
935! Program History Log:
936!   91-05-07  Iredell             made into inlinable function
937!   94-12-30  Iredell             expand table
938! 1999-03-01  Iredell             f90 module
939!
940! Usage:   tdpl=ftdpl(pv)
941!
942!   Input argument list:
943!     pv         Real(krealfp) vapor pressure in Pascals
944!
945!   Output argument list:
946!     ftdpl      Real(krealfp) dewpoint temperature in Kelvin
947!
948! Attributes:
949!   Language: Fortran 90.
950!
951!$$$
952    implicit none
953    real(krealfp) ftdpl
954    real(krealfp),intent(in):: pv
955    integer jx
956    real(krealfp) xj
957! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
958    xj=min(max(c1xtdpl+c2xtdpl*pv,1._krealfp),real(nxtdpl,krealfp))
959    jx=min(xj,nxtdpl-1._krealfp)
960    ftdpl=tbtdpl(jx)+(xj-jx)*(tbtdpl(jx+1)-tbtdpl(jx))
961! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
962  end function
963!-------------------------------------------------------------------------------
964! elemental function ftdplq(pv)
965  function ftdplq(pv)
966!$$$     Subprogram Documentation Block
967!
968! Subprogram: ftdplq       Compute dewpoint temperature over liquid
969!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
970!
971! Abstract: Compute dewpoint temperature from vapor pressure.
972!   A quadratic interpolation is done between values in a lookup table
973!   computed in gtdpl. see documentation for ftdplxg for details.
974!   Input values outside table range are reset to table extrema.
975!   the interpolation accuracy is better than 0.00001 Kelvin
976!   for dewpoint temperatures greater than 250 Kelvin,
977!   but decreases to 0.002 Kelvin for a dewpoint around 230 Kelvin.
978!   On the Cray, ftdplq is about 60 times faster than exact calculation.
979!   This function should be expanded inline in the calling routine.
980!
981! Program History Log:
982!   91-05-07  Iredell             made into inlinable function
983!   94-12-30  Iredell             quadratic interpolation
984! 1999-03-01  Iredell             f90 module
985!
986! Usage:   tdpl=ftdplq(pv)
987!
988!   Input argument list:
989!     pv         Real(krealfp) vapor pressure in Pascals
990!
991!   Output argument list:
992!     ftdplq     Real(krealfp) dewpoint temperature in Kelvin
993!
994! Attributes:
995!   Language: Fortran 90.
996!
997!$$$
998    implicit none
999    real(krealfp) ftdplq
1000    real(krealfp),intent(in):: pv
1001    integer jx
1002    real(krealfp) xj,dxj,fj1,fj2,fj3
1003! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1004    xj=min(max(c1xtdpl+c2xtdpl*pv,1._krealfp),real(nxtdpl,krealfp))
1005    jx=min(max(nint(xj),2),nxtdpl-1)
1006    dxj=xj-jx
1007    fj1=tbtdpl(jx-1)
1008    fj2=tbtdpl(jx)
1009    fj3=tbtdpl(jx+1)
1010    ftdplq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
1011! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1012  end function
1013!-------------------------------------------------------------------------------
1014! elemental function ftdplx(pv)
1015  function ftdplx(pv)
1016!$$$     Subprogram Documentation Block
1017!
1018! Subprogram: ftdplx       Compute dewpoint temperature over liquid
1019!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1020!
1021! Abstract: exactly compute dewpoint temperature from vapor pressure.
1022!   An approximate dewpoint temperature for function ftdplxg
1023!   is obtained using ftdpl so gtdpl must be already called.
1024!   See documentation for ftdplxg for details.
1025!
1026! Program History Log:
1027!   91-05-07  Iredell             made into inlinable function
1028!   94-12-30  Iredell             exact computation
1029! 1999-03-01  Iredell             f90 module
1030!
1031! Usage:   tdpl=ftdplx(pv)
1032!
1033!   Input argument list:
1034!     pv         Real(krealfp) vapor pressure in Pascals
1035!
1036!   Output argument list:
1037!     ftdplx     Real(krealfp) dewpoint temperature in Kelvin
1038!
1039! Subprograms called:
1040!   (ftdpl)    inlinable function to compute dewpoint temperature over liquid
1041!   (ftdplxg)  inlinable function to compute dewpoint temperature over liquid
1042!
1043! Attributes:
1044!   Language: Fortran 90.
1045!
1046!$$$
1047    implicit none
1048    real(krealfp) ftdplx
1049    real(krealfp),intent(in):: pv
1050    real(krealfp) tg
1051! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1052    tg=ftdpl(pv)
1053    ftdplx=ftdplxg(tg,pv)
1054! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1055  end function
1056!-------------------------------------------------------------------------------
1057! elemental function ftdplxg(tg,pv)
1058  function ftdplxg(tg,pv)
1059!$$$     Subprogram Documentation Block
1060!
1061! Subprogram: ftdplxg      Compute dewpoint temperature over liquid
1062!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1063!
1064! Abstract: Exactly compute dewpoint temperature from vapor pressure.
1065!   A guess dewpoint temperature must be provided.
1066!   The water model assumes a perfect gas, constant specific heats
1067!   for gas and liquid, and neglects the volume of the liquid.
1068!   The model does account for the variation of the latent heat
1069!   of condensation with temperature.  The ice option is not included.
1070!   The Clausius-Clapeyron equation is integrated from the triple point
1071!   to get the formula
1072!       pvs=con_psat*(tr**xa)*exp(xb*(1.-tr))
1073!   where tr is ttp/t and other values are physical constants.
1074!   The formula is inverted by iterating Newtonian approximations
1075!   for each pvs until t is found to within 1.e-6 Kelvin.
1076!   This function can be expanded inline in the calling routine.
1077!
1078! Program History Log:
1079!   91-05-07  Iredell             made into inlinable function
1080!   94-12-30  Iredell             exact computation
1081! 1999-03-01  Iredell             f90 module
1082!
1083! Usage:   tdpl=ftdplxg(tg,pv)
1084!
1085!   Input argument list:
1086!     tg         Real(krealfp) guess dewpoint temperature in Kelvin
1087!     pv         Real(krealfp) vapor pressure in Pascals
1088!
1089!   Output argument list:
1090!     ftdplxg    Real(krealfp) dewpoint temperature in Kelvin
1091!
1092! Attributes:
1093!   Language: Fortran 90.
1094!
1095!$$$
1096    implicit none
1097    real(krealfp) ftdplxg
1098    real(krealfp),intent(in):: tg,pv
1099    real(krealfp),parameter:: terrm=1.e-6
1100    real(krealfp),parameter:: dldt=con_cvap-con_cliq
1101    real(krealfp),parameter:: heat=con_hvap
1102    real(krealfp),parameter:: xpona=-dldt/con_rv
1103    real(krealfp),parameter:: xponb=-dldt/con_rv+heat/(con_rv*con_ttp)
1104    real(krealfp) t,tr,pvt,el,dpvt,terr
1105    integer i
1106! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1107    t=tg
1108    do i=1,100
1109      tr=con_ttp/t
1110      pvt=con_psat*(tr**xpona)*exp(xponb*(1.-tr))
1111      el=heat+dldt*(t-con_ttp)
1112      dpvt=el*pvt/(con_rv*t**2)
1113      terr=(pvt-pv)/dpvt
1114      t=t-terr
1115      if(abs(terr).le.terrm) exit
1116    enddo
1117    ftdplxg=t
1118! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1119  end function
1120!-------------------------------------------------------------------------------
1121  subroutine gtdpi
1122!$$$     Subprogram Documentation Block
1123!
1124! Subprogram: gtdpi        Compute dewpoint temperature over ice table
1125!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1126!
1127! Abstract: Compute dewpoint temperature table as a function of
1128!   vapor pressure for inlinable function ftdpi.
1129!   Exact dewpoint temperatures are calculated in subprogram ftdpixg.
1130!   The current implementation computes a table with a length
1131!   of 5001 for vapor pressures ranging from 0.1 to 1000.1 Pascals
1132!   giving a dewpoint temperature range of 197 to 279 Kelvin.
1133!
1134! Program History Log:
1135!   91-05-07  Iredell
1136!   94-12-30  Iredell             expand table
1137! 1999-03-01  Iredell             f90 module
1138! 2001-02-26  Iredell             ice phase
1139!
1140! Usage:  call gtdpi
1141!
1142! Subprograms called:
1143!   (ftdpixg)  inlinable function to compute dewpoint temperature over ice
1144!
1145! Attributes:
1146!   Language: Fortran 90.
1147!
1148!$$$
1149    implicit none
1150    integer jx
1151    real(krealfp) xmin,xmax,xinc,t,x,pv
1152! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1153    xmin=0.1
1154    xmax=1000.1
1155    xinc=(xmax-xmin)/(nxtdpi-1)
1156    c1xtdpi=1.-xmin/xinc
1157    c2xtdpi=1./xinc
1158    t=197.0
1159    do jx=1,nxtdpi
1160      x=xmin+(jx-1)*xinc
1161      pv=x
1162      t=ftdpixg(t,pv)
1163      tbtdpi(jx)=t
1164    enddo
1165! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1166  end subroutine
1167!-------------------------------------------------------------------------------
1168! elemental function ftdpi(pv)
1169  function ftdpi(pv)
1170!$$$     Subprogram Documentation Block
1171!
1172! Subprogram: ftdpi        Compute dewpoint temperature over ice
1173!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1174!
1175! Abstract: Compute dewpoint temperature from vapor pressure.
1176!   A linear interpolation is done between values in a lookup table
1177!   computed in gtdpi. See documentation for ftdpixg for details.
1178!   Input values outside table range are reset to table extrema.
1179!   The interpolation accuracy is better than 0.0005 Kelvin
1180!   for dewpoint temperatures greater than 250 Kelvin,
1181!   but decreases to 0.02 Kelvin for a dewpoint around 230 Kelvin.
1182!   On the Cray, ftdpi is about 75 times faster than exact calculation.
1183!   This function should be expanded inline in the calling routine.
1184!
1185! Program History Log:
1186!   91-05-07  Iredell             made into inlinable function
1187!   94-12-30  Iredell             expand table
1188! 1999-03-01  Iredell             f90 module
1189! 2001-02-26  Iredell             ice phase
1190!
1191! Usage:   tdpi=ftdpi(pv)
1192!
1193!   Input argument list:
1194!     pv         Real(krealfp) vapor pressure in Pascals
1195!
1196!   Output argument list:
1197!     ftdpi      Real(krealfp) dewpoint temperature in Kelvin
1198!
1199! Attributes:
1200!   Language: Fortran 90.
1201!
1202!$$$
1203    implicit none
1204    real(krealfp) ftdpi
1205    real(krealfp),intent(in):: pv
1206    integer jx
1207    real(krealfp) xj
1208! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1209    xj=min(max(c1xtdpi+c2xtdpi*pv,1._krealfp),real(nxtdpi,krealfp))
1210    jx=min(xj,nxtdpi-1._krealfp)
1211    ftdpi=tbtdpi(jx)+(xj-jx)*(tbtdpi(jx+1)-tbtdpi(jx))
1212! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1213  end function
1214!-------------------------------------------------------------------------------
1215! elemental function ftdpiq(pv)
1216  function ftdpiq(pv)
1217!$$$     Subprogram Documentation Block
1218!
1219! Subprogram: ftdpiq       Compute dewpoint temperature over ice
1220!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1221!
1222! Abstract: Compute dewpoint temperature from vapor pressure.
1223!   A quadratic interpolation is done between values in a lookup table
1224!   computed in gtdpi. see documentation for ftdpixg for details.
1225!   Input values outside table range are reset to table extrema.
1226!   the interpolation accuracy is better than 0.00001 Kelvin
1227!   for dewpoint temperatures greater than 250 Kelvin,
1228!   but decreases to 0.002 Kelvin for a dewpoint around 230 Kelvin.
1229!   On the Cray, ftdpiq is about 60 times faster than exact calculation.
1230!   This function should be expanded inline in the calling routine.
1231!
1232! Program History Log:
1233!   91-05-07  Iredell             made into inlinable function
1234!   94-12-30  Iredell             quadratic interpolation
1235! 1999-03-01  Iredell             f90 module
1236! 2001-02-26  Iredell             ice phase
1237!
1238! Usage:   tdpi=ftdpiq(pv)
1239!
1240!   Input argument list:
1241!     pv         Real(krealfp) vapor pressure in Pascals
1242!
1243!   Output argument list:
1244!     ftdpiq     Real(krealfp) dewpoint temperature in Kelvin
1245!
1246! Attributes:
1247!   Language: Fortran 90.
1248!
1249!$$$
1250    implicit none
1251    real(krealfp) ftdpiq
1252    real(krealfp),intent(in):: pv
1253    integer jx
1254    real(krealfp) xj,dxj,fj1,fj2,fj3
1255! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1256    xj=min(max(c1xtdpi+c2xtdpi*pv,1._krealfp),real(nxtdpi,krealfp))
1257    jx=min(max(nint(xj),2),nxtdpi-1)
1258    dxj=xj-jx
1259    fj1=tbtdpi(jx-1)
1260    fj2=tbtdpi(jx)
1261    fj3=tbtdpi(jx+1)
1262    ftdpiq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
1263! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1264  end function
1265!-------------------------------------------------------------------------------
1266! elemental function ftdpix(pv)
1267  function ftdpix(pv)
1268!$$$     Subprogram Documentation Block
1269!
1270! Subprogram: ftdpix       Compute dewpoint temperature over ice
1271!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1272!
1273! Abstract: exactly compute dewpoint temperature from vapor pressure.
1274!   An approximate dewpoint temperature for function ftdpixg
1275!   is obtained using ftdpi so gtdpi must be already called.
1276!   See documentation for ftdpixg for details.
1277!
1278! Program History Log:
1279!   91-05-07  Iredell             made into inlinable function
1280!   94-12-30  Iredell             exact computation
1281! 1999-03-01  Iredell             f90 module
1282! 2001-02-26  Iredell             ice phase
1283!
1284! Usage:   tdpi=ftdpix(pv)
1285!
1286!   Input argument list:
1287!     pv         Real(krealfp) vapor pressure in Pascals
1288!
1289!   Output argument list:
1290!     ftdpix     Real(krealfp) dewpoint temperature in Kelvin
1291!
1292! Subprograms called:
1293!   (ftdpi)    inlinable function to compute dewpoint temperature over ice
1294!   (ftdpixg)  inlinable function to compute dewpoint temperature over ice
1295!
1296! Attributes:
1297!   Language: Fortran 90.
1298!
1299!$$$
1300    implicit none
1301    real(krealfp) ftdpix
1302    real(krealfp),intent(in):: pv
1303    real(krealfp) tg
1304! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1305    tg=ftdpi(pv)
1306    ftdpix=ftdpixg(tg,pv)
1307! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1308  end function
1309!-------------------------------------------------------------------------------
1310! elemental function ftdpixg(tg,pv)
1311  function ftdpixg(tg,pv)
1312!$$$     Subprogram Documentation Block
1313!
1314! Subprogram: ftdpixg      Compute dewpoint temperature over ice
1315!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1316!
1317! Abstract: Exactly compute dewpoint temperature from vapor pressure.
1318!   A guess dewpoint temperature must be provided.
1319!   The water model assumes a perfect gas, constant specific heats
1320!   for gas and ice, and neglects the volume of the ice.
1321!   The model does account for the variation of the latent heat
1322!   of sublimation with temperature.  The liquid option is not included.
1323!   The Clausius-Clapeyron equation is integrated from the triple point
1324!   to get the formula
1325!       pvs=con_psat*(tr**xa)*exp(xb*(1.-tr))
1326!   where tr is ttp/t and other values are physical constants.
1327!   The formula is inverted by iterating Newtonian approximations
1328!   for each pvs until t is found to within 1.e-6 Kelvin.
1329!   This function can be expanded inline in the calling routine.
1330!
1331! Program History Log:
1332!   91-05-07  Iredell             made into inlinable function
1333!   94-12-30  Iredell             exact computation
1334! 1999-03-01  Iredell             f90 module
1335! 2001-02-26  Iredell             ice phase
1336!
1337! Usage:   tdpi=ftdpixg(tg,pv)
1338!
1339!   Input argument list:
1340!     tg         Real(krealfp) guess dewpoint temperature in Kelvin
1341!     pv         Real(krealfp) vapor pressure in Pascals
1342!
1343!   Output argument list:
1344!     ftdpixg    Real(krealfp) dewpoint temperature in Kelvin
1345!
1346! Attributes:
1347!   Language: Fortran 90.
1348!
1349!$$$
1350    implicit none
1351    real(krealfp) ftdpixg
1352    real(krealfp),intent(in):: tg,pv
1353    real(krealfp),parameter:: terrm=1.e-6
1354    real(krealfp),parameter:: dldt=con_cvap-con_csol
1355    real(krealfp),parameter:: heat=con_hvap+con_hfus
1356    real(krealfp),parameter:: xpona=-dldt/con_rv
1357    real(krealfp),parameter:: xponb=-dldt/con_rv+heat/(con_rv*con_ttp)
1358    real(krealfp) t,tr,pvt,el,dpvt,terr
1359    integer i
1360! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1361    t=tg
1362    do i=1,100
1363      tr=con_ttp/t
1364      pvt=con_psat*(tr**xpona)*exp(xponb*(1.-tr))
1365      el=heat+dldt*(t-con_ttp)
1366      dpvt=el*pvt/(con_rv*t**2)
1367      terr=(pvt-pv)/dpvt
1368      t=t-terr
1369      if(abs(terr).le.terrm) exit
1370    enddo
1371    ftdpixg=t
1372! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1373  end function
1374!-------------------------------------------------------------------------------
1375  subroutine gtdp
1376!$$$     Subprogram Documentation Block
1377!
1378! Subprogram: gtdp         Compute dewpoint temperature table
1379!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1380!
1381! Abstract: Compute dewpoint temperature table as a function of
1382!   vapor pressure for inlinable function ftdp.
1383!   Exact dewpoint temperatures are calculated in subprogram ftdpxg.
1384!   The current implementation computes a table with a length
1385!   of 5001 for vapor pressures ranging from 0.5 to 1000.5 Pascals
1386!   giving a dewpoint temperature range of 208 to 319 Kelvin.
1387!
1388! Program History Log:
1389!   91-05-07  Iredell
1390!   94-12-30  Iredell             expand table
1391! 1999-03-01  Iredell             f90 module
1392! 2001-02-26  Iredell             ice phase
1393!
1394! Usage:  call gtdp
1395!
1396! Subprograms called:
1397!   (ftdpxg)   inlinable function to compute dewpoint temperature
1398!
1399! Attributes:
1400!   Language: Fortran 90.
1401!
1402!$$$
1403    implicit none
1404    integer jx
1405    real(krealfp) xmin,xmax,xinc,t,x,pv
1406! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1407    xmin=0.5
1408    xmax=10000.5
1409    xinc=(xmax-xmin)/(nxtdp-1)
1410    c1xtdp=1.-xmin/xinc
1411    c2xtdp=1./xinc
1412    t=208.0
1413    do jx=1,nxtdp
1414      x=xmin+(jx-1)*xinc
1415      pv=x
1416      t=ftdpxg(t,pv)
1417      tbtdp(jx)=t
1418    enddo
1419! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1420  end subroutine
1421!-------------------------------------------------------------------------------
1422! elemental function ftdp(pv)
1423  function ftdp(pv)
1424!$$$     Subprogram Documentation Block
1425!
1426! Subprogram: ftdp         Compute dewpoint temperature
1427!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1428!
1429! Abstract: Compute dewpoint temperature from vapor pressure.
1430!   A linear interpolation is done between values in a lookup table
1431!   computed in gtdp. See documentation for ftdpxg for details.
1432!   Input values outside table range are reset to table extrema.
1433!   The interpolation accuracy is better than 0.0005 Kelvin
1434!   for dewpoint temperatures greater than 250 Kelvin,
1435!   but decreases to 0.02 Kelvin for a dewpoint around 230 Kelvin.
1436!   On the Cray, ftdp is about 75 times faster than exact calculation.
1437!   This function should be expanded inline in the calling routine.
1438!
1439! Program History Log:
1440!   91-05-07  Iredell             made into inlinable function
1441!   94-12-30  Iredell             expand table
1442! 1999-03-01  Iredell             f90 module
1443! 2001-02-26  Iredell             ice phase
1444!
1445! Usage:   tdp=ftdp(pv)
1446!
1447!   Input argument list:
1448!     pv         Real(krealfp) vapor pressure in Pascals
1449!
1450!   Output argument list:
1451!     ftdp       Real(krealfp) dewpoint temperature in Kelvin
1452!
1453! Attributes:
1454!   Language: Fortran 90.
1455!
1456!$$$
1457    implicit none
1458    real(krealfp) ftdp
1459    real(krealfp),intent(in):: pv
1460    integer jx
1461    real(krealfp) xj
1462! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1463    xj=min(max(c1xtdp+c2xtdp*pv,1._krealfp),real(nxtdp,krealfp))
1464    jx=min(xj,nxtdp-1._krealfp)
1465    ftdp=tbtdp(jx)+(xj-jx)*(tbtdp(jx+1)-tbtdp(jx))
1466! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1467  end function
1468!-------------------------------------------------------------------------------
1469! elemental function ftdpq(pv)
1470  function ftdpq(pv)
1471!$$$     Subprogram Documentation Block
1472!
1473! Subprogram: ftdpq        Compute dewpoint temperature
1474!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1475!
1476! Abstract: Compute dewpoint temperature from vapor pressure.
1477!   A quadratic interpolation is done between values in a lookup table
1478!   computed in gtdp. see documentation for ftdpxg for details.
1479!   Input values outside table range are reset to table extrema.
1480!   the interpolation accuracy is better than 0.00001 Kelvin
1481!   for dewpoint temperatures greater than 250 Kelvin,
1482!   but decreases to 0.002 Kelvin for a dewpoint around 230 Kelvin.
1483!   On the Cray, ftdpq is about 60 times faster than exact calculation.
1484!   This function should be expanded inline in the calling routine.
1485!
1486! Program History Log:
1487!   91-05-07  Iredell             made into inlinable function
1488!   94-12-30  Iredell             quadratic interpolation
1489! 1999-03-01  Iredell             f90 module
1490! 2001-02-26  Iredell             ice phase
1491!
1492! Usage:   tdp=ftdpq(pv)
1493!
1494!   Input argument list:
1495!     pv         Real(krealfp) vapor pressure in Pascals
1496!
1497!   Output argument list:
1498!     ftdpq      Real(krealfp) dewpoint temperature in Kelvin
1499!
1500! Attributes:
1501!   Language: Fortran 90.
1502!
1503!$$$
1504    implicit none
1505    real(krealfp) ftdpq
1506    real(krealfp),intent(in):: pv
1507    integer jx
1508    real(krealfp) xj,dxj,fj1,fj2,fj3
1509! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1510    xj=min(max(c1xtdp+c2xtdp*pv,1._krealfp),real(nxtdp,krealfp))
1511    jx=min(max(nint(xj),2),nxtdp-1)
1512    dxj=xj-jx
1513    fj1=tbtdp(jx-1)
1514    fj2=tbtdp(jx)
1515    fj3=tbtdp(jx+1)
1516    ftdpq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
1517! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1518  end function
1519!-------------------------------------------------------------------------------
1520! elemental function ftdpx(pv)
1521  function ftdpx(pv)
1522!$$$     Subprogram Documentation Block
1523!
1524! Subprogram: ftdpx        Compute dewpoint temperature
1525!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1526!
1527! Abstract: exactly compute dewpoint temperature from vapor pressure.
1528!   An approximate dewpoint temperature for function ftdpxg
1529!   is obtained using ftdp so gtdp must be already called.
1530!   See documentation for ftdpxg for details.
1531!
1532! Program History Log:
1533!   91-05-07  Iredell             made into inlinable function
1534!   94-12-30  Iredell             exact computation
1535! 1999-03-01  Iredell             f90 module
1536! 2001-02-26  Iredell             ice phase
1537!
1538! Usage:   tdp=ftdpx(pv)
1539!
1540!   Input argument list:
1541!     pv         Real(krealfp) vapor pressure in Pascals
1542!
1543!   Output argument list:
1544!     ftdpx      Real(krealfp) dewpoint temperature in Kelvin
1545!
1546! Subprograms called:
1547!   (ftdp)     inlinable function to compute dewpoint temperature
1548!   (ftdpxg)   inlinable function to compute dewpoint temperature
1549!
1550! Attributes:
1551!   Language: Fortran 90.
1552!
1553!$$$
1554    implicit none
1555    real(krealfp) ftdpx
1556    real(krealfp),intent(in):: pv
1557    real(krealfp) tg
1558! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1559    tg=ftdp(pv)
1560    ftdpx=ftdpxg(tg,pv)
1561! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1562  end function
1563!-------------------------------------------------------------------------------
1564! elemental function ftdpxg(tg,pv)
1565  function ftdpxg(tg,pv)
1566!$$$     Subprogram Documentation Block
1567!
1568! Subprogram: ftdpxg       Compute dewpoint temperature
1569!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1570!
1571! Abstract: Exactly compute dewpoint temperature from vapor pressure.
1572!   A guess dewpoint temperature must be provided.
1573!   The saturation vapor pressure over either liquid and ice is computed
1574!   over liquid for temperatures above the triple point,
1575!   over ice for temperatures 20 degress below the triple point,
1576!   and a linear combination of the two for temperatures in between.
1577!   The water model assumes a perfect gas, constant specific heats
1578!   for gas, liquid and ice, and neglects the volume of the condensate.
1579!   The model does account for the variation of the latent heat
1580!   of condensation and sublimation with temperature.
1581!   The Clausius-Clapeyron equation is integrated from the triple point
1582!   to get the formula
1583!       pvsl=con_psat*(tr**xa)*exp(xb*(1.-tr))
1584!   where tr is ttp/t and other values are physical constants.
1585!   The reference for this decision is Emanuel(1994), pages 116-117.
1586!   The formula is inverted by iterating Newtonian approximations
1587!   for each pvs until t is found to within 1.e-6 Kelvin.
1588!   This function can be expanded inline in the calling routine.
1589!
1590! Program History Log:
1591!   91-05-07  Iredell             made into inlinable function
1592!   94-12-30  Iredell             exact computation
1593! 1999-03-01  Iredell             f90 module
1594! 2001-02-26  Iredell             ice phase
1595!
1596! Usage:   tdp=ftdpxg(tg,pv)
1597!
1598!   Input argument list:
1599!     tg         Real(krealfp) guess dewpoint temperature in Kelvin
1600!     pv         Real(krealfp) vapor pressure in Pascals
1601!
1602!   Output argument list:
1603!     ftdpxg     Real(krealfp) dewpoint temperature in Kelvin
1604!
1605! Attributes:
1606!   Language: Fortran 90.
1607!
1608!$$$
1609    implicit none
1610    real(krealfp) ftdpxg
1611    real(krealfp),intent(in):: tg,pv
1612    real(krealfp),parameter:: terrm=1.e-6
1613    real(krealfp),parameter:: tliq=con_ttp
1614    real(krealfp),parameter:: tice=con_ttp-20.0
1615    real(krealfp),parameter:: dldtl=con_cvap-con_cliq
1616    real(krealfp),parameter:: heatl=con_hvap
1617    real(krealfp),parameter:: xponal=-dldtl/con_rv
1618    real(krealfp),parameter:: xponbl=-dldtl/con_rv+heatl/(con_rv*con_ttp)
1619    real(krealfp),parameter:: dldti=con_cvap-con_csol
1620    real(krealfp),parameter:: heati=con_hvap+con_hfus
1621    real(krealfp),parameter:: xponai=-dldti/con_rv
1622    real(krealfp),parameter:: xponbi=-dldti/con_rv+heati/(con_rv*con_ttp)
1623    real(krealfp) t,tr,w,pvtl,pvti,pvt,ell,eli,el,dpvt,terr
1624    integer i
1625! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1626    t=tg
1627    do i=1,100
1628      tr=con_ttp/t
1629      if(t.ge.tliq) then
1630        pvt=con_psat*(tr**xponal)*exp(xponbl*(1.-tr))
1631        el=heatl+dldtl*(t-con_ttp)
1632        dpvt=el*pvt/(con_rv*t**2)
1633      elseif(t.lt.tice) then
1634        pvt=con_psat*(tr**xponai)*exp(xponbi*(1.-tr))
1635        el=heati+dldti*(t-con_ttp)
1636        dpvt=el*pvt/(con_rv*t**2)
1637      else
1638        w=(t-tice)/(tliq-tice)
1639        pvtl=con_psat*(tr**xponal)*exp(xponbl*(1.-tr))
1640        pvti=con_psat*(tr**xponai)*exp(xponbi*(1.-tr))
1641        pvt=w*pvtl+(1.-w)*pvti
1642        ell=heatl+dldtl*(t-con_ttp)
1643        eli=heati+dldti*(t-con_ttp)
1644        dpvt=(w*ell*pvtl+(1.-w)*eli*pvti)/(con_rv*t**2)
1645      endif
1646      terr=(pvt-pv)/dpvt
1647      t=t-terr
1648      if(abs(terr).le.terrm) exit
1649    enddo
1650    ftdpxg=t
1651! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1652  end function
1653!-------------------------------------------------------------------------------
1654  subroutine gthe
1655!$$$     Subprogram Documentation Block
1656!
1657! Subprogram: gthe        Compute equivalent potential temperature table
1658!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1659!
1660! Abstract: Compute equivalent potential temperature table
1661!   as a function of LCL temperature and pressure over 1e5 Pa
1662!   to the kappa power for function fthe.
1663!   Equivalent potential temperatures are calculated in subprogram fthex
1664!   the current implementation computes a table with a first dimension
1665!   of 241 for temperatures ranging from 183.16 to 303.16 Kelvin
1666!   and a second dimension of 151 for pressure over 1e5 Pa
1667!   to the kappa power ranging from 0.04**rocp to 1.10**rocp.
1668!
1669! Program History Log:
1670!   91-05-07  Iredell
1671!   94-12-30  Iredell             expand table
1672! 1999-03-01  Iredell             f90 module
1673!
1674! Usage:  call gthe
1675!
1676! Subprograms called:
1677!   (fthex)    inlinable function to compute equiv. pot. temperature
1678!
1679! Attributes:
1680!   Language: Fortran 90.
1681!
1682!$$$
1683    implicit none
1684    integer jx,jy
1685    real(krealfp) xmin,xmax,ymin,ymax,xinc,yinc,x,y,pk,t
1686! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1687    xmin=con_ttp-90._krealfp
1688    xmax=con_ttp+30._krealfp
1689    ymin=0.04_krealfp**con_rocp
1690    ymax=1.10_krealfp**con_rocp
1691    xinc=(xmax-xmin)/(nxthe-1)
1692    c1xthe=1.-xmin/xinc
1693    c2xthe=1./xinc
1694    yinc=(ymax-ymin)/(nythe-1)
1695    c1ythe=1.-ymin/yinc
1696    c2ythe=1./yinc
1697    do jy=1,nythe
1698      y=ymin+(jy-1)*yinc
1699      pk=y
1700      do jx=1,nxthe
1701        x=xmin+(jx-1)*xinc
1702        t=x
1703        tbthe(jx,jy)=fthex(t,pk)
1704      enddo
1705    enddo
1706! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1707  end subroutine
1708!-------------------------------------------------------------------------------
1709! elemental function fthe(t,pk)
1710  function fthe(t,pk)
1711!$$$     Subprogram Documentation Block
1712!
1713! Subprogram: fthe         Compute equivalent potential temperature
1714!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1715!
1716! Abstract: Compute equivalent potential temperature at the LCL
1717!   from temperature and pressure over 1e5 Pa to the kappa power.
1718!   A bilinear interpolation is done between values in a lookup table
1719!   computed in gthe. see documentation for fthex for details.
1720!   Input values outside table range are reset to table extrema,
1721!   except zero is returned for too cold or high LCLs.
1722!   The interpolation accuracy is better than 0.01 Kelvin.
1723!   On the Cray, fthe is almost 6 times faster than exact calculation.
1724!   This function should be expanded inline in the calling routine.
1725!
1726! Program History Log:
1727!   91-05-07  Iredell             made into inlinable function
1728!   94-12-30  Iredell             expand table
1729! 1999-03-01  Iredell             f90 module
1730!
1731! Usage:   the=fthe(t,pk)
1732!
1733!   Input argument list:
1734!     t          Real(krealfp) LCL temperature in Kelvin
1735!     pk         Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
1736!
1737!   Output argument list:
1738!     fthe       Real(krealfp) equivalent potential temperature in Kelvin
1739!
1740! Attributes:
1741!   Language: Fortran 90.
1742!
1743!$$$
1744    implicit none
1745    real(krealfp) fthe
1746    real(krealfp),intent(in):: t,pk
1747    integer jx,jy
1748    real(krealfp) xj,yj,ftx1,ftx2
1749! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1750    xj=min(c1xthe+c2xthe*t,real(nxthe,krealfp))
1751    yj=min(c1ythe+c2ythe*pk,real(nythe,krealfp))
1752    if(xj.ge.1..and.yj.ge.1.) then
1753      jx=min(xj,nxthe-1._krealfp)
1754      jy=min(yj,nythe-1._krealfp)
1755      ftx1=tbthe(jx,jy)+(xj-jx)*(tbthe(jx+1,jy)-tbthe(jx,jy))
1756      ftx2=tbthe(jx,jy+1)+(xj-jx)*(tbthe(jx+1,jy+1)-tbthe(jx,jy+1))
1757      fthe=ftx1+(yj-jy)*(ftx2-ftx1)
1758    else
1759      fthe=0.
1760    endif
1761! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1762  end function
1763!-------------------------------------------------------------------------------
1764! elemental function ftheq(t,pk)
1765  function ftheq(t,pk)
1766!$$$     Subprogram Documentation Block
1767!
1768! Subprogram: ftheq        Compute equivalent potential temperature
1769!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1770!
1771! Abstract: Compute equivalent potential temperature at the LCL
1772!   from temperature and pressure over 1e5 Pa to the kappa power.
1773!   A biquadratic interpolation is done between values in a lookup table
1774!   computed in gthe. see documentation for fthex for details.
1775!   Input values outside table range are reset to table extrema,
1776!   except zero is returned for too cold or high LCLs.
1777!   The interpolation accuracy is better than 0.0002 Kelvin.
1778!   On the Cray, ftheq is almost 3 times faster than exact calculation.
1779!   This function should be expanded inline in the calling routine.
1780!
1781! Program History Log:
1782!   91-05-07  Iredell             made into inlinable function
1783!   94-12-30  Iredell             quadratic interpolation
1784! 1999-03-01  Iredell             f90 module
1785!
1786! Usage:   the=ftheq(t,pk)
1787!
1788!   Input argument list:
1789!     t          Real(krealfp) LCL temperature in Kelvin
1790!     pk         Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
1791!
1792!   Output argument list:
1793!     ftheq      Real(krealfp) equivalent potential temperature in Kelvin
1794!
1795! Attributes:
1796!   Language: Fortran 90.
1797!
1798!$$$
1799    implicit none
1800    real(krealfp) ftheq
1801    real(krealfp),intent(in):: t,pk
1802    integer jx,jy
1803    real(krealfp) xj,yj,dxj,dyj
1804    real(krealfp) ft11,ft12,ft13,ft21,ft22,ft23,ft31,ft32,ft33
1805    real(krealfp) ftx1,ftx2,ftx3
1806! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1807    xj=min(c1xthe+c2xthe*t,real(nxthe,krealfp))
1808    yj=min(c1ythe+c2ythe*pk,real(nythe,krealfp))
1809    if(xj.ge.1..and.yj.ge.1.) then
1810      jx=min(max(nint(xj),2),nxthe-1)
1811      jy=min(max(nint(yj),2),nythe-1)
1812      dxj=xj-jx
1813      dyj=yj-jy
1814      ft11=tbthe(jx-1,jy-1)
1815      ft12=tbthe(jx-1,jy)
1816      ft13=tbthe(jx-1,jy+1)
1817      ft21=tbthe(jx,jy-1)
1818      ft22=tbthe(jx,jy)
1819      ft23=tbthe(jx,jy+1)
1820      ft31=tbthe(jx+1,jy-1)
1821      ft32=tbthe(jx+1,jy)
1822      ft33=tbthe(jx+1,jy+1)
1823      ftx1=(((ft31+ft11)/2-ft21)*dxj+(ft31-ft11)/2)*dxj+ft21
1824      ftx2=(((ft32+ft12)/2-ft22)*dxj+(ft32-ft12)/2)*dxj+ft22
1825      ftx3=(((ft33+ft13)/2-ft23)*dxj+(ft33-ft13)/2)*dxj+ft23
1826      ftheq=(((ftx3+ftx1)/2-ftx2)*dyj+(ftx3-ftx1)/2)*dyj+ftx2
1827    else
1828      ftheq=0.
1829    endif
1830! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1831  end function
1832!-------------------------------------------------------------------------------
1833! elemental function fthex(t,pk)
1834            function fthex(t,pk)
1835!$$$     Subprogram Documentation Block
1836!
1837! Subprogram: fthex        Compute equivalent potential temperature
1838!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1839!
1840! Abstract: Exactly compute equivalent potential temperature at the LCL
1841!   from temperature and pressure over 1e5 Pa to the kappa power.
1842!   Equivalent potential temperature is constant for a saturated parcel
1843!   rising adiabatically up a moist adiabat when the heat and mass
1844!   of the condensed water are neglected.  Ice is also neglected.
1845!   The formula for equivalent potential temperature (Holton) is
1846!       the=t*(pd**(-rocp))*exp(el*eps*pv/(cp*t*pd))
1847!   where t is the temperature, pv is the saturated vapor pressure,
1848!   pd is the dry pressure p-pv, el is the temperature dependent
1849!   latent heat of condensation hvap+dldt*(t-ttp), and other values
1850!   are physical constants defined in parameter statements in the code.
1851!   Zero is returned if the input values make saturation impossible.
1852!   This function should be expanded inline in the calling routine.
1853!
1854! Program History Log:
1855!   91-05-07  Iredell             made into inlinable function
1856!   94-12-30  Iredell             exact computation
1857! 1999-03-01  Iredell             f90 module
1858!
1859! Usage:   the=fthex(t,pk)
1860!
1861!   Input argument list:
1862!     t          Real(krealfp) LCL temperature in Kelvin
1863!     pk         Real(krealfp) LCL pressure over 1e5 Pa to the kappa power
1864!
1865!   Output argument list:
1866!     fthex      Real(krealfp) equivalent potential temperature in Kelvin
1867!
1868! Attributes:
1869!   Language: Fortran 90.
1870!
1871!$$$
1872    implicit none
1873    real(krealfp) fthex
1874    real(krealfp),intent(in):: t,pk
1875    real(krealfp) p,tr,pv,pd,el,expo,expmax
1876! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1877    p=pk**con_cpor
1878    tr=con_ttp/t
1879    pv=psatb*(tr**con_xpona)*exp(con_xponb*(1.-tr))
1880    pd=p-pv
1881    if(pd.gt.pv) then
1882      el=con_hvap+con_dldt*(t-con_ttp)
1883      expo=el*con_eps*pv/(con_cp*t*pd)
1884      fthex=t*pd**(-con_rocp)*exp(expo)
1885    else
1886      fthex=0.
1887    endif
1888! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1889  end function
1890!-------------------------------------------------------------------------------
1891  subroutine gtma
1892!$$$     Subprogram Documentation Block
1893!
1894! Subprogram: gtma         Compute moist adiabat tables
1895!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1896!
1897! Abstract: Compute temperature and specific humidity tables
1898!   as a function of equivalent potential temperature and
1899!   pressure over 1e5 Pa to the kappa power for subprogram stma.
1900!   Exact parcel temperatures are calculated in subprogram stmaxg.
1901!   The current implementation computes a table with a first dimension
1902!   of 151 for equivalent potential temperatures ranging from 200 to 500
1903!   Kelvin and a second dimension of 121 for pressure over 1e5 Pa
1904!   to the kappa power ranging from 0.01**rocp to 1.10**rocp.
1905!
1906! Program History Log:
1907!   91-05-07  Iredell
1908!   94-12-30  Iredell             expand table
1909! 1999-03-01  Iredell             f90 module
1910!
1911! Usage:  call gtma
1912!
1913! Subprograms called:
1914!   (stmaxg)   inlinable subprogram to compute parcel temperature
1915!
1916! Attributes:
1917!   Language: Fortran 90.
1918!
1919!$$$
1920    implicit none
1921    integer jx,jy
1922    real(krealfp) xmin,xmax,ymin,ymax,xinc,yinc,x,y,pk,the,t,q,tg
1923! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1924    xmin=200._krealfp
1925    xmax=500._krealfp
1926    ymin=0.01_krealfp**con_rocp
1927    ymax=1.10_krealfp**con_rocp
1928    xinc=(xmax-xmin)/(nxma-1)
1929    c1xma=1.-xmin/xinc
1930    c2xma=1./xinc
1931    yinc=(ymax-ymin)/(nyma-1)
1932    c1yma=1.-ymin/yinc
1933    c2yma=1./yinc
1934    do jy=1,nyma
1935      y=ymin+(jy-1)*yinc
1936      pk=y
1937      tg=xmin*y
1938      do jx=1,nxma
1939        x=xmin+(jx-1)*xinc
1940        the=x
1941        call stmaxg(tg,the,pk,t,q)
1942        tbtma(jx,jy)=t
1943        tbqma(jx,jy)=q
1944        tg=t
1945      enddo
1946    enddo
1947! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1948  end subroutine
1949!-------------------------------------------------------------------------------
1950! elemental subroutine stma(the,pk,tma,qma)
1951  subroutine stma(the,pk,tma,qma)
1952!$$$     Subprogram Documentation Block
1953!
1954! Subprogram: stma         Compute moist adiabat temperature
1955!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
1956!
1957! Abstract: Compute temperature and specific humidity of a parcel
1958!   lifted up a moist adiabat from equivalent potential temperature
1959!   at the LCL and pressure over 1e5 Pa to the kappa power.
1960!   Bilinear interpolations are done between values in a lookup table
1961!   computed in gtma. See documentation for stmaxg for details.
1962!   Input values outside table range are reset to table extrema.
1963!   The interpolation accuracy is better than 0.01 Kelvin
1964!   and 5.e-6 kg/kg for temperature and humidity, respectively.
1965!   On the Cray, stma is about 35 times faster than exact calculation.
1966!   This subprogram should be expanded inline in the calling routine.
1967!
1968! Program History Log:
1969!   91-05-07  Iredell             made into inlinable function
1970!   94-12-30  Iredell             expand table
1971! 1999-03-01  Iredell             f90 module
1972!
1973! Usage:  call stma(the,pk,tma,qma)
1974!
1975!   Input argument list:
1976!     the        Real(krealfp) equivalent potential temperature in Kelvin
1977!     pk         Real(krealfp) pressure over 1e5 Pa to the kappa power
1978!
1979!   Output argument list:
1980!     tma        Real(krealfp) parcel temperature in Kelvin
1981!     qma        Real(krealfp) parcel specific humidity in kg/kg
1982!
1983! Attributes:
1984!   Language: Fortran 90.
1985!
1986!$$$
1987    implicit none
1988    real(krealfp),intent(in):: the,pk
1989    real(krealfp),intent(out):: tma,qma
1990    integer jx,jy
1991    real(krealfp) xj,yj,ftx1,ftx2,qx1,qx2
1992! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1993    xj=min(max(c1xma+c2xma*the,1._krealfp),real(nxma,krealfp))
1994    yj=min(max(c1yma+c2yma*pk,1._krealfp),real(nyma,krealfp))
1995    jx=min(xj,nxma-1._krealfp)
1996    jy=min(yj,nyma-1._krealfp)
1997    ftx1=tbtma(jx,jy)+(xj-jx)*(tbtma(jx+1,jy)-tbtma(jx,jy))
1998    ftx2=tbtma(jx,jy+1)+(xj-jx)*(tbtma(jx+1,jy+1)-tbtma(jx,jy+1))
1999    tma=ftx1+(yj-jy)*(ftx2-ftx1)
2000    qx1=tbqma(jx,jy)+(xj-jx)*(tbqma(jx+1,jy)-tbqma(jx,jy))
2001    qx2=tbqma(jx,jy+1)+(xj-jx)*(tbqma(jx+1,jy+1)-tbqma(jx,jy+1))
2002    qma=qx1+(yj-jy)*(qx2-qx1)
2003! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2004  end subroutine
2005!-------------------------------------------------------------------------------
2006! elemental subroutine stmaq(the,pk,tma,qma)
2007  subroutine stmaq(the,pk,tma,qma)
2008!$$$     Subprogram Documentation Block
2009!
2010! Subprogram: stmaq        Compute moist adiabat temperature
2011!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2012!
2013! Abstract: Compute temperature and specific humidity of a parcel
2014!   lifted up a moist adiabat from equivalent potential temperature
2015!   at the LCL and pressure over 1e5 Pa to the kappa power.
2016!   Biquadratic interpolations are done between values in a lookup table
2017!   computed in gtma. See documentation for stmaxg for details.
2018!   Input values outside table range are reset to table extrema.
2019!   the interpolation accuracy is better than 0.0005 Kelvin
2020!   and 1.e-7 kg/kg for temperature and humidity, respectively.
2021!   On the Cray, stmaq is about 25 times faster than exact calculation.
2022!   This subprogram should be expanded inline in the calling routine.
2023!
2024! Program History Log:
2025!   91-05-07  Iredell             made into inlinable function
2026!   94-12-30  Iredell             quadratic interpolation
2027! 1999-03-01  Iredell             f90 module
2028!
2029! Usage:  call stmaq(the,pk,tma,qma)
2030!
2031!   Input argument list:
2032!     the        Real(krealfp) equivalent potential temperature in Kelvin
2033!     pk         Real(krealfp) pressure over 1e5 Pa to the kappa power
2034!
2035!   Output argument list:
2036!     tmaq       Real(krealfp) parcel temperature in Kelvin
2037!     qma        Real(krealfp) parcel specific humidity in kg/kg
2038!
2039! Attributes:
2040!   Language: Fortran 90.
2041!
2042!$$$
2043    implicit none
2044    real(krealfp),intent(in):: the,pk
2045    real(krealfp),intent(out):: tma,qma
2046    integer jx,jy
2047    real(krealfp) xj,yj,dxj,dyj
2048    real(krealfp) ft11,ft12,ft13,ft21,ft22,ft23,ft31,ft32,ft33
2049    real(krealfp) ftx1,ftx2,ftx3
2050    real(krealfp) q11,q12,q13,q21,q22,q23,q31,q32,q33,qx1,qx2,qx3
2051! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2052    xj=min(max(c1xma+c2xma*the,1._krealfp),real(nxma,krealfp))
2053    yj=min(max(c1yma+c2yma*pk,1._krealfp),real(nyma,krealfp))
2054    jx=min(max(nint(xj),2),nxma-1)
2055    jy=min(max(nint(yj),2),nyma-1)
2056    dxj=xj-jx
2057    dyj=yj-jy
2058    ft11=tbtma(jx-1,jy-1)
2059    ft12=tbtma(jx-1,jy)
2060    ft13=tbtma(jx-1,jy+1)
2061    ft21=tbtma(jx,jy-1)
2062    ft22=tbtma(jx,jy)
2063    ft23=tbtma(jx,jy+1)
2064    ft31=tbtma(jx+1,jy-1)
2065    ft32=tbtma(jx+1,jy)
2066    ft33=tbtma(jx+1,jy+1)
2067    ftx1=(((ft31+ft11)/2-ft21)*dxj+(ft31-ft11)/2)*dxj+ft21
2068    ftx2=(((ft32+ft12)/2-ft22)*dxj+(ft32-ft12)/2)*dxj+ft22
2069    ftx3=(((ft33+ft13)/2-ft23)*dxj+(ft33-ft13)/2)*dxj+ft23
2070    tma=(((ftx3+ftx1)/2-ftx2)*dyj+(ftx3-ftx1)/2)*dyj+ftx2
2071    q11=tbqma(jx-1,jy-1)
2072    q12=tbqma(jx-1,jy)
2073    q13=tbqma(jx-1,jy+1)
2074    q21=tbqma(jx,jy-1)
2075    q22=tbqma(jx,jy)
2076    q23=tbqma(jx,jy+1)
2077    q31=tbqma(jx+1,jy-1)
2078    q32=tbqma(jx+1,jy)
2079    q33=tbqma(jx+1,jy+1)
2080    qx1=(((q31+q11)/2-q21)*dxj+(q31-q11)/2)*dxj+q21
2081    qx2=(((q32+q12)/2-q22)*dxj+(q32-q12)/2)*dxj+q22
2082    qx3=(((q33+q13)/2-q23)*dxj+(q33-q13)/2)*dxj+q23
2083    qma=(((qx3+qx1)/2-qx2)*dyj+(qx3-qx1)/2)*dyj+qx2
2084! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2085  end subroutine
2086!-------------------------------------------------------------------------------
2087! elemental subroutine stmax(the,pk,tma,qma)
2088  subroutine stmax(the,pk,tma,qma)
2089!$$$     Subprogram Documentation Block
2090!
2091! Subprogram: stmax        Compute moist adiabat temperature
2092!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2093!
2094! Abstract: Exactly compute temperature and humidity of a parcel
2095!   lifted up a moist adiabat from equivalent potential temperature
2096!   at the LCL and pressure over 1e5 Pa to the kappa power.
2097!   An approximate parcel temperature for subprogram stmaxg
2098!   is obtained using stma so gtma must be already called.
2099!   See documentation for stmaxg for details.
2100!
2101! Program History Log:
2102!   91-05-07  Iredell             made into inlinable function
2103!   94-12-30  Iredell             exact computation
2104! 1999-03-01  Iredell             f90 module
2105!
2106! Usage:  call stmax(the,pk,tma,qma)
2107!
2108!   Input argument list:
2109!     the        Real(krealfp) equivalent potential temperature in Kelvin
2110!     pk         Real(krealfp) pressure over 1e5 Pa to the kappa power
2111!
2112!   Output argument list:
2113!     tma        Real(krealfp) parcel temperature in Kelvin
2114!     qma        Real(krealfp) parcel specific humidity in kg/kg
2115!
2116! Subprograms called:
2117!   (stma)     inlinable subprogram to compute parcel temperature
2118!   (stmaxg)   inlinable subprogram to compute parcel temperature
2119!
2120! Attributes:
2121!   Language: Fortran 90.
2122!
2123!$$$
2124    implicit none
2125    real(krealfp),intent(in):: the,pk
2126    real(krealfp),intent(out):: tma,qma
2127    real(krealfp) tg,qg
2128! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2129    call stma(the,pk,tg,qg)
2130    call stmaxg(tg,the,pk,tma,qma)
2131! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2132  end subroutine
2133!-------------------------------------------------------------------------------
2134! elemental subroutine stmaxg(tg,the,pk,tma,qma)
2135  subroutine stmaxg(tg,the,pk,tma,qma)
2136!$$$     Subprogram Documentation Block
2137!
2138! Subprogram: stmaxg       Compute moist adiabat temperature
2139!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2140!
2141! Abstract: exactly compute temperature and humidity of a parcel
2142!   lifted up a moist adiabat from equivalent potential temperature
2143!   at the LCL and pressure over 1e5 Pa to the kappa power.
2144!   A guess parcel temperature must be provided.
2145!   Equivalent potential temperature is constant for a saturated parcel
2146!   rising adiabatically up a moist adiabat when the heat and mass
2147!   of the condensed water are neglected.  Ice is also neglected.
2148!   The formula for equivalent potential temperature (Holton) is
2149!       the=t*(pd**(-rocp))*exp(el*eps*pv/(cp*t*pd))
2150!   where t is the temperature, pv is the saturated vapor pressure,
2151!   pd is the dry pressure p-pv, el is the temperature dependent
2152!   latent heat of condensation hvap+dldt*(t-ttp), and other values
2153!   are physical constants defined in parameter statements in the code.
2154!   The formula is inverted by iterating Newtonian approximations
2155!   for each the and p until t is found to within 1.e-4 Kelvin.
2156!   The specific humidity is then computed from pv and pd.
2157!   This subprogram can be expanded inline in the calling routine.
2158!
2159! Program History Log:
2160!   91-05-07  Iredell             made into inlinable function
2161!   94-12-30  Iredell             exact computation
2162! 1999-03-01  Iredell             f90 module
2163!
2164! Usage:  call stmaxg(tg,the,pk,tma,qma)
2165!
2166!   Input argument list:
2167!     tg         Real(krealfp) guess parcel temperature in Kelvin
2168!     the        Real(krealfp) equivalent potential temperature in Kelvin
2169!     pk         Real(krealfp) pressure over 1e5 Pa to the kappa power
2170!
2171!   Output argument list:
2172!     tma        Real(krealfp) parcel temperature in Kelvin
2173!     qma        Real(krealfp) parcel specific humidity in kg/kg
2174!
2175! Attributes:
2176!   Language: Fortran 90.
2177!
2178!$$$
2179    implicit none
2180    real(krealfp),intent(in):: tg,the,pk
2181    real(krealfp),intent(out):: tma,qma
2182    real(krealfp),parameter:: terrm=1.e-4
2183    real(krealfp) t,p,tr,pv,pd,el,expo,thet,dthet,terr
2184    integer i
2185! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2186    t=tg
2187    p=pk**con_cpor
2188    do i=1,100
2189      tr=con_ttp/t
2190      pv=psatb*(tr**con_xpona)*exp(con_xponb*(1.-tr))
2191      pd=p-pv
2192      el=con_hvap+con_dldt*(t-con_ttp)
2193      expo=el*con_eps*pv/(con_cp*t*pd)
2194      thet=t*pd**(-con_rocp)*exp(expo)
2195      dthet=thet/t*(1.+expo*(con_dldt*t/el+el*p/(con_rv*t*pd)))
2196      terr=(thet-the)/dthet
2197      t=t-terr
2198      if(abs(terr).le.terrm) exit
2199    enddo
2200    tma=t
2201    tr=con_ttp/t
2202    pv=psatb*(tr**con_xpona)*exp(con_xponb*(1.-tr))
2203    pd=p-pv
2204    qma=con_eps*pv/(pd+con_eps*pv)
2205! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2206  end subroutine
2207!-------------------------------------------------------------------------------
2208  subroutine gpkap
2209!$$$   Subprogram  documentation  block
2210!
2211! Subprogram: gpkap        Compute coefficients for p**kappa
2212!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2213!
2214! Abstract: Computes pressure to the kappa table as a function of pressure
2215!   for the table lookup function fpkap.
2216!   Exact pressure to the kappa values are calculated in subprogram fpkapx.
2217!   The current implementation computes a table with a length
2218!   of 5501 for pressures ranging up to 110000 Pascals.
2219!
2220! Program History Log:
2221!   94-12-30  Iredell
2222! 1999-03-01  Iredell             f90 module
2223! 1999-03-24  Iredell             table lookup
2224!
2225! Usage:  call gpkap
2226!
2227! Subprograms called:
2228!   fpkapx     function to compute exact pressure to the kappa
2229!
2230! Attributes:
2231!   Language: Fortran 90.
2232!
2233!$$$
2234    implicit none
2235    integer jx
2236    real(krealfp) xmin,xmax,xinc,x,p
2237! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2238    xmin=0._krealfp
2239    xmax=110000._krealfp
2240    xinc=(xmax-xmin)/(nxpkap-1)
2241    c1xpkap=1.-xmin/xinc
2242    c2xpkap=1./xinc
2243    do jx=1,nxpkap
2244      x=xmin+(jx-1)*xinc
2245      p=x
2246      tbpkap(jx)=fpkapx(p)
2247    enddo
2248! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2249  end subroutine
2250!-------------------------------------------------------------------------------
2251! elemental function fpkap(p)
2252  function fpkap(p)
2253!$$$     Subprogram Documentation Block
2254!
2255! Subprogram: fpkap        raise pressure to the kappa power.
2256!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2257!
2258! Abstract: Raise pressure over 1e5 Pa to the kappa power.
2259!   A linear interpolation is done between values in a lookup table
2260!   computed in gpkap. See documentation for fpkapx for details.
2261!   Input values outside table range are reset to table extrema.
2262!   The interpolation accuracy ranges from 9 decimal places
2263!   at 100000 Pascals to 5 decimal places at 1000 Pascals.
2264!   On the Cray, fpkap is over 5 times faster than exact calculation.
2265!   This function should be expanded inline in the calling routine.
2266!
2267! Program History Log:
2268!   91-05-07  Iredell             made into inlinable function
2269!   94-12-30  Iredell             standardized kappa,
2270!                                 increased range and accuracy
2271! 1999-03-01  Iredell             f90 module
2272! 1999-03-24  Iredell             table lookup
2273!
2274! Usage:   pkap=fpkap(p)
2275!
2276!   Input argument list:
2277!     p          Real(krealfp) pressure in Pascals
2278!
2279!   Output argument list:
2280!     fpkap      Real(krealfp) p over 1e5 Pa to the kappa power
2281!
2282! Attributes:
2283!   Language: Fortran 90.
2284!
2285!$$$
2286    implicit none
2287    real(krealfp) fpkap
2288    real(krealfp),intent(in):: p
2289    integer jx
2290    real(krealfp) xj
2291! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2292    xj=min(max(c1xpkap+c2xpkap*p,1._krealfp),real(nxpkap,krealfp))
2293    jx=min(xj,nxpkap-1._krealfp)
2294    fpkap=tbpkap(jx)+(xj-jx)*(tbpkap(jx+1)-tbpkap(jx))
2295! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2296  end function
2297!-------------------------------------------------------------------------------
2298! elemental function fpkapq(p)
2299  function fpkapq(p)
2300!$$$     Subprogram Documentation Block
2301!
2302! Subprogram: fpkapq       raise pressure to the kappa power.
2303!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2304!
2305! Abstract: Raise pressure over 1e5 Pa to the kappa power.
2306!   A quadratic interpolation is done between values in a lookup table
2307!   computed in gpkap. see documentation for fpkapx for details.
2308!   Input values outside table range are reset to table extrema.
2309!   The interpolation accuracy ranges from 12 decimal places
2310!   at 100000 Pascals to 7 decimal places at 1000 Pascals.
2311!   On the Cray, fpkap is over 4 times faster than exact calculation.
2312!   This function should be expanded inline in the calling routine.
2313!
2314! Program History Log:
2315!   91-05-07  Iredell             made into inlinable function
2316!   94-12-30  Iredell             standardized kappa,
2317!                                 increased range and accuracy
2318! 1999-03-01  Iredell             f90 module
2319! 1999-03-24  Iredell             table lookup
2320!
2321! Usage:   pkap=fpkapq(p)
2322!
2323!   Input argument list:
2324!     p          Real(krealfp) pressure in Pascals
2325!
2326!   Output argument list:
2327!     fpkapq     Real(krealfp) p over 1e5 Pa to the kappa power
2328!
2329! Attributes:
2330!   Language: Fortran 90.
2331!
2332!$$$
2333    implicit none
2334    real(krealfp) fpkapq
2335    real(krealfp),intent(in):: p
2336    integer jx
2337    real(krealfp) xj,dxj,fj1,fj2,fj3
2338! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2339    xj=min(max(c1xpkap+c2xpkap*p,1._krealfp),real(nxpkap,krealfp))
2340    jx=min(max(nint(xj),2),nxpkap-1)
2341    dxj=xj-jx
2342    fj1=tbpkap(jx-1)
2343    fj2=tbpkap(jx)
2344    fj3=tbpkap(jx+1)
2345    fpkapq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
2346! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2347  end function
2348!-------------------------------------------------------------------------------
2349  function fpkapo(p)
2350!$$$   Subprogram  documentation  block
2351!
2352! Subprogram: fpkapo       raise surface pressure to the kappa power.
2353!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2354!
2355! Abstract: Raise surface pressure over 1e5 Pa to the kappa power
2356!   using a rational weighted chebyshev approximation.
2357!   The numerator is of order 2 and the denominator is of order 4.
2358!   The pressure range is 40000-110000 Pa and kappa is defined in fpkapx.
2359!   The accuracy of this approximation is almost 8 decimal places.
2360!   On the Cray, fpkap is over 10 times faster than exact calculation.
2361!   This function should be expanded inline in the calling routine.
2362!
2363! Program History Log:
2364!   91-05-07  Iredell             made into inlinable function
2365!   94-12-30  Iredell             standardized kappa,
2366!                                 increased range and accuracy
2367! 1999-03-01  Iredell             f90 module
2368!
2369! Usage:  pkap=fpkapo(p)
2370!
2371!   Input argument list:
2372!     p          Real(krealfp) surface pressure in Pascals
2373!                p should be in the range 40000 to 110000
2374!
2375!   Output argument list:
2376!     fpkapo     Real(krealfp) p over 1e5 Pa to the kappa power
2377!
2378! Attributes:
2379!   Language: Fortran 90.
2380!
2381!$$$
2382    implicit none
2383    real(krealfp) fpkapo
2384    real(krealfp),intent(in):: p
2385    integer,parameter:: nnpk=2,ndpk=4
2386    real(krealfp):: cnpk(0:nnpk)=(/3.13198449e-1,5.78544829e-2,&
2387                                         8.35491871e-4/)
2388    real(krealfp):: cdpk(0:ndpk)=(/1.,8.15968401e-2,5.72839518e-4,&
2389                                         -4.86959812e-7,5.24459889e-10/)
2390    integer n
2391    real(krealfp) pkpa,fnpk,fdpk
2392! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2393    pkpa=p*1.e-3_krealfp
2394    fnpk=cnpk(nnpk)
2395    do n=nnpk-1,0,-1
2396      fnpk=pkpa*fnpk+cnpk(n)
2397    enddo
2398    fdpk=cdpk(ndpk)
2399    do n=ndpk-1,0,-1
2400      fdpk=pkpa*fdpk+cdpk(n)
2401    enddo
2402    fpkapo=fnpk/fdpk
2403! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2404  end function
2405!-------------------------------------------------------------------------------
2406! elemental function fpkapx(p)
2407  function fpkapx(p)
2408!$$$   Subprogram  documentation  block
2409!
2410! Subprogram: fpkapx       raise pressure to the kappa power.
2411!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2412!
2413! Abstract: raise pressure over 1e5 Pa to the kappa power.
2414!   Kappa is equal to rd/cp where rd and cp are physical constants.
2415!   This function should be expanded inline in the calling routine.
2416!
2417! Program History Log:
2418!   94-12-30  Iredell             made into inlinable function
2419! 1999-03-01  Iredell             f90 module
2420!
2421! Usage:  pkap=fpkapx(p)
2422!
2423!   Input argument list:
2424!     p          Real(krealfp) pressure in Pascals
2425!
2426!   Output argument list:
2427!     fpkapx     Real(krealfp) p over 1e5 Pa to the kappa power
2428!
2429! Attributes:
2430!   Language: Fortran 90.
2431!
2432!$$$
2433    implicit none
2434    real(krealfp) fpkapx
2435    real(krealfp),intent(in):: p
2436! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2437    fpkapx=(p/1.e5_krealfp)**con_rocp
2438! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2439  end function
2440!-------------------------------------------------------------------------------
2441  subroutine grkap
2442!$$$   Subprogram  documentation  block
2443!
2444! Subprogram: grkap        Compute coefficients for p**(1/kappa)
2445!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2446!
2447! Abstract: Computes pressure to the 1/kappa table as a function of pressure
2448!   for the table lookup function frkap.
2449!   Exact pressure to the 1/kappa values are calculated in subprogram frkapx.
2450!   The current implementation computes a table with a length
2451!   of 5501 for pressures ranging up to 110000 Pascals.
2452!
2453! Program History Log:
2454!   94-12-30  Iredell
2455! 1999-03-01  Iredell             f90 module
2456! 1999-03-24  Iredell             table lookup
2457!
2458! Usage:  call grkap
2459!
2460! Subprograms called:
2461!   frkapx     function to compute exact pressure to the 1/kappa
2462!
2463! Attributes:
2464!   Language: Fortran 90.
2465!
2466!$$$
2467    implicit none
2468    integer jx
2469    real(krealfp) xmin,xmax,xinc,x,p
2470! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2471    xmin=0._krealfp
2472    xmax=fpkapx(110000._krealfp)
2473    xinc=(xmax-xmin)/(nxrkap-1)
2474    c1xrkap=1.-xmin/xinc
2475    c2xrkap=1./xinc
2476    do jx=1,nxrkap
2477      x=xmin+(jx-1)*xinc
2478      p=x
2479      tbrkap(jx)=frkapx(p)
2480    enddo
2481! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2482  end subroutine
2483!-------------------------------------------------------------------------------
2484! elemental function frkap(pkap)
2485  function frkap(pkap)
2486!$$$     Subprogram Documentation Block
2487!
2488! Subprogram: frkap        raise pressure to the 1/kappa power.
2489!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2490!
2491! Abstract: Raise pressure over 1e5 Pa to the 1/kappa power.
2492!   A linear interpolation is done between values in a lookup table
2493!   computed in grkap. See documentation for frkapx for details.
2494!   Input values outside table range are reset to table extrema.
2495!   The interpolation accuracy is better than 7 decimal places.
2496!   On the IBM, fpkap is about 4 times faster than exact calculation.
2497!   This function should be expanded inline in the calling routine.
2498!
2499! Program History Log:
2500!   91-05-07  Iredell             made into inlinable function
2501!   94-12-30  Iredell             standardized kappa,
2502!                                 increased range and accuracy
2503! 1999-03-01  Iredell             f90 module
2504! 1999-03-24  Iredell             table lookup
2505!
2506! Usage:   p=frkap(pkap)
2507!
2508!   Input argument list:
2509!     pkap       Real(krealfp) p over 1e5 Pa to the kappa power
2510!
2511!   Output argument list:
2512!     frkap      Real(krealfp) pressure in Pascals
2513!
2514! Attributes:
2515!   Language: Fortran 90.
2516!
2517!$$$
2518    implicit none
2519    real(krealfp) frkap
2520    real(krealfp),intent(in):: pkap
2521    integer jx
2522    real(krealfp) xj
2523! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2524    xj=min(max(c1xrkap+c2xrkap*pkap,1._krealfp),real(nxrkap,krealfp))
2525    jx=min(xj,nxrkap-1._krealfp)
2526    frkap=tbrkap(jx)+(xj-jx)*(tbrkap(jx+1)-tbrkap(jx))
2527! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2528  end function
2529!-------------------------------------------------------------------------------
2530! elemental function frkapq(pkap)
2531  function frkapq(pkap)
2532!$$$     Subprogram Documentation Block
2533!
2534! Subprogram: frkapq       raise pressure to the 1/kappa power.
2535!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2536!
2537! Abstract: Raise pressure over 1e5 Pa to the 1/kappa power.
2538!   A quadratic interpolation is done between values in a lookup table
2539!   computed in grkap. see documentation for frkapx for details.
2540!   Input values outside table range are reset to table extrema.
2541!   The interpolation accuracy is better than 11 decimal places.
2542!   On the IBM, fpkap is almost 4 times faster than exact calculation.
2543!   This function should be expanded inline in the calling routine.
2544!
2545! Program History Log:
2546!   91-05-07  Iredell             made into inlinable function
2547!   94-12-30  Iredell             standardized kappa,
2548!                                 increased range and accuracy
2549! 1999-03-01  Iredell             f90 module
2550! 1999-03-24  Iredell             table lookup
2551!
2552! Usage:   p=frkapq(pkap)
2553!
2554!   Input argument list:
2555!     pkap       Real(krealfp) p over 1e5 Pa to the kappa power
2556!
2557!   Output argument list:
2558!     frkapq     Real(krealfp) pressure in Pascals
2559!
2560! Attributes:
2561!   Language: Fortran 90.
2562!
2563!$$$
2564    implicit none
2565    real(krealfp) frkapq
2566    real(krealfp),intent(in):: pkap
2567    integer jx
2568    real(krealfp) xj,dxj,fj1,fj2,fj3
2569! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2570    xj=min(max(c1xrkap+c2xrkap*pkap,1._krealfp),real(nxrkap,krealfp))
2571    jx=min(max(nint(xj),2),nxrkap-1)
2572    dxj=xj-jx
2573    fj1=tbrkap(jx-1)
2574    fj2=tbrkap(jx)
2575    fj3=tbrkap(jx+1)
2576    frkapq=(((fj3+fj1)/2-fj2)*dxj+(fj3-fj1)/2)*dxj+fj2
2577! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2578  end function
2579!-------------------------------------------------------------------------------
2580! elemental function frkapx(pkap)
2581  function frkapx(pkap)
2582!$$$   Subprogram  documentation  block
2583!
2584! Subprogram: frkapx       raise pressure to the 1/kappa power.
2585!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2586!
2587! Abstract: raise pressure over 1e5 Pa to the 1/kappa power.
2588!   Kappa is equal to rd/cp where rd and cp are physical constants.
2589!   This function should be expanded inline in the calling routine.
2590!
2591! Program History Log:
2592!   94-12-30  Iredell             made into inlinable function
2593! 1999-03-01  Iredell             f90 module
2594!
2595! Usage:  p=frkapx(pkap)
2596!
2597!   Input argument list:
2598!     pkap       Real(krealfp) p over 1e5 Pa to the kappa power
2599!
2600!   Output argument list:
2601!     frkapx     Real(krealfp) pressure in Pascals
2602!
2603! Attributes:
2604!   Language: Fortran 90.
2605!
2606!$$$
2607    implicit none
2608    real(krealfp) frkapx
2609    real(krealfp),intent(in):: pkap
2610! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2611    frkapx=pkap**(1/con_rocp)*1.e5_krealfp
2612! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2613  end function
2614!-------------------------------------------------------------------------------
2615  subroutine gtlcl
2616!$$$     Subprogram Documentation Block
2617!
2618! Subprogram: gtlcl        Compute equivalent potential temperature table
2619!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2620!
2621! Abstract: Compute lifting condensation level temperature table
2622!   as a function of temperature and dewpoint depression for function ftlcl.
2623!   Lifting condensation level temperature is calculated in subprogram ftlclx
2624!   The current implementation computes a table with a first dimension
2625!   of 151 for temperatures ranging from 180.0 to 330.0 Kelvin
2626!   and a second dimension of 61 for dewpoint depression ranging from
2627!   0 to 60 Kelvin.
2628!
2629! Program History Log:
2630! 1999-03-01  Iredell             f90 module
2631!
2632! Usage:  call gtlcl
2633!
2634! Subprograms called:
2635!   (ftlclx)    inlinable function to compute LCL temperature
2636!
2637! Attributes:
2638!   Language: Fortran 90.
2639!
2640!$$$
2641    implicit none
2642    integer jx,jy
2643    real(krealfp) xmin,xmax,ymin,ymax,xinc,yinc,x,y,tdpd,t
2644! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2645    xmin=180._krealfp
2646    xmax=330._krealfp
2647    ymin=0._krealfp
2648    ymax=60._krealfp
2649    xinc=(xmax-xmin)/(nxtlcl-1)
2650    c1xtlcl=1.-xmin/xinc
2651    c2xtlcl=1./xinc
2652    yinc=(ymax-ymin)/(nytlcl-1)
2653    c1ytlcl=1.-ymin/yinc
2654    c2ytlcl=1./yinc
2655    do jy=1,nytlcl
2656      y=ymin+(jy-1)*yinc
2657      tdpd=y
2658      do jx=1,nxtlcl
2659        x=xmin+(jx-1)*xinc
2660        t=x
2661        tbtlcl(jx,jy)=ftlclx(t,tdpd)
2662      enddo
2663    enddo
2664! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2665  end subroutine
2666!-------------------------------------------------------------------------------
2667! elemental function ftlcl(t,tdpd)
2668  function ftlcl(t,tdpd)
2669!$$$     Subprogram Documentation Block
2670!
2671! Subprogram: ftlcl        Compute LCL temperature
2672!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2673!
2674! Abstract: Compute temperature at the lifting condensation level
2675!   from temperature and dewpoint depression.
2676!   A bilinear interpolation is done between values in a lookup table
2677!   computed in gtlcl. See documentation for ftlclx for details.
2678!   Input values outside table range are reset to table extrema.
2679!   The interpolation accuracy is better than 0.0005 Kelvin.
2680!   On the Cray, ftlcl is ? times faster than exact calculation.
2681!   This function should be expanded inline in the calling routine.
2682!
2683! Program History Log:
2684! 1999-03-01  Iredell             f90 module
2685!
2686! Usage:   tlcl=ftlcl(t,tdpd)
2687!
2688!   Input argument list:
2689!     t          Real(krealfp) LCL temperature in Kelvin
2690!     tdpd       Real(krealfp) dewpoint depression in Kelvin
2691!
2692!   Output argument list:
2693!     ftlcl      Real(krealfp) temperature at the LCL in Kelvin
2694!
2695! Attributes:
2696!   Language: Fortran 90.
2697!
2698!$$$
2699    implicit none
2700    real(krealfp) ftlcl
2701    real(krealfp),intent(in):: t,tdpd
2702    integer jx,jy
2703    real(krealfp) xj,yj,ftx1,ftx2
2704! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2705    xj=min(max(c1xtlcl+c2xtlcl*t,1._krealfp),real(nxtlcl,krealfp))
2706    yj=min(max(c1ytlcl+c2ytlcl*tdpd,1._krealfp),real(nytlcl,krealfp))
2707    jx=min(xj,nxtlcl-1._krealfp)
2708    jy=min(yj,nytlcl-1._krealfp)
2709    ftx1=tbtlcl(jx,jy)+(xj-jx)*(tbtlcl(jx+1,jy)-tbtlcl(jx,jy))
2710    ftx2=tbtlcl(jx,jy+1)+(xj-jx)*(tbtlcl(jx+1,jy+1)-tbtlcl(jx,jy+1))
2711    ftlcl=ftx1+(yj-jy)*(ftx2-ftx1)
2712! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2713  end function
2714!-------------------------------------------------------------------------------
2715! elemental function ftlclq(t,tdpd)
2716  function ftlclq(t,tdpd)
2717!$$$     Subprogram Documentation Block
2718!
2719! Subprogram: ftlclq       Compute LCL temperature
2720!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2721!
2722! Abstract: Compute temperature at the lifting condensation level
2723!   from temperature and dewpoint depression.
2724!   A biquadratic interpolation is done between values in a lookup table
2725!   computed in gtlcl. see documentation for ftlclx for details.
2726!   Input values outside table range are reset to table extrema.
2727!   The interpolation accuracy is better than 0.000003 Kelvin.
2728!   On the Cray, ftlclq is ? times faster than exact calculation.
2729!   This function should be expanded inline in the calling routine.
2730!
2731! Program History Log:
2732! 1999-03-01  Iredell             f90 module
2733!
2734! Usage:   tlcl=ftlclq(t,tdpd)
2735!
2736!   Input argument list:
2737!     t          Real(krealfp) LCL temperature in Kelvin
2738!     tdpd       Real(krealfp) dewpoint depression in Kelvin
2739!
2740!   Output argument list:
2741!     ftlcl      Real(krealfp) temperature at the LCL in Kelvin
2742!
2743! Attributes:
2744!   Language: Fortran 90.
2745!
2746!$$$
2747    implicit none
2748    real(krealfp) ftlclq
2749    real(krealfp),intent(in):: t,tdpd
2750    integer jx,jy
2751    real(krealfp) xj,yj,dxj,dyj
2752    real(krealfp) ft11,ft12,ft13,ft21,ft22,ft23,ft31,ft32,ft33
2753    real(krealfp) ftx1,ftx2,ftx3
2754! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2755    xj=min(max(c1xtlcl+c2xtlcl*t,1._krealfp),real(nxtlcl,krealfp))
2756    yj=min(max(c1ytlcl+c2ytlcl*tdpd,1._krealfp),real(nytlcl,krealfp))
2757    jx=min(max(nint(xj),2),nxtlcl-1)
2758    jy=min(max(nint(yj),2),nytlcl-1)
2759    dxj=xj-jx
2760    dyj=yj-jy
2761    ft11=tbtlcl(jx-1,jy-1)
2762    ft12=tbtlcl(jx-1,jy)
2763    ft13=tbtlcl(jx-1,jy+1)
2764    ft21=tbtlcl(jx,jy-1)
2765    ft22=tbtlcl(jx,jy)
2766    ft23=tbtlcl(jx,jy+1)
2767    ft31=tbtlcl(jx+1,jy-1)
2768    ft32=tbtlcl(jx+1,jy)
2769    ft33=tbtlcl(jx+1,jy+1)
2770    ftx1=(((ft31+ft11)/2-ft21)*dxj+(ft31-ft11)/2)*dxj+ft21
2771    ftx2=(((ft32+ft12)/2-ft22)*dxj+(ft32-ft12)/2)*dxj+ft22
2772    ftx3=(((ft33+ft13)/2-ft23)*dxj+(ft33-ft13)/2)*dxj+ft23
2773    ftlclq=(((ftx3+ftx1)/2-ftx2)*dyj+(ftx3-ftx1)/2)*dyj+ftx2
2774! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2775  end function
2776!-------------------------------------------------------------------------------
2777  function ftlclo(t,tdpd)
2778!$$$   Subprogram  documentation  block
2779!
2780! Subprogram: ftlclo       Compute LCL temperature.
2781!   Author: Phillips         org: w/NMC2X2   Date: 29 dec 82
2782!
2783! Abstract: Compute temperature at the lifting condensation level
2784!   from temperature and dewpoint depression.  the formula used is
2785!   a polynomial taken from Phillips mstadb routine which empirically
2786!   approximates the original exact implicit relationship.
2787!   (This kind of approximation is customary (inman, 1969), but
2788!   the original source for this particular one is not yet known. -MI)
2789!   Its accuracy is about 0.03 Kelvin for a dewpoint depression of 30.
2790!   This function should be expanded inline in the calling routine.
2791!
2792! Program History Log:
2793!   91-05-07  Iredell             made into inlinable function
2794! 1999-03-01  Iredell             f90 module
2795!
2796! Usage:  tlcl=ftlclo(t,tdpd)
2797!
2798!   Input argument list:
2799!     t          Real(krealfp) temperature in Kelvin
2800!     tdpd       Real(krealfp) dewpoint depression in Kelvin
2801!
2802!   Output argument list:
2803!     ftlclo     Real(krealfp) temperature at the LCL in Kelvin
2804!
2805! Attributes:
2806!   Language: Fortran 90.
2807!
2808!$$$
2809    implicit none
2810    real(krealfp) ftlclo
2811    real(krealfp),intent(in):: t,tdpd
2812    real(krealfp),parameter:: clcl1= 0.954442e+0,clcl2= 0.967772e-3,&
2813                                    clcl3=-0.710321e-3,clcl4=-0.270742e-5
2814! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2815    ftlclo=t-tdpd*(clcl1+clcl2*t+tdpd*(clcl3+clcl4*t))
2816! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2817  end function
2818!-------------------------------------------------------------------------------
2819! elemental function ftlclx(t,tdpd)
2820  function ftlclx(t,tdpd)
2821!$$$   Subprogram  documentation  block
2822!
2823! Subprogram: ftlclx       Compute LCL temperature.
2824!   Author: Iredell          org: w/NMC2X2   Date: 25 March 1999
2825!
2826! Abstract: Compute temperature at the lifting condensation level
2827!   from temperature and dewpoint depression.  A parcel lifted
2828!   adiabatically becomes saturated at the lifting condensation level.
2829!   The water model assumes a perfect gas, constant specific heats
2830!   for gas and liquid, and neglects the volume of the liquid.
2831!   The model does account for the variation of the latent heat
2832!   of condensation with temperature.  The ice option is not included.
2833!   The Clausius-Clapeyron equation is integrated from the triple point
2834!   to get the formulas
2835!       pvlcl=con_psat*(trlcl**xa)*exp(xb*(1.-trlcl))
2836!       pvdew=con_psat*(trdew**xa)*exp(xb*(1.-trdew))
2837!   where pvlcl is the saturated parcel vapor pressure at the LCL,
2838!   pvdew is the unsaturated parcel vapor pressure initially,
2839!   trlcl is ttp/tlcl and trdew is ttp/tdew.  The adiabatic lifting
2840!   of the parcel is represented by the following formula
2841!       pvdew=pvlcl*(t/tlcl)**(1/kappa)
2842!   This formula is inverted by iterating Newtonian approximations
2843!   until tlcl is found to within 1.e-6 Kelvin.  Note that the minimum
2844!   returned temperature is 180 Kelvin.
2845!
2846! Program History Log:
2847! 1999-03-25  Iredell
2848!
2849! Usage:  tlcl=ftlclx(t,tdpd)
2850!
2851!   Input argument list:
2852!     t          Real(krealfp) temperature in Kelvin
2853!     tdpd       Real(krealfp) dewpoint depression in Kelvin
2854!
2855!   Output argument list:
2856!     ftlclx     Real(krealfp) temperature at the LCL in Kelvin
2857!
2858! Attributes:
2859!   Language: Fortran 90.
2860!
2861!$$$
2862    implicit none
2863    real(krealfp) ftlclx
2864    real(krealfp),intent(in):: t,tdpd
2865    real(krealfp),parameter:: terrm=1.e-4,tlmin=180.,tlminx=tlmin-5.
2866    real(krealfp) tr,pvdew,tlcl,ta,pvlcl,el,dpvlcl,terr,terrp
2867    integer i
2868! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2869    tr=con_ttp/(t-tdpd)
2870    pvdew=con_psat*(tr**con_xpona)*exp(con_xponb*(1.-tr))
2871    tlcl=t-tdpd
2872    do i=1,100
2873      tr=con_ttp/tlcl
2874      ta=t/tlcl
2875      pvlcl=con_psat*(tr**con_xpona)*exp(con_xponb*(1.-tr))*ta**(1/con_rocp)
2876      el=con_hvap+con_dldt*(tlcl-con_ttp)
2877      dpvlcl=(el/(con_rv*t**2)+1/(con_rocp*tlcl))*pvlcl
2878      terr=(pvlcl-pvdew)/dpvlcl
2879      tlcl=tlcl-terr
2880      if(abs(terr).le.terrm.or.tlcl.lt.tlminx) exit
2881    enddo
2882    ftlclx=max(tlcl,tlmin)
2883! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2884  end function
2885!-------------------------------------------------------------------------------
2886  subroutine gfuncphys
2887!$$$     Subprogram Documentation Block
2888!
2889! Subprogram: gfuncphys    Compute all physics function tables
2890!   Author: N Phillips            w/NMC2X2   Date: 30 dec 82
2891!
2892! Abstract: Compute all physics function tables.  Lookup tables are
2893!   set up for computing saturation vapor pressure, dewpoint temperature,
2894!   equivalent potential temperature, moist adiabatic temperature and humidity,
2895!   pressure to the kappa, and lifting condensation level temperature.
2896!
2897! Program History Log:
2898! 1999-03-01  Iredell             f90 module
2899!
2900! Usage:  call gfuncphys
2901!
2902! Subprograms called:
2903!   gpvsl       compute saturation vapor pressure over liquid table
2904!   gpvsi       compute saturation vapor pressure over ice table
2905!   gpvs        compute saturation vapor pressure table
2906!   gtdpl       compute dewpoint temperature over liquid table
2907!   gtdpi       compute dewpoint temperature over ice table
2908!   gtdp        compute dewpoint temperature table
2909!   gthe        compute equivalent potential temperature table
2910!   gtma        compute moist adiabat tables
2911!   gpkap       compute pressure to the kappa table
2912!   grkap       compute pressure to the 1/kappa table
2913!   gtlcl       compute LCL temperature table
2914!
2915! Attributes:
2916!   Language: Fortran 90.
2917!
2918!$$$
2919    implicit none
2920! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2921    call gpvsl
2922    call gpvsi
2923    call gpvs
2924    call gtdpl
2925    call gtdpi
2926    call gtdp
2927    call gthe
2928    call gtma
2929    call gpkap
2930    call grkap
2931    call gtlcl
2932! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2933  end subroutine
2934!-------------------------------------------------------------------------------
2935end module module_gfs_funcphys
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