! ! $Id$ ! ! ######### subroutine ocean_albedo(knon,zrmu0,knindex,pwind,SFRWL,alb_dir_new,alb_dif_new) ! ################################################################## ! !!**** *ALBEDO_RS14* !! !! PURPOSE !! ------- ! computes the direct & diffuse albedo over open water ! ! !!** METHOD !! ------ ! !! EXTERNAL !! -------- !! !! IMPLICIT ARGUMENTS !! ------------------ !! !! !! REFERENCE !! --------- !! !! !! AUTHOR !! ------ !! R. Séférian * Meteo-France * !! !! MODIFICATIONS !! ------------- !! Original 03/2014 ! 05/2014 R. Séférian & B. Decharme :: Adaptation to spectral ! computation for diffuse and direct albedo ! 08/2014 S. Baek :: for wider wavelength range 200-4000nm and ! adaptation to LMDZ + whitecap effect by Koepke + chrolophyll ! map from climatology file ! !------------------------------------------------------------------------------- ! !* DECLARATIONS ! ------------ ! USE ocean_albedo_para use dimphy !LF USE PARKIND1 ,ONLY : JPIM ,JPRB use phys_state_var_mod, only : chl_con ! ! IMPLICIT NONE ! !* 0.1 declarations of arguments ! ------------------------- ! include "clesphys.h" integer, intent(in) :: knon integer, dimension(klon), intent(in) :: knindex real, dimension(klon), intent(in) :: zrmu0,pwind real, dimension(klon,nsw), intent(out) :: alb_dir_new,alb_dif_new real, dimension(6),intent(in) :: SFRWL !=== LOCAL VARIABLES REAL, parameter :: XPI=4.*atan(1.) ! !* 0.2 declarations of local variables ! ------------------------- ! REAL, DIMENSION(klon) :: ZCHL ! surface chlorophyll REAL, DIMENSION(klon,NNWL) :: ZDIR_ALB ! direct ocean surface albedo (spectral) REAL, DIMENSION(klon,NNWL) :: ZSCA_ALB ! diffuse ocean surface albedo (spectral) ! INTEGER :: JI, JWL ! indexes REAL :: ZWL ! input parameter: wavelength and diffuse/direct fraction of light REAL:: ZSIG, ZREFM, ZXX2, ZR00, ZRR0, ZRRR ! computation variables REAL:: ZR22, ZUE, ZUE2, ZR11DF, ZALBT, ZFWC ! computation variables REAL:: ZCHLABS, ZAW, ZBW, ZAP, ZYLMD, ZBP550 ! computation variables REAL:: ZBBP, ZNU, ZHB ! computation variables REAL:: ZCOSZEN ! Cosine of the zenith solar angle REAL:: ZR11, ZRW, ZRWDF, ZRDF ! 4 components of the OSA ! new damping coefficient REAL:: ZDAMP ! REAL :: ZWORK ! dummy variable ! !LF REAL(KIND=JPRB) :: ZHOOK_HANDLE ! !------------------------------------------------------------------------------- ! ! ! alb_dir_new(:,:) = 0. alb_dif_new(:,:) = 0. ! ZDIR_ALB(:,:) = 0. ZSCA_ALB(:,:) = 0. ! ! !ZCHL(:) = CHL_CON!0.05 ! averaged global values for surface chlorophyll if(ok_chlorophyll)then do ji=1,knon ZCHL(ji)=CHL_CON(knindex(ji)) enddo else ZCHL(:) = 0.05 endif ! DO JWL=1,NNWL ! loop over the wavelength ! DO JI=1,knon ! loop over the grid points !--------------------------------------------------------------------------------- ! 0- Compute baseline values !--------------------------------------------------------------------------------- ! Get refractive index for the correspoding wavelength ZWL=XAKWL(JWL) !!!---------- wavelength value ZREFM= XAKREFM(JWL) !!!--------- refraction index value ! compute the cosine of the solar zenith angle ! ZCOSZEN = COS(XPI/2 - PZENITH(JI)) ZCOSZEN = zrmu0(knindex(JI)) ! Compute sigma derived from wind speed (Cox & Munk reflectance model) ZSIG=SQRT(0.003+0.00512*PWIND(JI)) !--------------------------------------------------------------------------------- ! 1- Compute direct surface albedo (ZR11) !--------------------------------------------------------------------------------- ! ZXX2=SQRT(1.0-(1.0-ZCOSZEN**2)/ZREFM**2) ZRR0=0.50*(((ZXX2-ZREFM*ZCOSZEN)/(ZXX2+ZREFM*ZCOSZEN))**2 +((ZCOSZEN-ZREFM*ZXX2)/(ZCOSZEN+ZREFM*ZXX2))**2) ZRRR=0.50*(((ZXX2-1.34*ZCOSZEN)/(ZXX2+1.34*ZCOSZEN))**2 +((ZCOSZEN-1.34*ZXX2)/(ZCOSZEN+1.34*ZXX2))**2) ZR11=ZRR0-(0.0152-1.7873*ZCOSZEN+6.8972*ZCOSZEN**2-8.5778*ZCOSZEN**3+4.071*ZSIG-7.6446*ZCOSZEN*ZSIG) & & * EXP(0.1643-7.8409*ZCOSZEN-3.5639*ZCOSZEN**2-2.3588*ZSIG+10.0538*ZCOSZEN*ZSIG)*ZRR0/ZRRR ! !--------------------------------------------------------------------------------- ! 2- Compute surface diffuse albedo (ZRDF) !--------------------------------------------------------------------------------- ! Diffuse albedo from Jin et al., 2006 + estimation from diffuse fraction of ! light (relying later on AOD) ZRDF=-0.1482-0.012*ZSIG+0.1609*ZREFM-0.0244*ZSIG*ZREFM ! surface diffuse (Eq 5a-5b) !--------------------------------------------------------------------------------- ! *- Determine absorption and backscattering ! coefficients to determine reflectance below the surface (Ro) once for all ! ! *.1- Absorption by chlorophyll ZCHLABS= XAKACHL(JWL) ! *.2- Absorption by seawater ZAW= XAKAW3(JWL) ! *.3- Backscattering by seawater ZBW= XAKBW(JWL) ! *.4- Backscattering by chlorophyll ZYLMD = EXP(0.014*(440.0-ZWL)) ZWORK= EXP(LOG(ZCHL(JI))*0.65) ZAP = 0.06*ZCHLABS*ZWORK +0.2*(XAW440+0.06*ZWORK)*ZYLMD ZBP550 = 0.416 * EXP(LOG(ZCHL(JI))*0.766) IF ( ZCHL(JI) > 2. ) THEN ZNU=0. ELSE IF ( ZCHL(JI) > 0.02 ) THEN ZWORK=LOG10(ZCHL(JI)) ZNU=0.5*(ZWORK-0.3) ZBBP=(0.002+0.01*(0.5-0.25*ZWORK)*(ZWL/550.)**ZNU)*ZBP550 ELSE ZBBP=0.019*(550./ZWL)*ZBP550 !ZBBPf=0.0113 at chl<=0.02 ENDIF ENDIF ! Morel-Gentili(1991), Eq (12) ! ZHB=h/(h+2*ZBBPf*(1.-h)) ZHB=0.5*ZBW/(0.5*ZBW+ZBBP) !--------------------------------------------------------------------------------- ! 3- Compute direct water-leaving albedo (ZRW) !--------------------------------------------------------------------------------- ! Based on Morel & Gentilli 1991 parametrization ZR22=0.48168549-0.014894708*ZSIG-0.20703885*ZSIG**2 ! Use Morel 91 formula to compute the direct reflectance ! below the surface ZR00=(0.5*ZBW+ZBBP)/(ZAW+ZAP) *(0.6279-0.2227*ZHB-0.0513*ZHB**2 + (-0.3119+0.2465*ZHB)*ZCOSZEN) ZRW=ZR00*(1.-ZR22)*(1.-ZR11)/(1.-ZR00*ZR22) ZRW=ZR00*(1.-ZR22)/(1.-ZR00*ZR22) !--------------------------------------------------------------------------------- ! 4- Compute diffuse water-leaving albedo (ZRWDF) !--------------------------------------------------------------------------------- ! as previous water-leaving computation but assumes a uniform incidence of ! shortwave at surface (ue) ZUE=0.676 ! equivalent u_unif for diffuse incidence ZUE2=SQRT(1.0-(1.0-ZUE**2)/ZREFM**2) ZRR0=0.50*(((ZUE2-ZREFM*ZUE)/(ZUE2+ZREFM*ZUE))**2 +((ZUE-ZREFM*ZUE2)/(ZUE+ZREFM*ZUE2))**2) ZRRR=0.50*(((ZUE2-1.34*ZUE)/(ZUE2+1.34*ZUE))**2 +((ZUE-1.34*ZUE2)/(ZUE+1.34*ZUE2))**2) ZR11DF=ZRR0-(0.0152-1.7873*ZUE+6.8972*ZUE**2-8.5778*ZUE**3+4.071*ZSIG-7.6446*ZUE*ZSIG) & & * EXP(0.1643-7.8409*ZUE-3.5639*ZUE**2-2.3588*ZSIG+10.0538*ZUE*ZSIG)*ZRR0/ZRRR ! Use Morel 91 formula to compute the diffuse ! reflectance below the surface ZR00=(0.5*ZBW+ZBBP)/(ZAW+ZAP) *(0.6279-0.2227*ZHB-0.0513*ZHB**2 + (-0.3119+0.2465*ZHB)*ZUE) ZRWDF=ZR00*(1.-ZR22)*(1.-ZR11DF)/(1.-ZR00*ZR22) ! original : correction for foam (Eq 16-17) ZFWC=3.97e-4*PWIND(JI)**(1.59) ! Salisbury 2014 eq(2) at 37GHz, value in fraction ! has to be update once we have information from wave model (discussion with G. Madec) ! -------------------------------------------------------------------- ! *- OSA estimation ! -------------------------------------------------------------------- ! partitionning direct and diffuse albedo ! ! excluding diffuse albedo ZRW on ZDIR_ALB ZDIR_ALB(JI,JWL) = XFRWL(JWL) *((1.-ZFWC) * (ZR11+ZRW) +ZFWC*XRWC(JWL)) ZSCA_ALB(JI,JWL) = XFRWL(JWL) *((1.-ZFWC) * (ZRDF+ZRWDF) + ZFWC*XRWC(JWL)) ! print*,ji,ZFWC,ZDIR_ALB(JI,JWL),ZSCA_ALB(JI,JWL),pwind(ji) ENDDO ! end of the loop over grid points ENDDO ! ending loop over wavelengths ! integral for each nsw band select case(nsw) case(2) do ji=1,knon alb_dir_new(ji,1)=sum(zdir_alb(ji,1:49))/SFRWL(1) ! from 200nm to 680nm alb_dir_new(ji,2)=sum(zdir_alb(ji,50:381))/SFRWL(2) ! from 690nm to 4000 nm alb_dif_new(ji,1)=sum(zsca_alb(ji,1:49))/SFRWL(1) ! from 200nm to 680nm alb_dif_new(ji,2)=sum(zsca_alb(ji,50:381))/SFRWL(2) ! from 690nm to 4000 nm enddo case(4) do ji=1,knon alb_dir_new(ji,1)=sum(zdir_alb(ji,1:49))/SFRWL(1) ! from 200nm to 680nm alb_dir_new(ji,2)=sum(zdir_alb(ji,50:99))/SFRWL(2) ! from 690nm to 1180 nm alb_dir_new(ji,3)=sum(zdir_alb(ji,100:218))/SFRWL(3) ! from 1190nm to 2370 nm alb_dir_new(ji,4)=sum(zdir_alb(ji,219:381))/SFRWL(4) ! from 2380nm to 4000 nm alb_dif_new(ji,1)=sum(zsca_alb(ji,1:49))/SFRWL(1) ! from 200nm to 680nm alb_dif_new(ji,2)=sum(zsca_alb(ji,50:99))/SFRWL(2) ! from 690nm to 1180 nm alb_dif_new(ji,3)=sum(zsca_alb(ji,100:218))/SFRWL(3) ! from 1190nm to 2370 nm alb_dif_new(ji,4)=sum(zsca_alb(ji,219:381))/SFRWL(4) ! from 2380nm to 4000 nm enddo case(6) do ji=1,knon alb_dir_new(ji,1)=sum(zdir_alb(ji,1:5))/SFRWL(1) ! from 200nm to 240nm alb_dir_new(ji,2)=sum(zdir_alb(ji,6:24))/SFRWL(2) ! from 250nm to 430 nm alb_dir_new(ji,3)=sum(zdir_alb(ji,25:49))/SFRWL(3) ! from 440nm to 680 nm alb_dir_new(ji,4)=sum(zdir_alb(ji,50:99))/SFRWL(4) ! from 690nm to 1180 nm alb_dir_new(ji,5)=sum(zdir_alb(ji,100:218))/SFRWL(5) ! from 1190nm to 2370 nm alb_dir_new(ji,6)=sum(zdir_alb(ji,219:381))/SFRWL(6) ! from 2380nm to 4000 nm alb_dif_new(ji,1)=sum(zsca_alb(ji,1:5))/SFRWL(1) ! from 200nm to 240nm alb_dif_new(ji,2)=sum(zsca_alb(ji,6:24))/SFRWL(2) ! from 250nm to 430 nm alb_dif_new(ji,3)=sum(zsca_alb(ji,25:49))/SFRWL(3) ! from 440nm to 680 nm alb_dif_new(ji,4)=sum(zsca_alb(ji,50:99))/SFRWL(4) ! from 690nm to 1180 nm alb_dif_new(ji,5)=sum(zsca_alb(ji,100:218))/SFRWL(5) ! from 1190nm to 2370 nm alb_dif_new(ji,6)=sum(zsca_alb(ji,219:381))/SFRWL(6) ! from 2380nm to 4000 nm enddo end select END subroutine ocean_albedo