! radiation_mcica_sw.F90 - Monte-Carlo Independent Column Approximation shortwave solver ! ! (C) Copyright 2015- ECMWF. ! ! This software is licensed under the terms of the Apache Licence Version 2.0 ! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0. ! ! In applying this licence, ECMWF does not waive the privileges and immunities ! granted to it by virtue of its status as an intergovernmental organisation ! nor does it submit to any jurisdiction. ! ! Author: Robin Hogan ! Email: r.j.hogan@ecmwf.int ! ! Modifications ! 2017-04-11 R. Hogan Receive albedos at g-points ! 2017-04-22 R. Hogan Store surface fluxes at all g-points ! 2017-10-23 R. Hogan Renamed single-character variables module radiation_mcica_sw public contains ! Provides elemental function "delta_eddington" #include "radiation_delta_eddington.h" !--------------------------------------------------------------------- ! Shortwave Monte Carlo Independent Column Approximation ! (McICA). This implementation performs a clear-sky and a cloudy-sky ! calculation, and then weights the two to get the all-sky fluxes ! according to the total cloud cover. This method reduces noise for ! low cloud cover situations, and exploits the clear-sky ! calculations that are usually performed for diagnostic purposes ! simultaneously. The cloud generator has been carefully written ! such that the stochastic cloud field satisfies the prescribed ! overlap parameter accounting for this weighting. subroutine solver_mcica_sw(nlev,istartcol,iendcol, & & config, single_level, cloud, & & od, ssa, g, od_cloud, ssa_cloud, g_cloud, & & albedo_direct, albedo_diffuse, incoming_sw, & & flux) use parkind1, only : jprb use yomhook, only : lhook, dr_hook use radiation_io, only : nulerr, radiation_abort use radiation_config, only : config_type use radiation_single_level, only : single_level_type use radiation_cloud, only : cloud_type use radiation_flux, only : flux_type use radiation_two_stream, only : calc_two_stream_gammas_sw, & & calc_reflectance_transmittance_sw use radiation_adding_ica_sw, only : adding_ica_sw use radiation_cloud_generator, only: cloud_generator implicit none ! Inputs integer, intent(in) :: nlev ! number of model levels integer, intent(in) :: istartcol, iendcol ! range of columns to process type(config_type), intent(in) :: config type(single_level_type), intent(in) :: single_level type(cloud_type), intent(in) :: cloud ! Gas and aerosol optical depth, single-scattering albedo and ! asymmetry factor at each shortwave g-point real(jprb), intent(in), dimension(config%n_g_sw, nlev, istartcol:iendcol) :: & & od, ssa, g ! Cloud and precipitation optical depth, single-scattering albedo and ! asymmetry factor in each shortwave band real(jprb), intent(in), dimension(config%n_bands_sw,nlev,istartcol:iendcol) :: & & od_cloud, ssa_cloud, g_cloud ! Direct and diffuse surface albedos, and the incoming shortwave ! flux into a plane perpendicular to the incoming radiation at ! top-of-atmosphere in each of the shortwave g points real(jprb), intent(in), dimension(config%n_g_sw,istartcol:iendcol) :: & & albedo_direct, albedo_diffuse, incoming_sw ! Output type(flux_type), intent(inout):: flux ! Local variables ! Cosine of solar zenith angle real(jprb) :: cos_sza ! Diffuse reflectance and transmittance for each layer in clear ! and all skies real(jprb), dimension(config%n_g_sw, nlev) :: ref_clear, trans_clear, reflectance, transmittance ! Fraction of direct beam scattered by a layer into the upwelling ! or downwelling diffuse streams, in clear and all skies real(jprb), dimension(config%n_g_sw, nlev) :: ref_dir_clear, trans_dir_diff_clear, ref_dir, trans_dir_diff ! Transmittance for the direct beam in clear and all skies real(jprb), dimension(config%n_g_sw, nlev) :: trans_dir_dir_clear, trans_dir_dir ! Fluxes per g point real(jprb), dimension(config%n_g_sw, nlev+1) :: flux_up, flux_dn_diffuse, flux_dn_direct ! Combined gas+aerosol+cloud optical depth, single scattering ! albedo and asymmetry factor real(jprb), dimension(config%n_g_sw) :: od_total, ssa_total, g_total ! Combined scattering optical depth real(jprb) :: scat_od ! Two-stream coefficients real(jprb), dimension(config%n_g_sw) :: gamma1, gamma2, gamma3 ! Optical depth scaling from the cloud generator, zero indicating ! clear skies real(jprb), dimension(config%n_g_sw,nlev) :: od_scaling ! Modified optical depth after McICA scaling to represent cloud ! inhomogeneity real(jprb), dimension(config%n_g_sw) :: od_cloud_new ! Total cloud cover output from the cloud generator real(jprb) :: total_cloud_cover ! Number of g points integer :: ng ! Loop indices for level, column and g point integer :: jlev, jcol, jg real(jprb) :: hook_handle if (lhook) call dr_hook('radiation_mcica_sw:solver_mcica_sw',0,hook_handle) if (.not. config%do_clear) then write(nulerr,'(a)') '*** Error: shortwave McICA requires clear-sky calculation to be performed' call radiation_abort() end if ng = config%n_g_sw ! Loop through columns do jcol = istartcol,iendcol ! Only perform calculation if sun above the horizon if (single_level%cos_sza(jcol) > 0.0_jprb) then cos_sza = single_level%cos_sza(jcol) ! Clear-sky calculation - first compute clear-sky reflectance, ! transmittance etc at each model level if (.not. config%do_sw_delta_scaling_with_gases) then ! Delta-Eddington scaling has already been performed to the ! aerosol part of od, ssa and g do jlev = 1,nlev call calc_two_stream_gammas_sw(ng, & & cos_sza, ssa(:,jlev,jcol), g(:,jlev,jcol), & & gamma1, gamma2, gamma3) call calc_reflectance_transmittance_sw(ng, & & cos_sza, od(:,jlev,jcol), ssa(:,jlev,jcol), & & gamma1, gamma2, gamma3, & & ref_clear(:,jlev), trans_clear(:,jlev), & & ref_dir_clear(:,jlev), trans_dir_diff_clear(:,jlev), & & trans_dir_dir_clear(:,jlev) ) end do else ! Apply delta-Eddington scaling to the aerosol-gas mixture do jlev = 1,nlev od_total = od(:,jlev,jcol) ssa_total = ssa(:,jlev,jcol) g_total = g(:,jlev,jcol) call delta_eddington(od_total, ssa_total, g_total) call calc_two_stream_gammas_sw(ng, & & cos_sza, ssa_total, g_total, & & gamma1, gamma2, gamma3) call calc_reflectance_transmittance_sw(ng, & & cos_sza, od_total, ssa_total, & & gamma1, gamma2, gamma3, & & ref_clear(:,jlev), trans_clear(:,jlev), & & ref_dir_clear(:,jlev), trans_dir_diff_clear(:,jlev), & & trans_dir_dir_clear(:,jlev) ) end do end if ! Use adding method to compute fluxes call adding_ica_sw(ng, nlev, incoming_sw(:,jcol), & & albedo_diffuse(:,jcol), albedo_direct(:,jcol), spread(cos_sza,1,ng), & & ref_clear, trans_clear, ref_dir_clear, trans_dir_diff_clear, & & trans_dir_dir_clear, flux_up, flux_dn_diffuse, flux_dn_direct) ! Sum over g-points to compute and save clear-sky broadband ! fluxes flux%sw_up_clear(jcol,:) = sum(flux_up,1) if (allocated(flux%sw_dn_direct_clear)) then flux%sw_dn_direct_clear(jcol,:) & & = sum(flux_dn_direct,1) flux%sw_dn_clear(jcol,:) = sum(flux_dn_diffuse,1) & & + flux%sw_dn_direct_clear(jcol,:) else flux%sw_dn_clear(jcol,:) = sum(flux_dn_diffuse,1) & & + sum(flux_dn_direct,1) end if ! Store spectral downwelling fluxes at surface flux%sw_dn_diffuse_surf_clear_g(:,jcol) = flux_dn_diffuse(:,nlev+1) flux%sw_dn_direct_surf_clear_g(:,jcol) = flux_dn_direct(:,nlev+1) ! Do cloudy-sky calculation call cloud_generator(ng, nlev, config%i_overlap_scheme, & & single_level%iseed(jcol), & & config%cloud_fraction_threshold, & & cloud%fraction(jcol,:), cloud%overlap_param(jcol,:), & & config%cloud_inhom_decorr_scaling, cloud%fractional_std(jcol,:), & & config%pdf_sampler, od_scaling, total_cloud_cover, & & use_beta_overlap=config%use_beta_overlap, & & use_vectorizable_generator=config%use_vectorizable_generator) ! Store total cloud cover flux%cloud_cover_sw(jcol) = total_cloud_cover if (total_cloud_cover >= config%cloud_fraction_threshold) then ! Total-sky calculation do jlev = 1,nlev ! Compute combined gas+aerosol+cloud optical properties if (cloud%fraction(jcol,jlev) >= config%cloud_fraction_threshold) then do jg = 1,ng od_cloud_new(jg) = od_scaling(jg,jlev) & & * od_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) od_total(jg) = od(jg,jlev,jcol) + od_cloud_new(jg) ssa_total(jg) = 0.0_jprb g_total(jg) = 0.0_jprb ! In single precision we need to protect against the ! case that od_total > 0.0 and ssa_total > 0.0 but ! od_total*ssa_total == 0 due to underflow if (od_total(jg) > 0.0_jprb) then scat_od = ssa(jg,jlev,jcol)*od(jg,jlev,jcol) & & + ssa_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & & * od_cloud_new(jg) ssa_total(jg) = scat_od / od_total(jg) if (scat_od > 0.0_jprb) then g_total(jg) = (g(jg,jlev,jcol)*ssa(jg,jlev,jcol)*od(jg,jlev,jcol) & & + g_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & & * ssa_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & & * od_cloud_new(jg)) & & / scat_od end if end if end do ! Apply delta-Eddington scaling to the cloud-aerosol-gas ! mixture if (config%do_sw_delta_scaling_with_gases) then call delta_eddington(od_total, ssa_total, g_total) end if ! Compute cloudy-sky reflectance, transmittance etc at ! each model level call calc_two_stream_gammas_sw(ng, & & cos_sza, ssa_total, g_total, & & gamma1, gamma2, gamma3) call calc_reflectance_transmittance_sw(ng, & & cos_sza, od_total, ssa_total, & & gamma1, gamma2, gamma3, & & reflectance(:,jlev), transmittance(:,jlev), & & ref_dir(:,jlev), trans_dir_diff(:,jlev), & & trans_dir_dir(:,jlev) ) else ! Clear-sky layer: copy over clear-sky values reflectance(:,jlev) = ref_clear(:,jlev) transmittance(:,jlev) = trans_clear(:,jlev) ref_dir(:,jlev) = ref_dir_clear(:,jlev) trans_dir_diff(:,jlev) = trans_dir_diff_clear(:,jlev) trans_dir_dir(:,jlev) = trans_dir_dir_clear(:,jlev) end if end do ! Use adding method to compute fluxes for an overcast sky call adding_ica_sw(ng, nlev, incoming_sw(:,jcol), & & albedo_diffuse(:,jcol), albedo_direct(:,jcol), spread(cos_sza,1,ng), & & reflectance, transmittance, ref_dir, trans_dir_diff, & & trans_dir_dir, flux_up, flux_dn_diffuse, flux_dn_direct) ! Store overcast broadband fluxes flux%sw_up(jcol,:) = sum(flux_up,1) if (allocated(flux%sw_dn_direct)) then flux%sw_dn_direct(jcol,:) = sum(flux_dn_direct,1) flux%sw_dn(jcol,:) = sum(flux_dn_diffuse,1) & & + flux%sw_dn_direct(jcol,:) else flux%sw_dn(jcol,:) = sum(flux_dn_diffuse,1) & & + sum(flux_dn_direct,1) end if ! Cloudy flux profiles currently assume completely overcast ! skies; perform weighted average with clear-sky profile flux%sw_up(jcol,:) = total_cloud_cover *flux%sw_up(jcol,:) & & + (1.0_jprb - total_cloud_cover)*flux%sw_up_clear(jcol,:) flux%sw_dn(jcol,:) = total_cloud_cover *flux%sw_dn(jcol,:) & & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_clear(jcol,:) if (allocated(flux%sw_dn_direct)) then flux%sw_dn_direct(jcol,:) = total_cloud_cover *flux%sw_dn_direct(jcol,:) & & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_direct_clear(jcol,:) end if ! Likewise for surface spectral fluxes flux%sw_dn_diffuse_surf_g(:,jcol) = flux_dn_diffuse(:,nlev+1) flux%sw_dn_direct_surf_g(:,jcol) = flux_dn_direct(:,nlev+1) flux%sw_dn_diffuse_surf_g(:,jcol) = total_cloud_cover *flux%sw_dn_diffuse_surf_g(:,jcol) & & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_diffuse_surf_clear_g(:,jcol) flux%sw_dn_direct_surf_g(:,jcol) = total_cloud_cover *flux%sw_dn_direct_surf_g(:,jcol) & & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_direct_surf_clear_g(:,jcol) else ! No cloud in profile and clear-sky fluxes already ! calculated: copy them over flux%sw_up(jcol,:) = flux%sw_up_clear(jcol,:) flux%sw_dn(jcol,:) = flux%sw_dn_clear(jcol,:) if (allocated(flux%sw_dn_direct)) then flux%sw_dn_direct(jcol,:) = flux%sw_dn_direct_clear(jcol,:) end if flux%sw_dn_diffuse_surf_g(:,jcol) = flux%sw_dn_diffuse_surf_clear_g(:,jcol) flux%sw_dn_direct_surf_g(:,jcol) = flux%sw_dn_direct_surf_clear_g(:,jcol) end if ! Cloud is present in profile else ! Set fluxes to zero if sun is below the horizon flux%sw_up(jcol,:) = 0.0_jprb flux%sw_dn(jcol,:) = 0.0_jprb if (allocated(flux%sw_dn_direct)) then flux%sw_dn_direct(jcol,:) = 0.0_jprb end if flux%sw_up_clear(jcol,:) = 0.0_jprb flux%sw_dn_clear(jcol,:) = 0.0_jprb if (allocated(flux%sw_dn_direct_clear)) then flux%sw_dn_direct_clear(jcol,:) = 0.0_jprb end if flux%sw_dn_diffuse_surf_g(:,jcol) = 0.0_jprb flux%sw_dn_direct_surf_g(:,jcol) = 0.0_jprb flux%sw_dn_diffuse_surf_clear_g(:,jcol) = 0.0_jprb flux%sw_dn_direct_surf_clear_g(:,jcol) = 0.0_jprb end if ! Sun above horizon end do ! Loop over columns if (lhook) call dr_hook('radiation_mcica_sw:solver_mcica_sw',1,hook_handle) end subroutine solver_mcica_sw end module radiation_mcica_sw