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SUBROUTINE lidar_simulator(npoints,nlev,npart,nrefl & , undef & , pres, presf, temp & , q_lsliq, q_lsice, q_cvliq, q_cvice & , ls_radliq, ls_radice, cv_radliq, cv_radice & , ice_type, pmol, pnorm, pnorm_perp_tot,tautot, refl ) ! !--------------------------------------------------------------------------------- ! Purpose: To compute lidar signal from model-simulated profiles of cloud water ! and cloud fraction in each sub-column of each model gridbox. ! ! References: ! Chepfer H., S. Bony, D. Winker, M. Chiriaco, J.-L. Dufresne, G. Seze (2008), ! Use of CALIPSO lidar observations to evaluate the cloudiness simulated by a ! climate model, Geophys. Res. Lett., 35, L15704, doi:10.1029/2008GL034207. ! ! Previous references: ! Chiriaco et al, MWR, 2006; Chepfer et al., MWR, 2007 ! ! Contacts: Helene Chepfer (chepfer@lmd.polytechnique.fr), Sandrine Bony (bony@lmd.jussieu.fr) ! ! May 2007: ActSim code of M. Chiriaco and H. Chepfer rewritten by S. Bony ! ! May 2008, H. Chepfer: ! - Units of pressure inputs: Pa ! - Non Spherical particles : LS Ice NS coefficients, CONV Ice NS coefficients ! - New input: ice_type (0=ice-spheres ; 1=ice-non-spherical) ! ! June 2008, A. Bodas-Salcedo: ! - Ported to Fortran 90 and optimisation changes ! ! August 2008, J-L Dufresne: ! - Optimisation changes (sum instructions suppressed) ! ! October 2008, S. Bony, H. Chepfer and J-L. Dufresne : ! - Interface with COSP v2.0: ! cloud fraction removed from inputs ! in-cloud condensed water now in input (instead of grid-averaged value) ! depolarisation diagnostic removed ! parasol (polder) reflectances (for 5 different solar zenith angles) added ! ! December 2008, S. Bony, H. Chepfer and J-L. Dufresne : ! - Modification of the integration of the lidar equation. ! - change the cloud detection threshold ! ! April 2008, A. Bodas-Salcedo: ! - Bug fix in computation of pmol and pnorm of upper layer ! ! April 2008, J-L. Dufresne ! - Bug fix in computation of pmol and pnorm, thanks to Masaki Satoh: a factor 2 ! was missing. This affects the ATB values but not the cloud fraction. ! ! January 2013, G. Cesana and H. Chepfer: ! - Add the perpendicular component of the backscattered signal (pnorm_perp_tot) in the arguments ! - Add the temperature for each levels (temp) in the arguments ! - Add the computation of the perpendicular component of the backscattered lidar signal ! Reference: Cesana G. and H. Chepfer (2013): Evaluation of the cloud water phase ! in a climate model using CALIPSO-GOCCP, J. Geophys. Res., doi: 10.1002/jgrd.50376 ! !--------------------------------------------------------------------------------- ! ! Inputs: ! npoints : number of horizontal points ! nlev : number of vertical levels ! npart: numberb of cloud meteors (stratiform_liq, stratiform_ice, conv_liq, conv_ice). ! Currently npart must be 4 ! nrefl: number of solar zenith angles for parasol reflectances ! pres : pressure in the middle of atmospheric layers (full levels): Pa ! presf: pressure in the interface of atmospheric layers (half levels): Pa ! presf(..,1) : surface pressure ; presf(..,nlev+1)= TOA pressure ! temp : temperature of atmospheric layers: K ! q_lsliq: LS sub-column liquid water mixing ratio (kg/kg) ! q_lsice: LS sub-column ice water mixing ratio (kg/kg) ! q_cvliq: CONV sub-column liquid water mixing ratio (kg/kg) ! q_cvice: CONV sub-column ice water mixing ratio (kg/kg) ! ls_radliq: effective radius of LS liquid particles (meters) ! ls_radice: effective radius of LS ice particles (meters) ! cv_radliq: effective radius of CONV liquid particles (meters) ! cv_radice: effective radius of CONV ice particles (meters) ! ice_type : ice particle shape hypothesis (ice_type=0 for spheres, ice_type=1 ! for non spherical particles) ! ! Outputs: ! pmol : molecular attenuated backscatter lidar signal power (m^-1.sr^-1) ! pnorm: total attenuated backscatter lidar signal power (m^-1.sr^-1) ! pnorm_perp_tot: perpendicular attenuated backscatter lidar signal power (m^-1.sr^-1) ! tautot: optical thickess integrated from top to level z ! refl : parasol(polder) reflectance ! ! Version 1.0 (June 2007) ! Version 1.1 (May 2008) ! Version 1.2 (June 2008) ! Version 2.0 (October 2008) ! Version 2.1 (December 2008) !--------------------------------------------------------------------------------- USE MOD_COSP_CONSTANTS, only : ok_debug_cosp IMPLICIT NONE REAL :: SRsat PARAMETER (SRsat = 0.01) ! threshold full attenuation LOGICAL ok_parasol PARAMETER (ok_parasol=.true.) ! set to .true. if you want to activate parasol reflectances INTEGER i, k INTEGER INDX_LSLIQ,INDX_LSICE,INDX_CVLIQ,INDX_CVICE PARAMETER (INDX_LSLIQ=1,INDX_LSICE=2,INDX_CVLIQ=3,INDX_CVICE=4) ! inputs: INTEGER npoints,nlev,npart,ice_type INTEGER nrefl real undef ! undefined value REAL pres(npoints,nlev) ! pressure full levels REAL presf(npoints,nlev+1) ! pressure half levels REAL q_lsliq(npoints,nlev), q_lsice(npoints,nlev) REAL q_cvliq(npoints,nlev), q_cvice(npoints,nlev) REAL ls_radliq(npoints,nlev), ls_radice(npoints,nlev) REAL cv_radliq(npoints,nlev), cv_radice(npoints,nlev) ! outputs (for each subcolumn): REAL pmol(npoints,nlev) ! molecular backscatter signal power (m^-1.sr^-1) REAL pnorm(npoints,nlev) ! total lidar backscatter signal power (m^-1.sr^-1) REAL tautot(npoints,nlev)! optical thickess integrated from top REAL refl(npoints,nrefl)! parasol reflectance ! parasol ! actsim variables: REAL km, rdiffm, Qscat, Cmol PARAMETER (Cmol = 6.2446e-32) ! depends on wavelength PARAMETER (km = 1.38e-23) ! Boltzmann constant (J/K) PARAMETER (rdiffm = 0.7) ! multiple scattering correction parameter PARAMETER (Qscat = 2.0) ! particle scattering efficiency at 532 nm REAL rholiq, rhoice PARAMETER (rholiq=1.0e+03) ! liquid water (kg/m3) PARAMETER (rhoice=0.5e+03) ! ice (kg/m3) REAL pi, rhopart(npart) REAL polpart(npart,5) ! polynomial coefficients derived for spherical and non spherical ! particules ! grid-box variables: REAL rad_part(npoints,nlev,npart) REAL rhoair(npoints,nlev), zheight(npoints,nlev+1) REAL beta_mol(npoints,nlev), alpha_mol(npoints,nlev) REAL kp_part(npoints,nlev,npart) ! sub-column variables: REAL qpart(npoints,nlev,npart) ! mixing ratio particles in each subcolumn REAL alpha_part(npoints,nlev,npart) REAL tau_mol_lay(npoints) ! temporary variable, moL. opt. thickness of layer k REAL tau_mol(npoints,nlev) ! optical thickness between TOA and bottom of layer k REAL tau_part(npoints,nlev,npart) REAL betatot(npoints,nlev) REAL tautot_lay(npoints) ! temporary variable, total opt. thickness of layer k ! Optical thickness from TOA to surface for Parasol REAL tautot_S_liq(npoints),tautot_S_ice(npoints) ! for liq and ice clouds ! Local variables REAL Alpha, Beta, Gamma ! Polynomial coefficient for ATBperp computation REAL temp(npoints,nlev) ! temperature of layer k REAL betatot_ice(npoints,nlev) ! backscatter coefficient for ice particles REAL beta_perp_ice(npoints,nlev) ! perpendicular backscatter coefficient for ice REAL betatot_liq(npoints,nlev) ! backscatter coefficient for liquid particles REAL beta_perp_liq(npoints,nlev) ! perpendicular backscatter coefficient for liq REAL tautot_ice(npoints,nlev) ! total optical thickness of ice REAL tautot_liq(npoints,nlev) ! total optical thickness of liq REAL tautot_lay_ice(npoints) ! total optical thickness of ice in the layer k REAL tautot_lay_liq(npoints) ! total optical thickness of liq in the layer k REAL pnorm_liq(npoints,nlev) ! lidar backscattered signal power for liquid REAL pnorm_ice(npoints,nlev) ! lidar backscattered signal power for ice REAL pnorm_perp_ice(npoints,nlev) ! perpendicular lidar backscattered signal power for ice REAL pnorm_perp_liq(npoints,nlev) ! perpendicular lidar backscattered signal power for liq REAL :: seuil ! Output variable REAL pnorm_perp_tot (npoints,nlev) ! perpendicular lidar backscattered signal power !------------------------------------------------------------ !---- 0. Initialisation : !------------------------------------------------------------ betatot_ice(:,:)=0 betatot_liq(:,:)=0 beta_perp_ice(:,:)=0 beta_perp_liq(:,:)=0 tautot_ice(:,:)=0 tautot_liq(:,:)=0 tautot_lay_ice(:)=0; tautot_lay_liq(:)=0; pnorm_liq(:,:)=0 pnorm_ice(:,:)=0 pnorm_perp_ice(:,:)=0 pnorm_perp_liq(:,:)=0 pnorm_perp_tot(:,:)=0 ! Polynomial coefficients (Alpha, Beta, Gamma) which allow to compute the ATBperpendicular ! as a function of the ATB for ice or liquid cloud particles derived from CALIPSO-GOCCP ! observations at 120m vertical grid (Cesana and Chepfer, JGR, 2013). ! ! Relationship between ATBice and ATBperp,ice for ice particles ! ATBperp,ice = Alpha*ATBice Alpha = 0.2904 ! Relationship between ATBice and ATBperp,ice for liquid particles ! ATBperp,ice = Beta*ATBice^2 + Gamma*ATBice Beta = 0.4099 Gamma = 0.009 if (ok_debug_cosp) then seuil=1.e-18 else seuil=0.0 endif !------------------------------------------------------------ !---- 1. Preliminary definitions and calculations : !------------------------------------------------------------ if ( npart .ne. 4 ) then print *,'Error in lidar_simulator, npart should be 4, not',npart stop endif pi = dacos(-1.D0) ! Polynomial coefficients for spherical liq/ice particles derived from Mie theory. ! Polynomial coefficients for non spherical particles derived from a composite of ! Ray-tracing theory for large particles (e.g. Noel et al., Appl. Opt., 2001) ! and FDTD theory for very small particles (Yang et al., JQSRT, 2003). ! We repeat the same coefficients for LS and CONV cloud to make code more readable !* LS Liquid water coefficients: polpart(INDX_LSLIQ,1) = 2.6980e-8 polpart(INDX_LSLIQ,2) = -3.7701e-6 polpart(INDX_LSLIQ,3) = 1.6594e-4 polpart(INDX_LSLIQ,4) = -0.0024 polpart(INDX_LSLIQ,5) = 0.0626 !* LS Ice coefficients: if (ice_type.eq.0) then polpart(INDX_LSICE,1) = -1.0176e-8 polpart(INDX_LSICE,2) = 1.7615e-6 polpart(INDX_LSICE,3) = -1.0480e-4 polpart(INDX_LSICE,4) = 0.0019 polpart(INDX_LSICE,5) = 0.0460 endif !* LS Ice NS coefficients: if (ice_type.eq.1) then polpart(INDX_LSICE,1) = 1.3615e-8 polpart(INDX_LSICE,2) = -2.04206e-6 polpart(INDX_LSICE,3) = 7.51799e-5 polpart(INDX_LSICE,4) = 0.00078213 polpart(INDX_LSICE,5) = 0.0182131 endif !* CONV Liquid water coefficients: polpart(INDX_CVLIQ,1) = 2.6980e-8 polpart(INDX_CVLIQ,2) = -3.7701e-6 polpart(INDX_CVLIQ,3) = 1.6594e-4 polpart(INDX_CVLIQ,4) = -0.0024 polpart(INDX_CVLIQ,5) = 0.0626 !* CONV Ice coefficients: if (ice_type.eq.0) then polpart(INDX_CVICE,1) = -1.0176e-8 polpart(INDX_CVICE,2) = 1.7615e-6 polpart(INDX_CVICE,3) = -1.0480e-4 polpart(INDX_CVICE,4) = 0.0019 polpart(INDX_CVICE,5) = 0.0460 endif if (ice_type.eq.1) then polpart(INDX_CVICE,1) = 1.3615e-8 polpart(INDX_CVICE,2) = -2.04206e-6 polpart(INDX_CVICE,3) = 7.51799e-5 polpart(INDX_CVICE,4) = 0.00078213 polpart(INDX_CVICE,5) = 0.0182131 endif ! density: !* clear-sky air: rhoair = pres/(287.04*temp) !* liquid/ice particules: rhopart(INDX_LSLIQ) = rholiq rhopart(INDX_LSICE) = rhoice rhopart(INDX_CVLIQ) = rholiq rhopart(INDX_CVICE) = rhoice ! effective radius particles: rad_part(:,:,INDX_LSLIQ) = ls_radliq(:,:) rad_part(:,:,INDX_LSICE) = ls_radice(:,:) rad_part(:,:,INDX_CVLIQ) = cv_radliq(:,:) rad_part(:,:,INDX_CVICE) = cv_radice(:,:) rad_part(:,:,:)=MAX(rad_part(:,:,:),0.) rad_part(:,:,:)=MIN(rad_part(:,:,:),70.0e-6) ! altitude at half pressure levels: zheight(:,1) = 0.0 do k = 2, nlev+1 zheight(:,k) = zheight(:,k-1) & -(presf(:,k)-presf(:,k-1))/(rhoair(:,k-1)*9.81) enddo !------------------------------------------------------------ !---- 2. Molecular alpha and beta: !------------------------------------------------------------ beta_mol = pres/km/temp * Cmol alpha_mol = 8.0*pi/3.0 * beta_mol !------------------------------------------------------------ !---- 3. Particles alpha and beta: !------------------------------------------------------------ ! polynomes kp_lidar derived from Mie theory: do i = 1, npart where ( rad_part(:,:,i).gt.0.0) kp_part(:,:,i) = & polpart(i,1)*(rad_part(:,:,i)*1e6)**4 & + polpart(i,2)*(rad_part(:,:,i)*1e6)**3 & + polpart(i,3)*(rad_part(:,:,i)*1e6)**2 & + polpart(i,4)*(rad_part(:,:,i)*1e6) & + polpart(i,5) elsewhere kp_part(:,:,i) = 0. endwhere enddo ! mixing ratio particules in each subcolumn: qpart(:,:,INDX_LSLIQ) = q_lsliq(:,:) ! oct08 qpart(:,:,INDX_LSICE) = q_lsice(:,:) ! oct08 qpart(:,:,INDX_CVLIQ) = q_cvliq(:,:) ! oct08 qpart(:,:,INDX_CVICE) = q_cvice(:,:) ! oct08 ! alpha of particles in each subcolumn: do i = 1, npart where ( rad_part(:,:,i).gt.0.0) alpha_part(:,:,i) = 3.0/4.0 * Qscat & * rhoair(:,:) * qpart(:,:,i) & / (rhopart(i) * rad_part(:,:,i) ) elsewhere alpha_part(:,:,i) = 0. endwhere enddo !------------------------------------------------------------ !---- 4.1 Total Backscatter signal: !------------------------------------------------------------ ! optical thickness (molecular): ! opt. thick of each layer tau_mol(:,1:nlev) = alpha_mol(:,1:nlev) & & *(zheight(:,2:nlev+1)-zheight(:,1:nlev)) ! opt. thick from TOA DO k = nlev-1, 1, -1 tau_mol(:,k) = tau_mol(:,k) + tau_mol(:,k+1) ENDDO ! optical thickness (particles): tau_part = rdiffm * alpha_part DO i = 1, npart ! opt. thick of each layer tau_part(:,:,i) = tau_part(:,:,i) & & * (zheight(:,2:nlev+1)-zheight(:,1:nlev) ) ! opt. thick from TOA DO k = nlev-1, 1, -1 tau_part(:,k,i) = tau_part(:,k,i) + tau_part(:,k+1,i) ENDDO ENDDO ! molecular signal: ! Upper layer pmol(:,nlev) = beta_mol(:,nlev) / (2.*tau_mol(:,nlev)) & & * (1.-exp(-2.0*tau_mol(:,nlev))) ! Other layers DO k= nlev-1, 1, -1 tau_mol_lay(:) = tau_mol(:,k)-tau_mol(:,k+1) ! opt. thick. of layer k WHERE (tau_mol_lay(:).GT.0.) pmol(:,k) = beta_mol(:,k) * EXP(-2.0*tau_mol(:,k+1)) / (2.*tau_mol_lay(:)) & & * (1.-exp(-2.0*tau_mol_lay(:))) ELSEWHERE ! This must never happend, but just in case, to avoid div. by 0 pmol(:,k) = beta_mol(:,k) * EXP(-2.0*tau_mol(:,k+1)) END WHERE END DO ! Total signal (molecular + particules): ! ! ! For performance reason on vector computers, the 2 following lines should not be used ! and should be replace by the later one. ! betatot(:,:) = beta_mol(:,:) + sum(kp_part*alpha_part,dim=3) ! tautot(:,:) = tau_mol(:,:) + sum(tau_part,dim=3) betatot(:,:) = beta_mol(:,:) tautot(:,:) = tau_mol(:,:) DO i = 1, npart betatot(:,:) = betatot(:,:) + kp_part(:,:,i)*alpha_part(:,:,i) tautot(:,:) = tautot(:,:) + tau_part(:,:,i) ENDDO ! i ! ! Upper layer pnorm(:,nlev) = betatot(:,nlev) / (2.*tautot(:,nlev)) & & * (1.-exp(-2.0*tautot(:,nlev))) ! Other layers DO k= nlev-1, 1, -1 tautot_lay(:) = tautot(:,k)-tautot(:,k+1) ! optical thickness of layer k WHERE (tautot_lay(:).GT.0.) pnorm(:,k) = betatot(:,k) * EXP(-2.0*tautot(:,k+1)) / (2.*tautot_lay(:)) & & * (1.-EXP(-2.0*tautot_lay(:))) ELSEWHERE ! This must never happend, but just in case, to avoid div. by 0 pnorm(:,k) = betatot(:,k) * EXP(-2.0*tautot(:,k+1)) END WHERE END DO !------------------------------------------------------------ !---- 4.2 Ice/Liq Backscatter signal: !------------------------------------------------------------ ! Contribution of the molecular to beta betatot_ice(:,:) = beta_mol(:,:) betatot_liq(:,:) = beta_mol(:,:) tautot_ice(:,:) = tau_mol(:,:) tautot_liq(:,:) = tau_mol(:,:) DO i = 2, npart,2 betatot_ice(:,:) = betatot_ice(:,:)+ kp_part(:,:,i)*alpha_part(:,:,i) tautot_ice(:,:) = tautot_ice(:,:) + tau_part(:,:,i) ENDDO ! i DO i = 1, npart,2 betatot_liq(:,:) = betatot_liq(:,:)+ kp_part(:,:,i)*alpha_part(:,:,i) tautot_liq(:,:) = tautot_liq(:,:) + tau_part(:,:,i) ENDDO ! i ! Computation of the ice and liquid lidar backscattered signal (ATBice and ATBliq) ! Ice only ! Upper layer pnorm_ice(:,nlev) = betatot_ice(:,nlev) / (2.*tautot_ice(:,nlev)) & & * (1.-exp(-2.0*tautot_ice(:,nlev))) DO k= nlev-1, 1, -1 tautot_lay_ice(:) = tautot_ice(:,k)-tautot_ice(:,k+1) WHERE (tautot_lay_ice(:).GT.0.) pnorm_ice(:,k)=betatot_ice(:,k)*EXP(-2.0*tautot_ice(:,k+1))/(2.*tautot_lay_ice(:)) & & * (1.-EXP(-2.0*tautot_lay_ice(:))) ELSEWHERE pnorm_ice(:,k)=betatot_ice(:,k)*EXP(-2.0*tautot_ice(:,k+1)) END WHERE ENDDO ! Liquid only ! Upper layer pnorm_liq(:,nlev) = betatot_liq(:,nlev) / (2.*tautot_liq(:,nlev)) & & * (1.-exp(-2.0*tautot_liq(:,nlev))) DO k= nlev-1, 1, -1 tautot_lay_liq(:) = tautot_liq(:,k)-tautot_liq(:,k+1) WHERE (tautot_lay_liq(:).GT.0.) pnorm_liq(:,k)=betatot_liq(:,k)*EXP(-2.0*tautot_liq(:,k+1))/(2.*tautot_lay_liq(:)) & & * (1.-EXP(-2.0*tautot_lay_liq(:))) ELSEWHERE pnorm_liq(:,k)=betatot_liq(:,k)*EXP(-2.0*tautot_liq(:,k+1)) END WHERE ENDDO ! Computation of ATBperp,ice/liq from ATBice/liq including the multiple scattering ! contribution (Cesana and Chepfer 2013, JGR) ! ATBperp,ice = Alpha*ATBice ! ATBperp,liq = Beta*ATBliq^2 + Gamma*ATBliq DO k= nlev, 1, -1 pnorm_perp_ice(:,k) = Alpha * pnorm_ice(:,k) ! Ice particles pnorm_perp_liq(:,k) = 1000*Beta * pnorm_liq(:,k)**2 + Gamma * pnorm_liq(:,k) ! Liquid particles ENDDO ! Computation of beta_perp_ice/liq using the lidar equation ! Ice only ! Upper layer beta_perp_ice(:,nlev) = pnorm_perp_ice(:,nlev) * (2.*tautot_ice(:,nlev)) & & / (1.-exp(-2.0*tautot_ice(:,nlev))) DO k= nlev-1, 1, -1 tautot_lay_ice(:) = tautot_ice(:,k)-tautot_ice(:,k+1) WHERE (tautot_lay_ice(:).GT.0.) beta_perp_ice(:,k) = pnorm_perp_ice(:,k)/ EXP(-2.0*tautot_ice(:,k+1)) * (2.*tautot_lay_ice(:)) & & / (1.-exp(-2.0*tautot_lay_ice(:))) ELSEWHERE beta_perp_ice(:,k)=pnorm_perp_ice(:,k)/EXP(-2.0*tautot_ice(:,k+1)) END WHERE ENDDO ! Liquid only ! Upper layer beta_perp_liq(:,nlev) = pnorm_perp_liq(:,nlev) * (2.*tautot_liq(:,nlev)) & & / (1.-exp(-2.0*tautot_liq(:,nlev))) DO k= nlev-1, 1, -1 tautot_lay_liq(:) = tautot_liq(:,k)-tautot_liq(:,k+1) WHERE (tautot_lay_liq(:).GT.0.) beta_perp_liq(:,k) = pnorm_perp_liq(:,k)/ max(seuil,EXP(-2.0*tautot_liq(:,k+1))) & & * (2.*tautot_lay_liq(:)) / (1.-exp(-2.0*tautot_lay_liq(:))) ELSEWHERE beta_perp_liq(:,k)=pnorm_perp_liq(:,k)/EXP(-2.0*tautot_liq(:,k+1)) END WHERE ENDDO !------------------------------------------------------------ !---- 4.3 Perpendicular Backscatter signal: !------------------------------------------------------------ ! Computation of the total perpendicular lidar signal (ATBperp for liq+ice) ! Upper layer WHERE(tautot(:,nlev).GT.0) pnorm_perp_tot(:,nlev) = & (beta_perp_ice(:,nlev)+beta_perp_liq(:,nlev)-(beta_mol(:,nlev)/(1+1/0.0284))) / (2.*tautot(:,nlev)) & & * (1.-exp(-2.0*tautot(:,nlev))) ELSEWHERE pnorm_perp_tot(:,nlev) = 0. ENDWHERE ! Other layers DO k= nlev-1, 1, -1 tautot_lay(:) = tautot(:,k)-tautot(:,k+1) ! optical thickness of layer k ! The perpendicular component of the molecular backscattered signal (Betaperp) has been ! taken into account two times (once for liquid and once for ice). ! We remove one contribution using ! Betaperp=beta_mol(:,k)/(1+1/0.0284)) [bodhaine et al. 1999] in the following equations: WHERE (pnorm(:,k).eq.0) pnorm_perp_tot(:,k)=0. ELSEWHERE WHERE (tautot_lay(:).GT.0.) pnorm_perp_tot(:,k) = & (beta_perp_ice(:,k)+beta_perp_liq(:,k)-(beta_mol(:,k)/(1+1/0.0284))) * & EXP(-2.0*tautot(:,k+1)) / (2.*tautot_lay(:)) & & * (1.-EXP(-2.0*tautot_lay(:))) ELSEWHERE ! This must never happen, but just in case, to avoid div. by 0 pnorm_perp_tot(:,k) = & (beta_perp_ice(:,k)+beta_perp_liq(:,k)-(beta_mol(:,k)/(1+1/0.0284))) * & EXP(-2.0*tautot(:,k+1)) END WHERE ENDWHERE END DO !-------- End computation Lidar -------------------------- !--------------------------------------------------------- ! Parasol/Polder module ! ! Purpose : Compute reflectance for one particular viewing direction ! and 5 solar zenith angles (calculation valid only over ocean) ! --------------------------------------------------------- ! initialization: refl(:,:) = 0.0 ! activate parasol calculations: if (ok_parasol) then ! Optical thickness from TOA to surface tautot_S_liq = 0. tautot_S_ice = 0. tautot_S_liq(:) = tautot_S_liq(:) & + tau_part(:,1,1) + tau_part(:,1,3) tautot_S_ice(:) = tautot_S_ice(:) & + tau_part(:,1,2) + tau_part(:,1,4) call parasol(npoints,nrefl,undef & ,tautot_S_liq,tautot_S_ice & ,refl) endif ! ok_parasol END SUBROUTINE lidar_simulator ! !--------------------------------------------------------------------------------- ! SUBROUTINE parasol(npoints,nrefl,undef & ,tautot_S_liq,tautot_S_ice & ,refl) !--------------------------------------------------------------------------------- ! Purpose: To compute Parasol reflectance signal from model-simulated profiles ! of cloud water and cloud fraction in each sub-column of each model ! gridbox. ! ! ! December 2008, S. Bony, H. Chepfer and J-L. Dufresne : ! - optimization for vectorization ! ! Version 2.0 (October 2008) ! Version 2.1 (December 2008) !--------------------------------------------------------------------------------- IMPLICIT NONE ! inputs INTEGER npoints ! Number of horizontal gridpoints INTEGER nrefl ! Number of angles for which the reflectance ! is computed. Can not be greater then ntetas REAL undef ! Undefined value. Currently not used REAL tautot_S_liq(npoints) ! liquid water cloud optical thickness, ! integrated from TOA to surface REAL tautot_S_ice(npoints) ! same for ice water clouds only ! outputs REAL refl(npoints,nrefl) ! Parasol reflectances ! ! Local variables REAL tautot_S(npoints) ! cloud optical thickness, from TOA to surface REAL frac_taucol_liq(npoints), frac_taucol_ice(npoints) REAL pi ! look up table variables: INTEGER ny, it INTEGER ntetas, nbtau ! number of angle and of optical thickness ! of the look-up table PARAMETER (ntetas=5, nbtau=7) REAL aa(ntetas,nbtau-1), ab(ntetas,nbtau-1) REAL ba(ntetas,nbtau-1), bb(ntetas,nbtau-1) REAL tetas(ntetas),tau(nbtau) REAL r_norm(ntetas) REAL rlumA(ntetas,nbtau), rlumB(ntetas,nbtau) REAL rlumA_mod(npoints,5), rlumB_mod(npoints,5) DATA tau /0., 1., 5., 10., 20., 50., 100./ DATA tetas /0., 20., 40., 60., 80./ ! Look-up table for spherical liquid particles: DATA (rlumA(1,ny),ny=1,nbtau) /0.03, 0.090886, 0.283965, & 0.480587, 0.695235, 0.908229, 1.0 / DATA (rlumA(2,ny),ny=1,nbtau) /0.03, 0.072185, 0.252596, & 0.436401, 0.631352, 0.823924, 0.909013 / DATA (rlumA(3,ny),ny=1,nbtau) /0.03, 0.058410, 0.224707, & 0.367451, 0.509180, 0.648152, 0.709554 / DATA (rlumA(4,ny),ny=1,nbtau) /0.03, 0.052498, 0.175844, & 0.252916, 0.326551, 0.398581, 0.430405 / DATA (rlumA(5,ny),ny=1,nbtau) /0.03, 0.034730, 0.064488, & 0.081667, 0.098215, 0.114411, 0.121567 / ! Look-up table for ice particles: DATA (rlumB(1,ny),ny=1,nbtau) /0.03, 0.092170, 0.311941, & 0.511298, 0.712079 , 0.898243 , 0.976646 / DATA (rlumB(2,ny),ny=1,nbtau) /0.03, 0.087082, 0.304293, & 0.490879, 0.673565, 0.842026, 0.912966 / DATA (rlumB(3,ny),ny=1,nbtau) /0.03, 0.083325, 0.285193, & 0.430266, 0.563747, 0.685773, 0.737154 / DATA (rlumB(4,ny),ny=1,nbtau) /0.03, 0.084935, 0.233450, & 0.312280, 0.382376, 0.446371, 0.473317 / DATA (rlumB(5,ny),ny=1,nbtau) /0.03, 0.054157, 0.089911, & 0.107854, 0.124127, 0.139004, 0.145269 / !-------------------------------------------------------------------------------- ! Lum_norm=f(tetaS,tau_cloud) derived from adding-doubling calculations ! valid ONLY ABOVE OCEAN (albedo_sfce=5%) ! valid only in one viewing direction (theta_v=30�, phi_s-phi_v=320�) ! based on adding-doubling radiative transfer computation ! for tau values (0 to 100) and for tetas values (0 to 80) ! for 2 scattering phase functions: liquid spherical, ice non spherical IF ( nrefl.GT. ntetas ) THEN PRINT *,'Error in lidar_simulator, nrefl should be less then ',ntetas,' not',nrefl STOP ENDIF rlumA_mod=0 rlumB_mod=0 ! pi = ACOS(-1.0) r_norm(:)=1./ COS(pi/180.*tetas(:)) ! tautot_S_liq(:)=MAX(tautot_S_liq(:),tau(1)) tautot_S_ice(:)=MAX(tautot_S_ice(:),tau(1)) tautot_S(:) = tautot_S_ice(:) + tautot_S_liq(:) ! ! relative fraction of the opt. thick due to liquid or ice clouds WHERE (tautot_S(:) .GT. 0.) frac_taucol_liq(:) = tautot_S_liq(:) / tautot_S(:) frac_taucol_ice(:) = tautot_S_ice(:) / tautot_S(:) ELSEWHERE frac_taucol_liq(:) = 1. frac_taucol_ice(:) = 0. END WHERE tautot_S(:)=MIN(tautot_S(:),tau(nbtau)) ! ! Linear interpolation : DO ny=1,nbtau-1 ! microphysics A (liquid clouds) aA(:,ny) = (rlumA(:,ny+1)-rlumA(:,ny))/(tau(ny+1)-tau(ny)) bA(:,ny) = rlumA(:,ny) - aA(:,ny)*tau(ny) ! microphysics B (ice clouds) aB(:,ny) = (rlumB(:,ny+1)-rlumB(:,ny))/(tau(ny+1)-tau(ny)) bB(:,ny) = rlumB(:,ny) - aB(:,ny)*tau(ny) ENDDO ! DO it=1,ntetas DO ny=1,nbtau-1 WHERE (tautot_S(:).GE.tau(ny).AND.tautot_S(:).LE.tau(ny+1)) rlumA_mod(:,it) = aA(it,ny)*tautot_S(:) + bA(it,ny) rlumB_mod(:,it) = aB(it,ny)*tautot_S(:) + bB(it,ny) END WHERE END DO END DO ! DO it=1,ntetas refl(:,it) = frac_taucol_liq(:) * rlumA_mod(:,it) & + frac_taucol_ice(:) * rlumB_mod(:,it) ! normalized radiance -> reflectance: refl(:,it) = refl(:,it) * r_norm(it) ENDDO RETURN END SUBROUTINE parasol