source: LMDZ6/branches/contrails/libf/phylmd/lmdz_lscp_tools.f90 @ 5760

Last change on this file since 5760 was 5717, checked in by aborella, 4 weeks ago

Merge with trunk r5653

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1MODULE lmdz_lscp_tools
2
3    IMPLICIT NONE
4
5CONTAINS
6
7!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
8SUBROUTINE FALLICE_VELOCITY(klon,iwc,temp,rho,pres,ptconv,ptpronclds,velo)
9
10    ! Ref:
11    ! Stubenrauch, C. J., Bonazzola, M.,
12    ! Protopapadaki, S. E., & Musat, I. (2019).
13    ! New cloud system metrics to assess bulk
14    ! ice cloud schemes in a GCM. Journal of
15    ! Advances in Modeling Earth Systems, 11,
16    ! 3212–3234. https://doi.org/10.1029/2019MS001642
17   
18    use lmdz_lscp_ini, only: iflag_vice, ffallv_con, ffallv_lsc, ffallv_issr
19    use lmdz_lscp_ini, only: cice_velo, dice_velo
20    use lmdz_lscp_ini, only: ok_bug_ice_fallspeed, eps
21
22    IMPLICIT NONE
23
24    INTEGER, INTENT(IN) :: klon
25    REAL, INTENT(IN), DIMENSION(klon) :: iwc       ! specific ice water content [kg/m3]
26    REAL, INTENT(IN), DIMENSION(klon) :: temp      ! temperature [K]
27    REAL, INTENT(IN), DIMENSION(klon) :: rho       ! dry air density [kg/m3]
28    REAL, INTENT(IN), DIMENSION(klon) :: pres      ! air pressure [Pa]
29    LOGICAL, INTENT(IN), DIMENSION(klon) :: ptconv    ! convective point  [-]
30    LOGICAL, INTENT(IN), DIMENSION(klon) :: ptpronclds! prognostic clouds point  [-]
31
32    REAL, INTENT(OUT), DIMENSION(klon) :: velo    ! fallspeed velocity of crystals [m/s]
33
34
35    INTEGER i
36    REAL logvm,iwcg,tempc,phpa,fallv_tun
37    REAL m2ice, m2snow, vmice, vmsnow
38    REAL aice, bice, asnow, bsnow
39   
40
41    DO i=1,klon
42
43        IF (ptconv(i)) THEN
44            fallv_tun=ffallv_con
45        ELSEIF (ptpronclds(i)) THEN
46            fallv_tun=ffallv_issr
47        ELSE
48            fallv_tun=ffallv_lsc
49        ENDIF
50
51        tempc=temp(i)-273.15 ! celcius temp
52        IF ( ok_bug_ice_fallspeed ) THEN
53            iwcg=MAX(iwc(i)*1000.,1E-3) ! iwc in g/m3. We set a minimum value to prevent from division by 0
54        ELSE
55            ! AB the threshold is way too high, we reduce it
56            iwcg=MAX(iwc(i)*1000.,eps) ! iwc in g/m3. We set a minimum value to prevent from division by 0
57        ENDIF
58        phpa=pres(i)/100.    ! pressure in hPa
59
60    IF (iflag_vice .EQ. 1) THEN
61        ! so-called 'empirical parameterization' in Stubenrauch et al. 2019
62        if (tempc .GE. -60.0) then
63
64            logvm= -0.0000414122*tempc*tempc*log(iwcg)-0.00538922*tempc*log(iwcg) &
65                    -0.0516344*log(iwcg)+0.00216078*tempc + 1.9714   
66            velo(i)=exp(logvm)
67        else
68            velo(i)=65.0*(iwcg**0.2)*(150./phpa)**0.15
69        endif
70       
71        velo(i)=fallv_tun*velo(i)/100.0 ! from cm/s to m/s
72
73    ELSE IF (iflag_vice .EQ. 2) THEN
74        ! so called  PSDM empirical coherent bulk ice scheme in Stubenrauch et al. 2019
75        aice=0.587
76        bice=2.45
77        asnow=0.0444
78        bsnow=2.1
79       
80        m2ice=((iwcg*0.001/aice)/(exp(13.6-bice*7.76+0.479*bice**2)* &
81                exp((-0.0361+bice*0.0151+0.00149*bice**2)*tempc)))   &
82                **(1./(0.807+bice*0.00581+0.0457*bice**2))
83
84        vmice=100.*1042.4*exp(13.6-(bice+1)*7.76+0.479*(bice+1.)**2)*exp((-0.0361+ &
85                 (bice+1.)*0.0151+0.00149*(bice+1.)**2)*tempc) &
86                 *(m2ice**(0.807+(bice+1.)*0.00581+0.0457*(bice+1.)**2))/(iwcg*0.001/aice)
87
88       
89        vmice=vmice*((1000./phpa)**0.2)
90     
91        m2snow=((iwcg*0.001/asnow)/(exp(13.6-bsnow*7.76+0.479*bsnow**2)* &
92               exp((-0.0361+bsnow*0.0151+0.00149*bsnow**2)*tempc)))         &
93               **(1./(0.807+bsnow*0.00581+0.0457*bsnow**2))
94
95
96        vmsnow=100.*14.3*exp(13.6-(bsnow+.416)*7.76+0.479*(bsnow+.416)**2)&
97                  *exp((-0.0361+(bsnow+.416)*0.0151+0.00149*(bsnow+.416)**2)*tempc)&
98                  *(m2snow**(0.807+(bsnow+.416)*0.00581+0.0457*(bsnow+.416)**2))/(iwcg*0.001/asnow)
99
100        vmsnow=vmsnow*((1000./phpa)**0.35)
101        velo(i)=fallv_tun*min(vmsnow,vmice)/100. ! to m/s
102
103    ELSE
104        ! By default, fallspeed velocity of ice crystals according to Heymsfield & Donner 1990
105        velo(i) = fallv_tun*cice_velo*((iwcg/1000.)**dice_velo)
106    ENDIF
107    ENDDO
108
109END SUBROUTINE FALLICE_VELOCITY
110!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
111
112!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
113SUBROUTINE ICEFRAC_LSCP(klon, temp, iflag_ice_thermo, distcltop, temp_cltop, icefrac, dicefracdT)
114!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
115 
116  ! Compute the ice fraction 1-xliq (see e.g.
117  ! Doutriaux-Boucher & Quaas 2004, section 2.2.)
118  ! as a function of temperature
119  ! see also Fig 3 of Madeleine et al. 2020, JAMES
120!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
121
122
123    USE print_control_mod, ONLY: lunout, prt_level
124    USE lmdz_lscp_ini, ONLY: t_glace_min, t_glace_max, exposant_glace, iflag_t_glace
125    USE lmdz_lscp_ini, ONLY : RTT, dist_liq, temp_nowater
126
127    IMPLICIT NONE
128
129
130    INTEGER, INTENT(IN)                 :: klon              ! number of horizontal grid points
131    REAL, INTENT(IN), DIMENSION(klon)   :: temp              ! temperature
132    REAL, INTENT(IN), DIMENSION(klon)   :: distcltop         ! distance to cloud top
133    REAL, INTENT(IN), DIMENSION(klon)   :: temp_cltop        ! temperature of cloud top
134    INTEGER, INTENT(IN)                 :: iflag_ice_thermo
135    REAL, INTENT(OUT), DIMENSION(klon)  :: icefrac
136    REAL, INTENT(OUT), DIMENSION(klon)  :: dicefracdT
137
138
139    INTEGER i
140    REAL    liqfrac_tmp, dicefrac_tmp
141    REAL    Dv, denomdep,beta,qsi,dqsidt
142    LOGICAL ice_thermo
143
144    CHARACTER (len = 20) :: modname = 'lscp_tools'
145    CHARACTER (len = 80) :: abort_message
146
147    IF ((iflag_t_glace.LT.2)) THEN !.OR. (iflag_t_glace.GT.6)) THEN
148       abort_message = 'lscp cannot be used if iflag_t_glace<2 or >6'
149       CALL abort_physic(modname,abort_message,1)
150    ENDIF
151
152    IF (.NOT.((iflag_ice_thermo .EQ. 1).OR.(iflag_ice_thermo .GE. 3))) THEN
153       abort_message = 'lscp cannot be used without ice thermodynamics'
154       CALL abort_physic(modname,abort_message,1)
155    ENDIF
156
157
158    DO i=1,klon
159 
160        ! old function with sole dependence upon temperature
161        IF (iflag_t_glace .EQ. 2) THEN
162            liqfrac_tmp = (temp(i)-t_glace_min) / (t_glace_max-t_glace_min)
163            liqfrac_tmp = MIN(MAX(liqfrac_tmp,0.0),1.0)
164            icefrac(i) = (1.0-liqfrac_tmp)**exposant_glace
165            IF (icefrac(i) .GT.0.) THEN
166                 dicefracdT(i)= exposant_glace * (icefrac(i)**(exposant_glace-1.)) &
167                           / (t_glace_min - t_glace_max)
168            ENDIF
169
170            IF ((icefrac(i).EQ.0).OR.(icefrac(i).EQ.1)) THEN
171                 dicefracdT(i)=0.
172            ENDIF
173
174        ENDIF
175
176        ! function of temperature used in CMIP6 physics
177        IF (iflag_t_glace .EQ. 3) THEN
178            liqfrac_tmp = (temp(i)-t_glace_min) / (t_glace_max-t_glace_min)
179            liqfrac_tmp = MIN(MAX(liqfrac_tmp,0.0),1.0)
180            icefrac(i) = 1.0-liqfrac_tmp**exposant_glace
181            IF ((icefrac(i) .GT.0.) .AND. (liqfrac_tmp .GT. 0.)) THEN
182                dicefracdT(i)= exposant_glace * ((liqfrac_tmp)**(exposant_glace-1.)) &
183                          / (t_glace_min - t_glace_max)
184            ELSE
185                dicefracdT(i)=0.
186            ENDIF
187        ENDIF
188
189        ! for iflag_t_glace .GE. 4, the liquid fraction depends upon temperature at cloud top
190        ! and then decreases with decreasing height
191
192        !with linear function of temperature at cloud top
193        IF (iflag_t_glace .EQ. 4) THEN 
194                liqfrac_tmp = (temp(i)-t_glace_min) / (t_glace_max-t_glace_min)
195                liqfrac_tmp = MIN(MAX(liqfrac_tmp,0.0),1.0)
196                icefrac(i)    =  MAX(MIN(1.,1.0 - liqfrac_tmp*exp(-distcltop(i)/dist_liq)),0.)
197                dicefrac_tmp = - temp(i)/(t_glace_max-t_glace_min)
198                dicefracdT(i) = dicefrac_tmp*exp(-distcltop(i)/dist_liq)
199                IF ((liqfrac_tmp .LE.0) .OR. (liqfrac_tmp .GE. 1)) THEN
200                        dicefracdT(i) = 0.
201                ENDIF
202        ENDIF
203
204        ! with CMIP6 function of temperature at cloud top
205        IF ((iflag_t_glace .EQ. 5) .OR. (iflag_t_glace .EQ. 7)) THEN
206                liqfrac_tmp = (temp(i)-t_glace_min) / (t_glace_max-t_glace_min)
207                liqfrac_tmp =  MIN(MAX(liqfrac_tmp,0.0),1.0)
208                liqfrac_tmp = liqfrac_tmp**exposant_glace
209                icefrac(i)  =  MAX(MIN(1.,1.0 - liqfrac_tmp*exp(-distcltop(i)/dist_liq)),0.)
210                IF ((liqfrac_tmp .LE.0) .OR. (liqfrac_tmp .GE. 1)) THEN
211                        dicefracdT(i) = 0.
212                ELSE
213                        dicefracdT(i) = exposant_glace*((liqfrac_tmp)**(exposant_glace-1.))/(t_glace_min- t_glace_max) &
214                                        *exp(-distcltop(i)/dist_liq)
215                ENDIF
216        ENDIF
217
218        ! with modified function of temperature at cloud top
219        ! to get largere values around 260 K, works well with t_glace_min = 241K
220        IF (iflag_t_glace .EQ. 6) THEN
221                IF (temp(i) .GT. t_glace_max) THEN
222                        liqfrac_tmp = 1.
223                ELSE
224                        liqfrac_tmp = -((temp(i)-t_glace_max) / (t_glace_max-t_glace_min))**2+1.
225                ENDIF
226                liqfrac_tmp  = MIN(MAX(liqfrac_tmp,0.0),1.0)
227                icefrac(i)   = MAX(MIN(1.,1.0 - liqfrac_tmp*exp(-distcltop(i)/dist_liq)),0.)       
228                IF ((liqfrac_tmp .LE.0) .OR. (liqfrac_tmp .GE. 1)) THEN
229                        dicefracdT(i) = 0.
230                ELSE
231                        dicefracdT(i) = 2*((temp(i)-t_glace_max) / (t_glace_max-t_glace_min))/(t_glace_max-t_glace_min) &
232                                  *exp(-distcltop(i)/dist_liq)
233                ENDIF
234        ENDIF
235
236        ! if temperature or temperature of cloud top <-40°C,
237        IF (iflag_t_glace .GE. 4) THEN
238                IF ((temp_cltop(i) .LE. temp_nowater) .AND. (temp(i) .LE. t_glace_max)) THEN
239                        icefrac(i) = 1.
240                        dicefracdT(i) = 0.
241                ENDIF
242        ENDIF
243     
244
245     ENDDO ! klon
246     RETURN
247 
248END SUBROUTINE ICEFRAC_LSCP
249!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
250
251
252SUBROUTINE ICEFRAC_LSCP_TURB(klon, dtime, pticefracturb, temp, pplay, paprsdn, paprsup, wvel, qice_ini, snowcld, snowfracld, qtot_incl, cldfra, tke,   &
253                             tke_dissip, sursat_e, invtau_e, qliq, qvap_cld, qice, icefrac, dicefracdT, cldfraliq, sigma2_icefracturb, mean_icefracturb)
254!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
255  ! Compute the liquid, ice and vapour content (+ice fraction) based
256  ! on turbulence (see Fields 2014, Furtado 2016, Raillard 2025)
257  ! L.Raillard (23/09/24)
258  ! E.Vignon (03/2025) : additional elements for treatment of convective
259  !                      boundary layer clouds
260!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
261
262
263   USE lmdz_lscp_ini, ONLY : prt_level, lunout
264   USE lmdz_lscp_ini, ONLY : RCPD, RLSTT, RLVTT, RLMLT, RVTMP2, RTT, RD, RG, RV, RPI
265   USE lmdz_lscp_ini, ONLY : seuil_neb, temp_nowater
266   USE lmdz_lscp_ini, ONLY : naero5, gamma_snwretro, gamma_taud, capa_crystal, rho_ice
267   USE lmdz_lscp_ini, ONLY : eps, snow_fallspeed
268
269   IMPLICIT NONE
270
271   INTEGER,   INTENT(IN)                           :: klon                !--number of horizontal grid points
272   REAL,      INTENT(IN)                           :: dtime               !--time step [s]
273   LOGICAL,   INTENT(IN),       DIMENSION(klon)    :: pticefracturb       !--grid points concerned by this routine 
274   REAL,      INTENT(IN),       DIMENSION(klon)    :: temp                !--temperature
275   REAL,      INTENT(IN),       DIMENSION(klon)    :: pplay               !--pressure in the middle of the layer           [Pa]
276   REAL,      INTENT(IN),       DIMENSION(klon)    :: paprsdn             !--pressure at the bottom interface of the layer [Pa]
277   REAL,      INTENT(IN),       DIMENSION(klon)    :: paprsup             !--pressure at the top interface of the layer    [Pa]
278   REAL,      INTENT(IN),       DIMENSION(klon)    :: wvel                !--vertical velocity                             [m/s]
279   REAL,      INTENT(IN),       DIMENSION(klon)    :: qtot_incl           !--specific total cloud water in-cloud content   [kg/kg]
280   REAL,      INTENT(IN),       DIMENSION(klon)    :: cldfra              !--cloud fraction in gridbox                     [-]
281   REAL,      INTENT(IN),       DIMENSION(klon)    :: tke                 !--turbulent kinetic energy                      [m2/s2]
282   REAL,      INTENT(IN),       DIMENSION(klon)    :: tke_dissip          !--TKE dissipation                               [m2/s3]
283
284   REAL,      INTENT(IN),       DIMENSION(klon)    :: qice_ini            !--initial specific ice content gridbox-mean     [kg/kg]
285   REAL,      INTENT(IN),       DIMENSION(klon)    :: snowcld             !--in-cloud snowfall flux                        [kg/m2/s]
286   REAL,      INTENT(IN),       DIMENSION(klon)    :: snowfracld          !--cloudy precip fraction                        [-]
287   REAL,      INTENT(IN),       DIMENSION(klon)    :: sursat_e            !--environment supersaturation                   [-]
288   REAL,      INTENT(IN),       DIMENSION(klon)    :: invtau_e            !--inverse time-scale of mixing with environment [s-1]
289   REAL,      INTENT(OUT),      DIMENSION(klon)    :: qliq                !--specific liquid content gridbox-mean          [kg/kg]
290   REAL,      INTENT(OUT),      DIMENSION(klon)    :: qvap_cld            !--specific cloud vapor content, gridbox-mean    [kg/kg]
291   REAL,      INTENT(OUT),      DIMENSION(klon)    :: qice                !--specific ice content gridbox-mean             [kg/kg]
292
293   REAL,      INTENT(INOUT),    DIMENSION(klon)    :: icefrac             !--fraction of ice in condensed water            [-]
294   REAL,      INTENT(INOUT),    DIMENSION(klon)    :: dicefracdT
295
296   REAL,      INTENT(OUT),      DIMENSION(klon)    :: cldfraliq           !--fraction of cldfra where liquid               [-]
297   REAL,      INTENT(OUT),      DIMENSION(klon)    :: sigma2_icefracturb  !--Sigma2 of the ice supersaturation PDF         [-]
298   REAL,      INTENT(OUT),      DIMENSION(klon)    :: mean_icefracturb    !--Mean of the ice supersaturation PDF           [-]
299
300   REAL, DIMENSION(klon) :: qzero, qsatl, dqsatl, qsati, dqsati           !--specific humidity saturation values
301   INTEGER :: i
302
303   REAL :: qvap_incl, qice_incl, qliq_incl, qiceini_incl                  !--In-cloud specific quantities                  [kg/kg]
304   REAL :: water_vapor_diff                                               !--Water-vapour diffusion coeff in air (f(T,P))  [m2/s]
305   REAL :: air_thermal_conduct                                            !--Thermal conductivity of air (f(T))            [J/m/K/s]
306   REAL :: C0                                                             !--Lagrangian structure function                 [-]
307   REAL :: tau_dissipturb
308   REAL :: invtau_phaserelax
309   REAL :: sigma2_pdf
310   REAL :: ai, bi, B0
311   REAL :: sursat_iceliq
312   REAL :: sursat_equ
313   REAL :: liqfra_max
314   REAL :: sursat_iceext
315   REAL :: nb_crystals                                                    !--number concentration of ice crystals          [#/m3]
316   REAL :: moment1_PSD                                                    !--1st moment of ice PSD
317   REAL :: N0_PSD, lambda_PSD                                             !--parameters of the exponential PSD
318
319   REAL :: cldfra1D
320   REAL :: rho_air
321   REAL :: psati                                                          !--saturation vapor pressure wrt ice             [Pa]
322
323                                                                       
324    REAL :: tempvig1, tempvig2
325
326   tempvig1    = -21.06 + RTT
327   tempvig2    = -30.35 + RTT
328   C0            = 10.                                                    !--value assumed in Field2014           
329   sursat_iceext = -0.1
330   qzero(:)      = 0.
331   cldfraliq(:)  = 0.
332   qliq(:)       = 0.
333   qice(:)       = 0.
334   qvap_cld(:)   = 0.
335   sigma2_icefracturb(:) = 0.
336   mean_icefracturb(:)   = 0.
337
338   !--wrt liquid
339   CALL calc_qsat_ecmwf(klon,temp(:),qzero(:),pplay(:),RTT,1,.false.,qsatl(:),dqsatl(:))
340   !--wrt ice
341   CALL calc_qsat_ecmwf(klon,temp(:),qzero(:),pplay(:),RTT,2,.false.,qsati(:),dqsati(:))
342
343
344    DO i=1,klon
345     rho_air  = pplay(i) / temp(i) / RD
346     ! because cldfra is intent in, but can be locally modified due to test
347     cldfra1D = cldfra(i)
348     ! activate param for concerned grid points and for cloudy conditions
349     IF ((pticefracturb(i)) .AND. (cldfra(i) .GT. 0.)) THEN
350        IF (cldfra(i) .GE. 1.0) THEN
351           cldfra1D = 1.0
352        END IF
353       
354        ! T>0°C, no ice allowed
355        IF ( temp(i) .GE. RTT ) THEN
356           qvap_cld(i)   = qsatl(i) * cldfra1D
357           qliq(i)       = MAX(0.0,qtot_incl(i)-qsatl(i))  * cldfra1D
358           qice(i)       = 0.
359           cldfraliq(i)  = 1.
360           icefrac(i)    = 0.
361           dicefracdT(i) = 0.
362       
363        ! T<-38°C, no liquid allowed
364        ELSE IF ( temp(i) .LE. temp_nowater) THEN
365           qvap_cld(i)   = qsati(i) * cldfra1D
366           qliq(i)       = 0.
367           qice(i)       = MAX(0.0,qtot_incl(i)-qsati(i)) * cldfra1D
368           cldfraliq(i)  = 0.
369           icefrac(i)    = 1.
370           dicefracdT(i) = 0.
371
372
373        !---------------------------------------------------------
374        !--             MIXED PHASE TEMPERATURE REGIME         
375        !---------------------------------------------------------
376        !--In the mixed phase regime (-38°C< T <0°C) we distinguish
377        !--3 possible subcases.
378        !--1.  No pre-existing ice 
379        !--2A. Pre-existing ice and no turbulence
380        !--2B. Pre-existing ice and turbulence
381        ELSE
382
383           ! gamma_snwretro controls the contribution of snowflakes to the negative feedback
384           ! note that for reasons related to inetarctions with the condensation iteration in lscp_main
385           ! we consider here the mean snowflake concentration in the mesh (not the in-cloud concentration)
386           ! when poprecip is active, it will be worth testing considering the incloud fraction, dividing
387           ! by snowfracld     
388           ! qiceini_incl  = qice_ini(i) / cldfra1D + &
389           !              gamma_snwretro * snowcld(i) * RG * dtime / ( paprsdn(i) - paprsup(i) )
390           ! assuming constant snowfall velocity
391           qiceini_incl  = qice_ini(i) / cldfra1D + gamma_snwretro * snowcld(i) / pplay(i) * RD * temp(i) / snow_fallspeed
392
393           !--1. No preexisting ice and no mixing with environment: if vertical motion, fully liquid
394           !--cloud else fully iced cloud
395           IF ( (qiceini_incl .LT. eps) .AND. (invtau_e(i) .LT. eps) ) THEN
396              IF ( (wvel(i) .GT. eps) .OR. (tke(i) .GT. eps) ) THEN
397                 qvap_cld(i)   = qsatl(i) * cldfra1D
398                 qliq(i)       = MAX(0.,qtot_incl(i)-qsatl(i)) * cldfra1D
399                 qice(i)       = 0.
400                 cldfraliq(i)  = 1.
401                 icefrac(i)    = 0.
402                 dicefracdT(i) = 0.
403              ELSE
404                 qvap_cld(i)   = qsati(i) * cldfra1D
405                 qliq(i)       = 0.
406                 qice(i)       = MAX(0.,qtot_incl(i)-qsati(i)) * cldfra1D
407                 cldfraliq(i)  = 0.
408                 icefrac(i)    = 1.
409                 dicefracdT(i) = 0.
410              ENDIF
411           
412
413           !--2. Pre-existing ice and/or mixing with environment:computation of ice properties for
414           !--feedback
415           ELSE
416
417              sursat_iceliq = qsatl(i)/qsati(i) - 1.
418              psati         = qsati(i) * pplay(i) / (RD/RV)
419             
420              !--We assume an exponential ice PSD whose parameters
421              !--are computed following Morrison&Gettelman 2008
422              !--Ice number density is assumed equals to INP density
423              !--which is for naero5>0 a function of temperature (DeMott 2010)   
424              !--bi and B0 are microphysical function characterizing
425              !--vapor/ice interactions
426              !--tau_phase_relax is the typical time of vapor deposition
427              !--onto ice crystals
428
429              !--For naero5<=0 INP density is derived from the empirical fit
430              !--from MARCUS campaign from Vignon 2021
431              !--/!\ Note that option is very specific and should be use for
432              !--the Southern Ocean and the Antarctic
433
434              IF (naero5 .LE. 0) THEN
435                 IF ( temp(i) .GT. tempvig1 ) THEN
436                      nb_crystals = 1.e3 * 10**(-0.14*(temp(i)-tempvig1) - 2.88)
437                 ELSE IF ( temp(i) .GT. tempvig2 ) THEN
438                      nb_crystals = 1.e3 * 10**(-0.31*(temp(i)-tempvig1) - 2.88)
439                 ELSE
440                      nb_crystals = 1.e3 * 10**(0.)
441                 ENDIF
442              ELSE
443                 nb_crystals = 1.e3 * 5.94e-5 * ( RTT - temp(i) )**3.33 * naero5**(0.0264*(RTT-temp(i))+0.0033)
444              ENDIF
445              lambda_PSD  = ( (RPI*rho_ice*nb_crystals) / (rho_air * MAX(qiceini_incl , eps) ) ) ** (1./3.)
446              N0_PSD      = nb_crystals * lambda_PSD
447              moment1_PSD = N0_PSD/lambda_PSD**2
448
449              !--Formulae for air thermal conductivity and water vapor diffusivity
450              !--comes respectively from Beard and Pruppacher (1971)
451              !--and  Hall and Pruppacher (1976)
452
453              air_thermal_conduct = ( 5.69 + 0.017 * ( temp(i) - RTT ) ) * 1.e-3 * 4.184
454              water_vapor_diff    = 2.11*1e-5 * ( temp(i) / RTT )**1.94 * ( 101325 / pplay(i) )
455             
456              bi = 1./((qsati(i)+qsatl(i))/2.) + RLSTT**2 / RCPD / RV / temp(i)**2
457              B0 = 4. * RPI * capa_crystal * 1. / (  RLSTT**2 / air_thermal_conduct / RV / temp(i)**2  &
458                                                  +  RV * temp(i) / psati / water_vapor_diff  )
459              invtau_phaserelax = bi * B0 * moment1_PSD
460             
461              ai = RG / RD / temp(i) * ( RD * RLSTT / RCPD / RV / temp(i) - 1. )
462              sursat_equ    = (ai * wvel(i) + sursat_e(i)*invtau_e(i)) / (invtau_phaserelax + invtau_e(i))
463              ! as sursaturation is by definition lower than -1 and
464              ! because local supersaturation > 1 are never found in the atmosphere
465
466              !--2A. No TKE : stationnary binary solution depending on vertical velocity and mixing with env.
467              ! If Sequ > Siw liquid cloud, else ice cloud
468              IF ( tke_dissip(i) .LE. eps )  THEN
469                 sigma2_icefracturb(i)= 0.
470                 mean_icefracturb(i)  = sursat_equ
471                 IF (sursat_equ .GT. sursat_iceliq) THEN
472                    qvap_cld(i)   = qsatl(i) * cldfra1D
473                    qliq(i)       = MAX(0.,qtot_incl(i)-qsatl(i)) * cldfra1D
474                    qice(i)       = 0.
475                    cldfraliq(i)  = 1.
476                    icefrac(i)    = 0.
477                    dicefracdT(i) = 0.
478                 ELSE
479                    qvap_cld(i)   = qsati(i) * cldfra1D
480                    qliq(i)       = 0.
481                    qice(i)       = MAX(0.,qtot_incl(i)-qsati(i)) * cldfra1D
482                    cldfraliq(i)  = 0.
483                    icefrac(i)    = 1.
484                    dicefracdT(i) = 0.
485                 ENDIF
486                 
487              !--2B. TKE and ice : ice supersaturation PDF
488              !--we compute the cloud liquid properties with a Gaussian PDF
489              !--of ice supersaturation F(Si) (Field2014, Furtado2016).
490              !--Parameters of the PDF are function of turbulence and
491              !--microphysics/existing ice.
492              ELSE 
493                     
494                 !--Tau_dissipturb is the time needed for turbulence to decay
495                 !--due to viscosity
496                 tau_dissipturb = gamma_taud * 2. * 2./3. * tke(i) / tke_dissip(i) / C0
497
498                 !--------------------- PDF COMPUTATIONS ---------------------
499                 !--Formulae for sigma2_pdf (variance), mean of PDF in Raillard2025
500                 !--cloud liquid fraction and in-cloud liquid content are given
501                 !--by integrating resp. F(Si) and Si*F(Si)
502                 !--Liquid is limited by the available water vapor trough a
503                 !--maximal liquid fraction
504                 !--qice_ini(i) / cldfra1D = qiceincld without precip
505
506                 liqfra_max = MAX(0., (MIN (1.,( qtot_incl(i) - (qice_ini(i) / cldfra1D) - qsati(i) * (1 + sursat_iceext ) ) / ( qsatl(i) - qsati(i) ) ) ) )
507                 sigma2_pdf = 1./2. * ( ai**2 ) *  2./3. * tke(i) * tau_dissipturb / (invtau_phaserelax + invtau_e(i))
508                 ! sursat ranges between -1 and 1, so we prevent sigma2 so exceed 1
509                 cldfraliq(i) = 0.5 * (1. - erf( ( sursat_iceliq - sursat_equ) / (SQRT(2.* sigma2_pdf) ) ) )
510                 IF (cldfraliq(i) .GT. liqfra_max) THEN
511                     cldfraliq(i) = liqfra_max
512                 ENDIF
513                 
514                 qliq_incl = qsati(i) * SQRT(sigma2_pdf) / SQRT(2.*RPI) * EXP( -1.*(sursat_iceliq - sursat_equ)**2. / (2.*sigma2_pdf) )  &
515                           - qsati(i) * cldfraliq(i) * (sursat_iceliq - sursat_equ )
516                 
517                 sigma2_icefracturb(i)= sigma2_pdf
518                 mean_icefracturb(i)  = sursat_equ
519     
520                 !------------ SPECIFIC VAPOR CONTENT AND WATER CONSERVATION  ------------
521
522                 IF ( (qliq_incl .LE. eps) .OR. (cldfraliq(i) .LE. eps) ) THEN
523                     qliq_incl    = 0.
524                     cldfraliq(i) = 0.
525                 END IF
526                 
527                 !--Specific humidity is the max between qsati and the weighted mean between
528                 !--qv in MPC patches and qv in ice-only parts. We assume that MPC parts are
529                 !--always at qsatl and ice-only parts slightly subsaturated (qsati*sursat_iceext+1)
530                 !--The whole cloud can therefore be supersaturated but never subsaturated.
531
532                 qvap_incl = MAX(qsati(i), ( 1. - cldfraliq(i) ) * (sursat_iceext + 1.) * qsati(i) + cldfraliq(i) * qsatl(i) )
533
534                 IF ( qvap_incl  .GE. qtot_incl(i) ) THEN
535                    qvap_incl = qsati(i)
536                    qliq_incl = MAX(0.0,qtot_incl(i) - qvap_incl)
537                    qice_incl = 0.
538
539                 ELSEIF ( (qvap_incl + qliq_incl) .GE. qtot_incl(i) ) THEN
540                    qliq_incl = MAX(0.0,qtot_incl(i) - qvap_incl)
541                    qice_incl = 0.
542                 ELSE
543                    qice_incl = qtot_incl(i) - qvap_incl - qliq_incl
544                 END IF
545
546                 qvap_cld(i)   = qvap_incl * cldfra1D
547                 qliq(i)       = qliq_incl * cldfra1D
548                 qice(i)       = qice_incl * cldfra1D
549                 IF ((qice(i)+qliq(i)) .GT. 0.) THEN
550                    icefrac(i)    = qice(i) / ( qice(i) + qliq(i) )
551                 ELSE
552                    icefrac(i)    = 1. ! to keep computation of qsat wrt ice in condensation loop in lmdz_lscp_main
553                 ENDIF
554                 dicefracdT(i) = 0.
555
556              END IF ! Enough TKE
557           
558           END IF ! End qini
559
560        END IF ! ! MPC temperature
561
562     END IF ! pticefracturb and cldfra
563   
564   ENDDO ! klon
565END SUBROUTINE ICEFRAC_LSCP_TURB
566!
567!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
568
569
570SUBROUTINE CALC_QSAT_ECMWF(klon,temp,qtot,pressure,tref,phase,flagth,qs,dqs)
571!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
572    ! Calculate qsat following ECMWF method
573!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
574
575
576USE yoethf_mod_h
577        USE yomcst_mod_h
578IMPLICIT NONE
579
580
581    include "FCTTRE.h"
582
583    INTEGER, INTENT(IN) :: klon  ! number of horizontal grid points
584    REAL, INTENT(IN), DIMENSION(klon) :: temp     ! temperature in K
585    REAL, INTENT(IN), DIMENSION(klon) :: qtot     ! total specific water in kg/kg
586    REAL, INTENT(IN), DIMENSION(klon) :: pressure ! pressure in Pa
587    REAL, INTENT(IN)                  :: tref     ! reference temperature in K
588    LOGICAL, INTENT(IN) :: flagth     ! flag for qsat calculation for thermals
589    INTEGER, INTENT(IN) :: phase
590    ! phase: 0=depend on temperature sign (temp>tref -> liquid, temp<tref, solid)
591    !        1=liquid
592    !        2=solid
593
594    REAL, INTENT(OUT), DIMENSION(klon) :: qs      ! saturation specific humidity [kg/kg]
595    REAL, INTENT(OUT), DIMENSION(klon) :: dqs     ! derivation of saturation specific humidity wrt T
596
597    REAL delta, cor, cvm5
598    INTEGER i
599
600    DO i=1,klon
601
602    IF (phase .EQ. 1) THEN
603        delta=0.
604    ELSEIF (phase .EQ. 2) THEN
605        delta=1.
606    ELSE
607        delta=MAX(0.,SIGN(1.,tref-temp(i)))
608    ENDIF
609
610    IF (flagth) THEN
611    cvm5=R5LES*(1.-delta) + R5IES*delta
612    ELSE
613    cvm5 = R5LES*RLVTT*(1.-delta) + R5IES*RLSTT*delta
614    cvm5 = cvm5 /RCPD/(1.0+RVTMP2*(qtot(i)))
615    ENDIF
616
617    qs(i)= R2ES*FOEEW(temp(i),delta)/pressure(i)
618    qs(i)=MIN(0.5,qs(i))
619    cor=1./(1.-RETV*qs(i))
620    qs(i)=qs(i)*cor
621    dqs(i)= FOEDE(temp(i),delta,cvm5,qs(i),cor)
622
623    END DO
624
625END SUBROUTINE CALC_QSAT_ECMWF
626!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
627
628
629!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
630SUBROUTINE CALC_GAMMASAT(klon,temp,qtot,pressure,gammasat,dgammasatdt)
631
632!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
633    ! programme that calculates the gammasat parameter that determines the
634    ! homogeneous condensation thresholds for cold (<0oC) clouds
635    ! condensation at q>gammasat*qsat
636    ! Etienne Vignon, March 2021
637!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
638
639    use lmdz_lscp_ini, only: iflag_gammasat, temp_nowater, RTT
640    use lmdz_lscp_ini, only: a_homofreez, b_homofreez, delta_hetfreez
641
642    IMPLICIT NONE
643
644
645    INTEGER, INTENT(IN) :: klon                       ! number of horizontal grid points
646    REAL, INTENT(IN), DIMENSION(klon) :: temp         ! temperature in K
647    REAL, INTENT(IN), DIMENSION(klon) :: qtot         ! total specific water in kg/kg
648
649    REAL, INTENT(IN), DIMENSION(klon) :: pressure     ! pressure in Pa
650
651    REAL, INTENT(OUT), DIMENSION(klon) :: gammasat    ! coefficient to multiply qsat with to calculate saturation
652    REAL, INTENT(OUT), DIMENSION(klon) :: dgammasatdt ! derivative of gammasat wrt temperature
653
654    REAL, DIMENSION(klon) ::  qsi,qsl,dqsl,dqsi
655    REAL  f_homofreez, fac
656
657    INTEGER i
658   
659        CALL CALC_QSAT_ECMWF(klon,temp,qtot,pressure,RTT,1,.false.,qsl,dqsl)
660        CALL CALC_QSAT_ECMWF(klon,temp,qtot,pressure,RTT,2,.false.,qsi,dqsi)
661
662    DO i = 1, klon
663
664        IF ( temp(i) .GE. RTT ) THEN
665            ! warm clouds: condensation at saturation wrt liquid
666            gammasat(i) = 1.
667            dgammasatdt(i) = 0.
668
669        ELSE
670            ! cold clouds: qsi > qsl
671           
672            ! homogeneous freezing of aerosols, according to
673            ! Koop, 2000 and Ren and MacKenzie, 2005 (QJRMS)
674            ! 'Cirrus regime'
675            ! if f_homofreez > qsl / qsi, liquid nucleation
676            ! if f_homofreez < qsl / qsi, homogeneous freezing of aerosols
677            ! Note: f_homofreez = qsl / qsi for temp ~= -38degC
678            f_homofreez = a_homofreez - temp(i) / b_homofreez
679           
680            IF ( iflag_gammasat .GE. 3 ) THEN
681              ! condensation at homogeneous freezing threshold for temp < -38 degC
682              ! condensation at liquid saturation for temp > -38 degC
683              IF ( f_homofreez .LE. qsl(i) / qsi(i) ) THEN
684                gammasat(i) = f_homofreez
685                dgammasatdt(i) = - 1. / b_homofreez
686              ELSE
687                gammasat(i) = qsl(i) / qsi(i)
688                dgammasatdt(i) = ( dqsl(i) * qsi(i) - dqsi(i) * qsl(i) ) / qsi(i) / qsi(i)
689              ENDIF
690
691            ELSEIF ( iflag_gammasat .EQ. 2 ) THEN
692              ! condensation at homogeneous freezing threshold for temp < -38 degC
693              ! condensation at a threshold linearly decreasing between homogeneous
694              ! freezing and ice saturation for -38 degC < temp < temp_nowater
695              ! condensation at ice saturation for temp > temp_nowater
696              ! If temp_nowater = 235.15 K, this is equivalent to iflag_gammasat = 1
697              IF ( f_homofreez .LE. qsl(i) / qsi(i) ) THEN
698                gammasat(i) = f_homofreez
699                dgammasatdt(i) = - 1. / b_homofreez
700              ELSEIF ( temp(i) .LE. temp_nowater ) THEN
701                ! Here, we assume that f_homofreez = qsl / qsi for temp = -38 degC = 235.15 K
702                dgammasatdt(i) = ( a_homofreez - 235.15 / b_homofreez - 1. ) &
703                               / ( 235.15 - temp_nowater )
704                gammasat(i) = dgammasatdt(i) * ( temp(i) - temp_nowater ) + 1.
705              ELSE
706                gammasat(i) = 1.
707                dgammasatdt(i) = 0.
708              ENDIF
709
710            ELSEIF ( iflag_gammasat .EQ. 1 ) THEN
711              ! condensation at homogeneous freezing threshold for temp < -38 degC
712              ! condensation at ice saturation for temp > -38 degC
713              IF ( f_homofreez .LE. qsl(i) / qsi(i) ) THEN
714                gammasat(i) = f_homofreez
715                dgammasatdt(i) = - 1. / b_homofreez
716              ELSE
717                gammasat(i) = 1.
718                dgammasatdt(i) = 0.
719              ENDIF
720
721            ELSE
722              ! condensation at ice saturation for temp < -38 degC
723              ! condensation at ice saturation for temp > -38 degC
724              gammasat(i) = 1.
725              dgammasatdt(i) = 0.
726
727            ENDIF
728
729            ! Note that the delta_hetfreez parameter allows to linearly decrease the
730            ! condensation threshold between the calculated threshold and the ice saturation
731            ! for delta_hetfreez = 1, the threshold is the calculated condensation threshold
732            ! for delta_hetfreez = 0, the threshold is the ice saturation
733            gammasat(i) = ( 1. - delta_hetfreez ) + delta_hetfreez * gammasat(i)
734            dgammasatdt(i) = delta_hetfreez * dgammasatdt(i)
735
736        ENDIF
737   
738    END DO
739
740
741END SUBROUTINE CALC_GAMMASAT
742!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
743
744
745!++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
746SUBROUTINE DISTANCE_TO_CLOUD_TOP(klon,klev,k,temp,pplay,paprs,rneb,distcltop1D,temp_cltop)
747!++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
748   
749   USE lmdz_lscp_ini, ONLY : rd,rg,tresh_cl
750
751   IMPLICIT NONE
752   
753   INTEGER, INTENT(IN) :: klon,klev                !number of horizontal and vertical grid points
754   INTEGER, INTENT(IN) :: k                        ! vertical index
755   REAL, INTENT(IN), DIMENSION(klon,klev) :: temp  ! temperature in K
756   REAL, INTENT(IN), DIMENSION(klon,klev) :: pplay ! pressure middle layer in Pa
757   REAL, INTENT(IN), DIMENSION(klon,klev+1) :: paprs ! pressure interfaces in Pa
758   REAL, INTENT(IN), DIMENSION(klon,klev) :: rneb  ! cloud fraction
759
760   REAL, INTENT(OUT), DIMENSION(klon) :: distcltop1D  ! distance from cloud top
761   REAL, INTENT(OUT), DIMENSION(klon) :: temp_cltop     ! temperature of cloud top
762   
763   REAL dzlay(klon,klev)
764   REAL zlay(klon,klev)
765   REAL dzinterf
766   INTEGER i,k_top, kvert
767   LOGICAL bool_cl
768
769
770   DO i=1,klon
771         ! Initialization height middle of first layer
772          dzlay(i,1) = Rd * temp(i,1) / rg * log(paprs(i,1)/paprs(i,2))
773          zlay(i,1) = dzlay(i,1)/2
774
775          DO kvert=2,klev
776                 IF (kvert.EQ.klev) THEN
777                       dzlay(i,kvert) = 2*(rd * temp(i,kvert) / rg * log(paprs(i,kvert)/pplay(i,kvert)))
778                 ELSE
779                       dzlay(i,kvert) = rd * temp(i,kvert) / rg * log(paprs(i,kvert)/paprs(i,kvert+1))
780                 ENDIF
781                       dzinterf       = rd * temp(i,kvert) / rg * log(pplay(i,kvert-1)/pplay(i,kvert))
782                       zlay(i,kvert)  = zlay(i,kvert-1) + dzinterf
783           ENDDO
784   ENDDO
785   
786   DO i=1,klon
787          k_top = k
788          IF (rneb(i,k) .LE. tresh_cl) THEN
789                 bool_cl = .FALSE.
790          ELSE
791                 bool_cl = .TRUE.
792          ENDIF
793
794          DO WHILE ((bool_cl) .AND. (k_top .LE. klev))
795          ! find cloud top
796                IF (rneb(i,k_top) .GT. tresh_cl) THEN
797                      k_top = k_top + 1
798                ELSE
799                      bool_cl = .FALSE.
800                      k_top   = k_top - 1
801                ENDIF
802          ENDDO
803          k_top=min(k_top,klev)
804
805          !dist to top is dist between current layer and layer of cloud top (from middle to middle) + dist middle to
806          !interf for layer of cloud top
807          distcltop1D(i) = zlay(i,k_top) - zlay(i,k) + dzlay(i,k_top)/2
808          temp_cltop(i)  = temp(i,k_top)
809   ENDDO ! klon
810
811END SUBROUTINE DISTANCE_TO_CLOUD_TOP
812!++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
813
814!++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
815FUNCTION GAMMAINC ( p, x )
816
817!*****************************************************************************80
818!
819!! GAMMAINC computes the regularized lower incomplete Gamma Integral
820!
821!  Modified:
822!
823!    20 January 2008
824!
825!  Author:
826!
827!    Original FORTRAN77 version by B Shea.
828!    FORTRAN90 version by John Burkardt.
829!
830!  Reference:
831!
832!    B Shea,
833!    Algorithm AS 239:
834!    Chi-squared and Incomplete Gamma Integral,
835!    Applied Statistics,
836!    Volume 37, Number 3, 1988, pages 466-473.
837!
838!  Parameters:
839!
840!    Input, real X, P, the parameters of the incomplete
841!    gamma ratio.  0 <= X, and 0 < P.
842!
843!    Output, real GAMMAINC, the value of the incomplete
844!    Gamma integral.
845!
846  IMPLICIT NONE
847
848  REAL A
849  REAL AN
850  REAL ARG
851  REAL B
852  REAL C
853  REAL, PARAMETER :: ELIMIT = - 88.0E+00
854  REAL GAMMAINC
855  REAL, PARAMETER :: OFLO = 1.0E+37
856  REAL P
857  REAL, PARAMETER :: PLIMIT = 1000.0E+00
858  REAL PN1
859  REAL PN2
860  REAL PN3
861  REAL PN4
862  REAL PN5
863  REAL PN6
864  REAL RN
865  REAL, PARAMETER :: TOL = 1.0E-14
866  REAL X
867  REAL, PARAMETER :: XBIG = 1.0E+08
868
869  GAMMAINC = 0.0E+00
870
871  IF ( X == 0.0E+00 ) THEN
872    GAMMAINC = 0.0E+00
873    RETURN
874  END IF
875!
876!  IF P IS LARGE, USE A NORMAL APPROXIMATION.
877!
878  IF ( PLIMIT < P ) THEN
879
880    PN1 = 3.0E+00 * SQRT ( P ) * ( ( X / P )**( 1.0E+00 / 3.0E+00 ) &
881    + 1.0E+00 / ( 9.0E+00 * P ) - 1.0E+00 )
882
883    GAMMAINC = 0.5E+00 * ( 1. + ERF ( PN1 ) )
884    RETURN
885
886  END IF
887!
888!  IF X IS LARGE SET GAMMAD = 1.
889!
890  IF ( XBIG < X ) THEN
891    GAMMAINC = 1.0E+00
892    RETURN
893  END IF
894!
895!  USE PEARSON'S SERIES EXPANSION.
896!  (NOTE THAT P IS NOT LARGE ENOUGH TO FORCE OVERFLOW IN ALOGAM).
897!
898  IF ( X <= 1.0E+00 .OR. X < P ) THEN
899
900    ARG = P * LOG ( X ) - X - LOG_GAMMA ( P + 1.0E+00 )
901    C = 1.0E+00
902    GAMMAINC = 1.0E+00
903    A = P
904
905    DO
906
907      A = A + 1.0E+00
908      C = C * X / A
909      GAMMAINC = GAMMAINC + C
910
911      IF ( C <= TOL ) THEN
912        EXIT
913      END IF
914
915    END DO
916
917    ARG = ARG + LOG ( GAMMAINC )
918
919    IF ( ELIMIT <= ARG ) THEN
920      GAMMAINC = EXP ( ARG )
921    ELSE
922      GAMMAINC = 0.0E+00
923    END IF
924!
925!  USE A CONTINUED FRACTION EXPANSION.
926!
927  ELSE
928
929    ARG = P * LOG ( X ) - X - LOG_GAMMA ( P )
930    A = 1.0E+00 - P
931    B = A + X + 1.0E+00
932    C = 0.0E+00
933    PN1 = 1.0E+00
934    PN2 = X
935    PN3 = X + 1.0E+00
936    PN4 = X * B
937    GAMMAINC = PN3 / PN4
938
939    DO
940
941      A = A + 1.0E+00
942      B = B + 2.0E+00
943      C = C + 1.0E+00
944      AN = A * C
945      PN5 = B * PN3 - AN * PN1
946      PN6 = B * PN4 - AN * PN2
947
948      IF ( PN6 /= 0.0E+00 ) THEN
949
950        RN = PN5 / PN6
951
952        IF ( ABS ( GAMMAINC - RN ) <= MIN ( TOL, TOL * RN ) ) THEN
953          EXIT
954        END IF
955
956        GAMMAINC = RN
957
958      END IF
959
960      PN1 = PN3
961      PN2 = PN4
962      PN3 = PN5
963      PN4 = PN6
964!
965!  RE-SCALE TERMS IN CONTINUED FRACTION IF TERMS ARE LARGE.
966!
967      IF ( OFLO <= ABS ( PN5 ) ) THEN
968        PN1 = PN1 / OFLO
969        PN2 = PN2 / OFLO
970        PN3 = PN3 / OFLO
971        PN4 = PN4 / OFLO
972      END IF
973
974    END DO
975
976    ARG = ARG + LOG ( GAMMAINC )
977
978    IF ( ELIMIT <= ARG ) THEN
979      GAMMAINC = 1.0E+00 - EXP ( ARG )
980    ELSE
981      GAMMAINC = 1.0E+00
982    END IF
983
984  END IF
985
986  RETURN
987END FUNCTION GAMMAINC
988!++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
989
990END MODULE lmdz_lscp_tools
991
992
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