! radiation_cloudless_lw.F90 - Longwave homogeneous cloudless solver ! ! (C) Copyright 2019- 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 ! module radiation_cloudless_lw public :: solver_cloudless_lw contains !--------------------------------------------------------------------- ! Longwave homogeneous solver containing no clouds subroutine solver_cloudless_lw(nlev,istartcol,iendcol, & & config, od, ssa, g, planck_hl, emission, albedo, flux) use parkind1, only : jprb use yomhook, only : lhook, dr_hook use radiation_config, only : config_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 ! 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 ! 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 optical depth, single scattering albedo and asymmetry ! factor real(jprb), dimension(config%n_g_lw) :: ssa_total, g_total ! Two-stream coefficients real(jprb), dimension(config%n_g_lw) :: gamma1, gamma2 ! Number of g points integer :: ng ! Loop indices for level and column integer :: jlev, jcol real(jprb) :: hook_handle if (lhook) call dr_hook('radiation_cloudless_lw:solver_cloudless_lw',0,hook_handle) ng = config%n_g_lw ! Loop through columns do jcol = istartcol,iendcol ! Compute the reflectance and transmittance of all layers, ! neglecting clouds do jlev = 1,nlev 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 reflectance(:,jlev) = 0.0_jprb end if end do 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(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 if (config%do_clear) then ! Clear-sky calculations are equal to all-sky for this solver: ! copy fluxes over flux%lw_up_clear(jcol,:) = flux%lw_up(jcol,:) flux%lw_dn_clear(jcol,:) = flux%lw_dn(jcol,:) flux%lw_dn_surf_clear_g(:,jcol) = flux%lw_dn_surf_g(:,jcol) if (config%do_save_spectral_flux) then flux%lw_up_clear_band(:,jcol,:) = flux%lw_up_band(:,jcol,:) flux%lw_dn_clear_band(:,jcol,:) = flux%lw_dn_band(:,jcol,:) end if end if ! Compute the longwave derivatives needed by Hogan and Bozzo ! (2015) approximate radiation update scheme 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_cloudless_lw:solver_cloudless_lw',1,hook_handle) end subroutine solver_cloudless_lw end module radiation_cloudless_lw