! radiation_homogeneous_lw.F90 - Longwave homogeneous-column (no cloud fraction) solver ! ! (C) Copyright 2016- 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 emission/albedo rather than planck/emissivity ! 2017-04-22 R. Hogan Store surface fluxes at all g-points ! 2017-10-23 R. Hogan Renamed single-character variables ! 2019-01-14 R. Hogan Save spectral flux profile if required module radiation_homogeneous_lw public contains !--------------------------------------------------------------------- ! Longwave homogeneous solver, in which clouds are assumed to fill ! the gridbox horizontally subroutine solver_homogeneous_lw(nlev,istartcol,iendcol, & & config, cloud, & & od, ssa, g, od_cloud, ssa_cloud, g_cloud, planck_hl, & & emission, albedo, & & flux) use parkind1, only : jprb use yomhook, only : lhook, dr_hook, jphook use radiation_config, only : config_type use radiation_cloud, only : cloud_type use radiation_flux, only : flux_type, indexed_sum_profile use radiation_two_stream, only : calc_two_stream_gammas_lw, & & calc_reflectance_transmittance_lw, & & calc_no_scattering_transmittance_lw use radiation_adding_ica_lw, only : adding_ica_lw, calc_fluxes_no_scattering_lw use radiation_lw_derivatives, only : calc_lw_derivatives_ica 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(cloud_type), intent(in) :: cloud ! Gas and aerosol optical depth, single-scattering albedo and ! asymmetry factor at each longwave g-point real(jprb), intent(in), dimension(config%n_g_lw, nlev, istartcol:iendcol) :: & & od real(jprb), intent(in), dimension(config%n_g_lw_if_scattering, nlev, istartcol:iendcol) :: & & ssa, g ! Cloud and precipitation optical depth, single-scattering albedo and ! asymmetry factor in each longwave band real(jprb), intent(in), dimension(config%n_bands_lw,nlev,istartcol:iendcol) :: & & od_cloud real(jprb), intent(in), dimension(config%n_bands_lw_if_scattering, & & nlev,istartcol:iendcol) :: ssa_cloud, g_cloud ! Planck function at each half-level and the surface real(jprb), intent(in), dimension(config%n_g_lw,nlev+1,istartcol:iendcol) :: & & planck_hl ! Emission (Planck*emissivity) and albedo (1-emissivity) at the ! surface at each longwave g-point real(jprb), intent(in), dimension(config%n_g_lw, istartcol:iendcol) & & :: emission, albedo ! Output type(flux_type), intent(inout):: flux ! Local variables ! Diffuse reflectance and transmittance for each layer in clear ! and all skies real(jprb), dimension(config%n_g_lw, nlev) :: reflectance, transmittance ! Emission by a layer into the upwelling or downwelling diffuse ! streams, in clear and all skies real(jprb), dimension(config%n_g_lw, nlev) :: source_up, source_dn ! Fluxes per g point real(jprb), dimension(config%n_g_lw, nlev+1) :: flux_up, flux_dn ! Combined gas+aerosol+cloud optical depth, single scattering ! albedo and asymmetry factor real(jprb), dimension(config%n_g_lw) :: od_total, ssa_total, g_total ! Two-stream coefficients real(jprb), dimension(config%n_g_lw) :: gamma1, gamma2 ! Optical depth of cloud in g-point space real(jprb), dimension(config%n_g_lw) :: od_cloud_g ! Is there any cloud in the profile? logical :: is_cloudy_profile ! Number of g points integer :: ng ! Loop indices for level and column integer :: jlev, jcol real(jphook) :: hook_handle if (lhook) call dr_hook('radiation_homogeneous_lw:solver_homogeneous_lw',0,hook_handle) ng = config%n_g_lw ! Loop through columns do jcol = istartcol,iendcol ! Is there any cloud in the profile? is_cloudy_profile = .false. do jlev = 1,nlev if (cloud%fraction(jcol,jlev) >= config%cloud_fraction_threshold) then is_cloudy_profile = .true. exit end if end do ! If clear-sky fluxes need to be computed then we first compute ! the reflectance and transmittance of all layers, neglecting ! clouds. If clear-sky fluxes are not required then we only do ! the clear-sky layers since these will be needed when we come ! to do the total-sky fluxes. do jlev = 1,nlev if (config%do_clear .or. cloud%fraction(jcol,jlev) & & < config%cloud_fraction_threshold) then if (config%do_lw_aerosol_scattering) then ! Scattering case: first compute clear-sky reflectance, ! transmittance etc at each model level ssa_total = ssa(:,jlev,jcol) g_total = g(:,jlev,jcol) call calc_two_stream_gammas_lw(ng, ssa_total, g_total, & & gamma1, gamma2) call calc_reflectance_transmittance_lw(ng, & & od(:,jlev,jcol), gamma1, gamma2, & & planck_hl(:,jlev,jcol), planck_hl(:,jlev+1,jcol), & & reflectance(:,jlev), transmittance(:,jlev), & & source_up(:,jlev), source_dn(:,jlev)) else ! Non-scattering case: use simpler functions for ! transmission and emission call calc_no_scattering_transmittance_lw(ng, od(:,jlev,jcol), & & planck_hl(:,jlev,jcol), planck_hl(:,jlev+1, jcol), & & transmittance(:,jlev), source_up(:,jlev), source_dn(:,jlev)) ! Ensure that clear-sky reflectance is zero since it may be ! used in cloudy-sky case reflectance(:,jlev) = 0.0_jprb end if end if end do if (config%do_clear) then if (config%do_lw_aerosol_scattering) then ! Then use adding method to compute fluxes call adding_ica_lw(ng, nlev, & & reflectance, transmittance, source_up, source_dn, & & emission(:,jcol), albedo(:,jcol), & & flux_up, flux_dn) else ! Simpler down-then-up method to compute fluxes call calc_fluxes_no_scattering_lw(ng, nlev, & & transmittance, source_up, source_dn, & & emission(:,jcol), albedo(:,jcol), & & flux_up, flux_dn) end if ! Sum over g-points to compute broadband fluxes flux%lw_up_clear(jcol,:) = sum(flux_up,1) flux%lw_dn_clear(jcol,:) = sum(flux_dn,1) ! Store surface spectral downwelling fluxes flux%lw_dn_surf_clear_g(:,jcol) = flux_dn(:,nlev+1) ! Save the spectral fluxes if required if (config%do_save_spectral_flux) then call indexed_sum_profile(flux_up, config%i_spec_from_reordered_g_lw, & & flux%lw_up_clear_band(:,jcol,:)) call indexed_sum_profile(flux_dn, config%i_spec_from_reordered_g_lw, & & flux%lw_dn_clear_band(:,jcol,:)) end if end if ! Do clear-sky calculations ! Now the total-sky calculation. If this is a clear profile and ! clear-sky fluxes have been calculated then we can simply copy ! over the clear-sky fluxes, otherwise we need to compute fluxes ! now. if (is_cloudy_profile .or. .not. config%do_clear) then do jlev = 1,nlev ! Compute combined gas+aerosol+cloud optical properties; ! note that for clear layers, the reflectance and ! transmittance have already been calculated if (cloud%fraction(jcol,jlev) >= config%cloud_fraction_threshold) then od_cloud_g = od_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) od_total = od(:,jlev,jcol) + od_cloud_g ssa_total = 0.0_jprb g_total = 0.0_jprb if (config%do_lw_cloud_scattering) then ! Scattering case: calculate reflectance and ! transmittance at each model level if (config%do_lw_aerosol_scattering) then where (od_total > 0.0_jprb) ssa_total = (ssa(:,jlev,jcol)*od(:,jlev,jcol) & & + ssa_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * od_cloud_g) & & / od_total end where where (ssa_total > 0.0_jprb .and. od_total > 0.0_jprb) g_total = (g(:,jlev,jcol)*ssa(:,jlev,jcol)*od(:,jlev,jcol) & & + g_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * ssa_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * od_cloud_g) & & / (ssa_total*od_total) end where else where (od_total > 0.0_jprb) ssa_total = ssa_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * od_cloud_g / od_total end where where (ssa_total > 0.0_jprb .and. od_total > 0.0_jprb) g_total = g_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * ssa_cloud(config%i_band_from_reordered_g_lw,jlev,jcol) & & * od_cloud_g / (ssa_total*od_total) end where end if ! Compute cloudy-sky reflectance, transmittance etc at ! each model level call calc_two_stream_gammas_lw(ng, ssa_total, g_total, & & gamma1, gamma2) call calc_reflectance_transmittance_lw(ng, & & od_total, gamma1, gamma2, & & planck_hl(:,jlev,jcol), planck_hl(:,jlev+1,jcol), & & reflectance(:,jlev), transmittance(:,jlev), & & source_up(:,jlev), source_dn(:,jlev)) else ! No-scattering case: use simpler functions for ! transmission and emission call calc_no_scattering_transmittance_lw(ng, od_total, & & planck_hl(:,jlev,jcol), planck_hl(:,jlev+1, jcol), & & transmittance(:,jlev), source_up(:,jlev), source_dn(:,jlev)) end if end if ! is cloudy layer end do if (config%do_lw_cloud_scattering) then ! Use adding method to compute fluxes for an overcast sky call adding_ica_lw(ng, nlev, reflectance, transmittance, source_up, source_dn, & & emission(:,jcol), albedo(:,jcol), & & flux_up, flux_dn) else ! Simpler down-then-up method to compute fluxes call calc_fluxes_no_scattering_lw(ng, nlev, & & transmittance, source_up, source_dn, emission(:,jcol), albedo(:,jcol), & & flux_up, flux_dn) end if ! Store overcast broadband fluxes flux%lw_up(jcol,:) = sum(flux_up,1) flux%lw_dn(jcol,:) = sum(flux_dn,1) ! Store surface spectral downwelling fluxes flux%lw_dn_surf_g(:,jcol) = flux_dn(:,nlev+1) ! Save the spectral fluxes if required if (config%do_save_spectral_flux) then call indexed_sum_profile(flux_up, config%i_spec_from_reordered_g_lw, & & flux%lw_up_band(:,jcol,:)) call indexed_sum_profile(flux_dn, config%i_spec_from_reordered_g_lw, & & flux%lw_dn_band(:,jcol,:)) end if else ! No cloud in profile and clear-sky fluxes already ! calculated: copy them over flux%lw_up(jcol,:) = flux%lw_up_clear(jcol,:) flux%lw_dn(jcol,:) = flux%lw_dn_clear(jcol,:) flux%lw_dn_surf_g(:,jcol) = flux%lw_dn_surf_clear_g(:,jcol) if (config%do_save_spectral_flux) then flux%lw_up_band(:,jcol,:) = flux%lw_up_clear_band(:,jcol,:) flux%lw_dn_band(:,jcol,:) = flux%lw_dn_clear_band(:,jcol,:) end if end if ! Compute the longwave derivatives needed by Hogan and Bozzo ! (2015) approximate radiation update scheme, using clear-sky ! transmittance if no clouds were present in the profile, ! all-sky transmittance otherwise if (config%do_lw_derivatives) then call calc_lw_derivatives_ica(ng, nlev, jcol, transmittance, flux_up(:,nlev+1), & & flux%lw_derivatives) end if end do if (lhook) call dr_hook('radiation_homogeneous_lw:solver_homogeneous_lw',1,hook_handle) end subroutine solver_homogeneous_lw end module radiation_homogeneous_lw