source: LMDZ6/trunk/libf/phylmd/ocean_albedo.F90 @ 3513

Last change on this file since 3513 was 2740, checked in by lguez, 8 years ago

Added output of nudging coefficients for temperature and humidity,
along those for the wind.
File size: 10.1 KB
Line 
1!
2! $Id$
3!
4
5SUBROUTINE ocean_albedo(knon,zrmu0,knindex,pwind,SFRWL,alb_dir_new,alb_dif_new)
6!!
7!!****  *ALBEDO_RS14* 
8!!
9!!    PURPOSE
10!!    -------
11!!     computes the direct & diffuse albedo over open water
12!!     
13!!**  METHOD
14!!    ------
15!!
16!!    EXTERNAL
17!!    --------
18!!
19!!    IMPLICIT ARGUMENTS
20!!    ------------------
21!!     
22!!    REFERENCE
23!!    ---------
24!!     
25!!    AUTHOR
26!!    ------
27!!      R. Séférian           * Meteo-France *
28!!
29!!    MODIFICATIONS
30!!    -------------
31!!      Original    03/2014
32!!                  05/2014 R. Séférian & B. Decharme :: Adaptation to spectral
33!!                  computation for diffuse and direct albedo
34!!                  08/2014 S. Baek :: for wider wavelength range 200-4000nm and
35!!                  adaptation to LMDZ + whitecap effect by Koepke + chrolophyll
36!!                  map from climatology file
37!!                  10/2016 O. Boucher :: some optimisation following R.
38!!                  Seferian's work in the CNRM Model
39!!       
40!-------------------------------------------------------------------------------
41!
42!*           DECLARATIONS
43!            ------------
44!
45USE ocean_albedo_para
46USE dimphy
47USE phys_state_var_mod, ONLY : chl_con
48!
49!
50IMPLICIT NONE
51!
52!*      0.1    declarations of arguments
53!              -------------------------
54!
55include "clesphys.h"
56!
57INTEGER, INTENT(IN) :: knon
58INTEGER, DIMENSION(klon), INTENT(IN) :: knindex
59REAL, DIMENSION(klon), INTENT(IN) :: zrmu0         !--cos(SZA) on full vector
60REAL, DIMENSION(klon), INTENT(IN) :: pwind         !--wind speed on compressed vector
61REAL, DIMENSION(6),INTENT(IN) :: SFRWL
62REAL, DIMENSION(klon,nsw), INTENT(OUT) :: alb_dir_new, alb_dif_new
63!
64!*      0.2    declarations of local variables
65!              -------------------------
66!
67REAL, DIMENSION(klon)           :: ZCHL        ! surface chlorophyll
68REAL, DIMENSION(klon)           :: ZCOSZEN     ! Cosine of the zenith solar angle
69!
70INTEGER                         :: JWL, INU    ! indexes
71INTEGER                         :: JI
72REAL                            :: ZWL         ! input parameter: wavelength and diffuse/direct fraction of light
73REAL:: ZCHLABS, ZAW, ZBW, ZREFM, ZYLMD, ZUE, ZUE2 ! scalar computation variables
74!
75REAL, DIMENSION(klon) :: ZAP, ZXX2, ZR00, ZRR0, ZRRR               ! computation variables
76REAL, DIMENSION(klon) :: ZR22, ZR11DF                              ! computation variables
77REAL, DIMENSION(klon) :: ZBBP, ZNU, ZHB                            ! computation variables
78REAL, DIMENSION(klon) :: ZR11, ZRW, ZRWDF, ZRDF                    ! 4 components of the OSA
79REAL, DIMENSION(klon) :: ZSIG, ZFWC, ZWORK1, ZWORK2, ZWORK3
80!
81!--initialisations-------------
82!
83
84IF (knon==0) RETURN ! A verifier pourquoi on en a besoin...
85
86alb_dir_new(:,:) = 0.
87alb_dif_new(:,:) = 0.
88!
89! Initialisation of chlorophyll content
90! ZCHL(:) = CHL_CON!0.05 ! averaged global values for surface chlorophyll
91IF (ok_chlorophyll) THEN
92  ZCHL(1:knon)=CHL_CON(knindex(1:knon))
93ELSE
94  ZCHL(1:knon) = 0.05
95ENDIF
96
97! variables that do not depend on wavelengths
98! loop over the grid points
99! functions of chlorophyll content
100ZWORK1(1:knon)= EXP(LOG(ZCHL(1:knon))*0.65)
101ZWORK2(1:knon)= 0.416 * EXP(LOG(ZCHL(1:knon))*0.766)
102ZWORK3(1:knon)= LOG10(ZCHL(1:knon))
103! store the cosine of the solar zenith angle
104ZCOSZEN(1:knon) = zrmu0(knindex(1:knon))
105! Compute sigma derived from wind speed (Cox & Munk reflectance model)
106ZSIG(1:knon)=SQRT(0.003+0.00512*PWIND(1:knon))
107! original : correction for foam (Eq 16-17)
108! has to be update once we have information from wave model (discussion with G. Madec)
109ZFWC(1:knon)=3.97e-4*PWIND(1:knon)**1.59 ! Salisbury 2014 eq(2) at 37GHz, value in fraction
110!
111DO JWL=1,NNWL           ! loop over the wavelengths
112  !
113  !---------------------------------------------------------------------------------
114  ! 0- Compute baseline values
115  !---------------------------------------------------------------------------------
116   
117  ! Get refractive index for the correspoding wavelength
118  ZWL=XAKWL(JWL)      !!!--------- wavelength value
119  ZREFM= XAKREFM(JWL) !!!--------- refraction index value
120 
121  !---------------------------------------------------------------------------------
122  ! 1- Compute direct surface albedo (ZR11)
123  !---------------------------------------------------------------------------------
124  !
125  ZXX2(1:knon)=SQRT(1.0-(1.0-ZCOSZEN(1:knon)**2)/ZREFM**2)
126  ZRR0(1:knon)=0.50*(((ZXX2(1:knon)-ZREFM*ZCOSZEN(1:knon))/(ZXX2(1:knon)+ZREFM*ZCOSZEN(1:knon)))**2 +  &
127               ((ZCOSZEN(1:knon)-ZREFM*ZXX2(1:knon))/(ZCOSZEN(1:knon)+ZREFM*ZXX2(1:knon)))**2)
128  ZRRR(1:knon)=0.50*(((ZXX2(1:knon)-1.34*ZCOSZEN(1:knon))/(ZXX2(1:knon)+1.34*ZCOSZEN(1:knon)))**2 + &
129               ((ZCOSZEN(1:knon)-1.34*ZXX2(1:knon))/(ZCOSZEN(1:knon)+1.34*ZXX2(1:knon)))**2)
130  ZR11(1:knon)=ZRR0(1:knon)-(0.0152-1.7873*ZCOSZEN(1:knon)+6.8972*ZCOSZEN(1:knon)**2-8.5778*ZCOSZEN(1:knon)**3+ &
131               4.071*ZSIG(1:knon)-7.6446*ZCOSZEN(1:knon)*ZSIG(1:knon)) *  &
132               EXP(0.1643-7.8409*ZCOSZEN(1:knon)-3.5639*ZCOSZEN(1:knon)**2-2.3588*ZSIG(1:knon)+ &
133               10.0538*ZCOSZEN(1:knon)*ZSIG(1:knon))*ZRR0(1:knon)/ZRRR(1:knon)
134  !
135  !---------------------------------------------------------------------------------
136  ! 2- Compute surface diffuse albedo (ZRDF)
137  !---------------------------------------------------------------------------------
138  ! Diffuse albedo from Jin et al., 2006 + estimation from diffuse fraction of
139  ! light (relying later on AOD). CNRM model has opted for Eq 5b
140  ZRDF(1:knon)=-0.1482-0.012*ZSIG(1:knon)+0.1609*ZREFM-0.0244*ZSIG(1:knon)*ZREFM ! surface diffuse (Eq 5a)
141  !!ZRDF(1:knon)=-0.1479+0.1502*ZREFM-0.0176*ZSIG(1:knon)*ZREFM   ! surface diffuse (Eq 5b)
142 
143  !---------------------------------------------------------------------------------
144  ! *- Determine absorption and backscattering
145  ! coefficients to determine reflectance below the surface (Ro) once for all
146  !
147  ! *.1- Absorption by chlorophyll
148  ZCHLABS= XAKACHL(JWL)
149  ! *.2- Absorption by seawater
150  ZAW= XAKAW3(JWL)
151  ! *.3- Backscattering by seawater
152  ZBW= XAKBW(JWL)
153  ! *.4- Backscattering by chlorophyll
154  ZYLMD = EXP(0.014*(440.0-ZWL))
155  ZAP(1:knon) = 0.06*ZCHLABS*ZWORK1(1:knon) +0.2*(XAW440+0.06*ZWORK1(1:knon))*ZYLMD
156   
157!!  WHERE ( ZCHL(1:knon) > 0.02 )
158!!    ZNU(:)=MIN(0.0,0.5*(ZWORK3(:)-0.3))
159!!    ZBBP(:)=(0.002+0.01*(0.5-0.25*ZWORK3(:))*(ZWL/550.)**ZNU(:))*ZWORK2(:)
160!!  ELSEWHERE
161!!    ZBBP(:)=0.019*(550./ZWL)*ZWORK2(:)       !ZBBPf=0.0113 at chl<=0.02
162!!  ENDWHERE
163
164    do JI = 1, knon
165      IF (ZCHL(JI) > 0.02) THEN
166        ZNU(JI)=MIN(0.0,0.5*(ZWORK3(JI)-0.3))
167        ZBBP(JI)=(0.002+0.01*(0.5-0.25*ZWORK3(JI))*(ZWL/550.)**ZNU(JI)) &
168                  *ZWORK2(JI)
169      ELSE
170        ZBBP(JI)=0.019*(550./ZWL)*ZWORK2(JI)       !ZBBPf=0.0113 at chl<=0.02
171      ENDIF
172    ENDDO
173
174  ! Morel-Gentili(1991), Eq (12)
175  ! ZHB=h/(h+2*ZBBPf*(1.-h))       
176  ZHB(1:knon)=0.5*ZBW/(0.5*ZBW+ZBBP(1:knon))
177   
178  !---------------------------------------------------------------------------------
179  ! 3- Compute direct water-leaving albedo (ZRW)
180  !---------------------------------------------------------------------------------
181  ! Based on Morel & Gentilli 1991 parametrization
182  ZR22(1:knon)=0.48168549-0.014894708*ZSIG(1:knon)-0.20703885*ZSIG(1:knon)**2
183
184  ! Use Morel 91 formula to compute the direct reflectance
185  ! below the surface
186  ZR00(1:knon)=(0.5*ZBW+ZBBP(1:knon))/(ZAW+ZAP(1:knon)) *  &
187               (0.6279-0.2227*ZHB(1:knon)-0.0513*ZHB(1:knon)**2 + &
188               (-0.3119+0.2465*ZHB(1:knon))*ZCOSZEN(1:knon))
189  ZRW(1:knon)=ZR00(1:knon)*(1.-ZR22(1:knon))/(1.-ZR00(1:knon)*ZR22(1:knon))
190
191  !---------------------------------------------------------------------------------
192  ! 4- Compute diffuse water-leaving albedo (ZRWDF)
193  !---------------------------------------------------------------------------------
194  ! as previous water-leaving computation but assumes a uniform incidence of
195  ! shortwave at surface (ue)
196  ZUE=0.676               ! equivalent u_unif for diffuse incidence
197  ZUE2=SQRT(1.0-(1.0-ZUE**2)/ZREFM**2)
198  ZRR0(1:knon)=0.50*(((ZUE2-ZREFM*ZUE)/(ZUE2+ZREFM*ZUE))**2 +((ZUE-ZREFM*ZUE2)/(ZUE+ZREFM*ZUE2))**2)
199  ZRRR(1:knon)=0.50*(((ZUE2-1.34*ZUE)/(ZUE2+1.34*ZUE))**2 +((ZUE-1.34*ZUE2)/(ZUE+1.34*ZUE2))**2)
200  ZR11DF(1:knon)=ZRR0(1:knon)-(0.0152-1.7873*ZUE+6.8972*ZUE**2-8.5778*ZUE**3+4.071*ZSIG(1:knon)-7.6446*ZUE*ZSIG(1:knon)) * &
201                 EXP(0.1643-7.8409*ZUE-3.5639*ZUE**2-2.3588*ZSIG(1:knon)+10.0538*ZUE*ZSIG(1:knon))*ZRR0(1:knon)/ZRRR(1:knon)
202
203  ! Use Morel 91 formula to compute the diffuse
204  ! reflectance below the surface
205  ZR00(1:knon) = (0.5*ZBW+ZBBP(1:knon)) / (ZAW+ZAP(1:knon)) &
206       * (0.6279-0.2227*ZHB(1:knon)-0.0513*ZHB(1:knon)**2 &
207       + (-0.3119+0.2465*ZHB(1:knon))*ZUE)
208  ZRWDF(1:knon)=ZR00(1:knon)*(1.-ZR22(1:knon))*(1.-ZR11DF(1:knon))/(1.-ZR00(1:knon)*ZR22(1:knon))
209   
210  ! get waveband index inu for each nsw band
211  SELECT CASE(nsw)
212  CASE(2)
213    IF (JWL.LE.49) THEN       ! from 200  to 680 nm
214     inu=1
215    ELSE                      ! from 690  to 4000 nm
216     inu=2
217    ENDIF
218  CASE(4)
219    IF (JWL.LE.49) THEN       ! from 200  to 680 nm
220     inu=1
221    ELSE IF (JWL.LE.99) THEN  ! from 690  to 1180 nm
222     inu=2
223    ELSE IF (JWL.LE.218) THEN ! from 1190 to 2370 nm
224     inu=3
225    ELSE                      ! from 2380 to 4000 nm
226     inu=4
227    ENDIF
228  CASE(6)
229    IF (JWL.LE.5) THEN        ! from 200  to 240 nm
230     inu=1
231    ELSE IF (JWL.LE.24) THEN  ! from 250  to 430 nm
232     inu=2
233    ELSE IF (JWL.LE.49) THEN  ! from 440  to 680 nm
234     inu=3
235    ELSE IF (JWL.LE.99) THEN  ! from 690  to 1180 nm
236     inu=4
237    ELSE IF (JWL.LE.218) THEN ! from 1190 to 2370 nm
238     inu=5
239    ELSE                      ! from 2380 to 4000 nm
240     inu=6
241    ENDIF
242  END SELECT
243
244  ! partitionning direct and diffuse albedo
245  ! excluding diffuse albedo ZRW on ZDIR_ALB
246
247  !--direct
248  alb_dir_new(1:knon,inu)=alb_dir_new(1:knon,inu) + &
249                          ( XFRWL(JWL) * ((1.-ZFWC(1:knon)) * (ZR11(1:knon)+ZRW(1:knon))   + ZFWC(1:knon)*XRWC(JWL)) )/SFRWL(inu)
250  !--diffuse
251  alb_dif_new(1:knon,inu)=alb_dif_new(1:knon,inu) + &
252                          ( XFRWL(JWL) * ((1.-ZFWC(1:knon)) * (ZRDF(1:knon)+ZRWDF(1:knon)) + ZFWC(1:knon)*XRWC(JWL)) )/SFRWL(inu)
253
254ENDDO ! ending loop over wavelengths
255
256END SUBROUTINE ocean_albedo
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