| 1 | ! radiation_mcica_sw.F90 - Monte-Carlo Independent Column Approximation shortwave solver |
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| 2 | ! |
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| 3 | ! (C) Copyright 2015- ECMWF. |
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| 4 | ! |
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| 5 | ! This software is licensed under the terms of the Apache Licence Version 2.0 |
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| 6 | ! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0. |
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| 7 | ! |
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| 8 | ! In applying this licence, ECMWF does not waive the privileges and immunities |
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| 9 | ! granted to it by virtue of its status as an intergovernmental organisation |
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| 10 | ! nor does it submit to any jurisdiction. |
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| 11 | ! |
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| 12 | ! Author: Robin Hogan |
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| 13 | ! Email: r.j.hogan@ecmwf.int |
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| 14 | ! |
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| 15 | ! Modifications |
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| 16 | ! 2017-04-11 R. Hogan Receive albedos at g-points |
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| 17 | ! 2017-04-22 R. Hogan Store surface fluxes at all g-points |
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| 18 | ! 2017-10-23 R. Hogan Renamed single-character variables |
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| 19 | |
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| 20 | module radiation_mcica_sw |
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| 21 | |
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| 22 | public |
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| 23 | |
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| 24 | contains |
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| 25 | |
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| 26 | ! Provides elemental function "delta_eddington" |
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| 27 | #include "radiation_delta_eddington.h" |
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| 28 | |
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| 29 | !--------------------------------------------------------------------- |
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| 30 | ! Shortwave Monte Carlo Independent Column Approximation |
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| 31 | ! (McICA). This implementation performs a clear-sky and a cloudy-sky |
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| 32 | ! calculation, and then weights the two to get the all-sky fluxes |
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| 33 | ! according to the total cloud cover. This method reduces noise for |
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| 34 | ! low cloud cover situations, and exploits the clear-sky |
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| 35 | ! calculations that are usually performed for diagnostic purposes |
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| 36 | ! simultaneously. The cloud generator has been carefully written |
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| 37 | ! such that the stochastic cloud field satisfies the prescribed |
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| 38 | ! overlap parameter accounting for this weighting. |
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| 39 | subroutine solver_mcica_sw(nlev,istartcol,iendcol, & |
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| 40 | & config, single_level, cloud, & |
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| 41 | & od, ssa, g, od_cloud, ssa_cloud, g_cloud, & |
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| 42 | & albedo_direct, albedo_diffuse, incoming_sw, & |
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| 43 | & flux) |
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| 44 | |
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| 45 | use parkind1, only : jprb |
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| 46 | use yomhook, only : lhook, dr_hook |
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| 47 | |
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| 48 | use radiation_io, only : nulerr, radiation_abort |
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| 49 | use radiation_config, only : config_type |
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| 50 | use radiation_single_level, only : single_level_type |
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| 51 | use radiation_cloud, only : cloud_type |
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| 52 | use radiation_flux, only : flux_type |
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| 53 | use radiation_two_stream, only : calc_two_stream_gammas_sw, & |
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| 54 | & calc_reflectance_transmittance_sw |
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| 55 | use radiation_adding_ica_sw, only : adding_ica_sw |
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| 56 | use radiation_cloud_generator, only: cloud_generator |
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| 57 | |
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| 58 | implicit none |
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| 59 | |
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| 60 | ! Inputs |
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| 61 | integer, intent(in) :: nlev ! number of model levels |
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| 62 | integer, intent(in) :: istartcol, iendcol ! range of columns to process |
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| 63 | type(config_type), intent(in) :: config |
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| 64 | type(single_level_type), intent(in) :: single_level |
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| 65 | type(cloud_type), intent(in) :: cloud |
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| 66 | |
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| 67 | ! Gas and aerosol optical depth, single-scattering albedo and |
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| 68 | ! asymmetry factor at each shortwave g-point |
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| 69 | real(jprb), intent(in), dimension(config%n_g_sw, nlev, istartcol:iendcol) :: & |
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| 70 | & od, ssa, g |
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| 71 | |
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| 72 | ! Cloud and precipitation optical depth, single-scattering albedo and |
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| 73 | ! asymmetry factor in each shortwave band |
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| 74 | real(jprb), intent(in), dimension(config%n_bands_sw,nlev,istartcol:iendcol) :: & |
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| 75 | & od_cloud, ssa_cloud, g_cloud |
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| 76 | |
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| 77 | ! Direct and diffuse surface albedos, and the incoming shortwave |
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| 78 | ! flux into a plane perpendicular to the incoming radiation at |
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| 79 | ! top-of-atmosphere in each of the shortwave g points |
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| 80 | real(jprb), intent(in), dimension(config%n_g_sw,istartcol:iendcol) :: & |
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| 81 | & albedo_direct, albedo_diffuse, incoming_sw |
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| 82 | |
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| 83 | ! Output |
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| 84 | type(flux_type), intent(inout):: flux |
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| 85 | |
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| 86 | ! Local variables |
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| 87 | |
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| 88 | ! Cosine of solar zenith angle |
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| 89 | real(jprb) :: cos_sza |
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| 90 | |
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| 91 | ! Diffuse reflectance and transmittance for each layer in clear |
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| 92 | ! and all skies |
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| 93 | real(jprb), dimension(config%n_g_sw, nlev) :: ref_clear, trans_clear, reflectance, transmittance |
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| 94 | |
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| 95 | ! Fraction of direct beam scattered by a layer into the upwelling |
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| 96 | ! or downwelling diffuse streams, in clear and all skies |
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| 97 | real(jprb), dimension(config%n_g_sw, nlev) :: ref_dir_clear, trans_dir_diff_clear, ref_dir, trans_dir_diff |
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| 98 | |
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| 99 | ! Transmittance for the direct beam in clear and all skies |
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| 100 | real(jprb), dimension(config%n_g_sw, nlev) :: trans_dir_dir_clear, trans_dir_dir |
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| 101 | |
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| 102 | ! Fluxes per g point |
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| 103 | real(jprb), dimension(config%n_g_sw, nlev+1) :: flux_up, flux_dn_diffuse, flux_dn_direct |
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| 104 | |
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| 105 | ! Combined gas+aerosol+cloud optical depth, single scattering |
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| 106 | ! albedo and asymmetry factor |
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| 107 | real(jprb), dimension(config%n_g_sw) :: od_total, ssa_total, g_total |
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| 108 | |
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| 109 | ! Combined scattering optical depth |
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| 110 | real(jprb) :: scat_od |
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| 111 | |
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| 112 | ! Two-stream coefficients |
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| 113 | real(jprb), dimension(config%n_g_sw) :: gamma1, gamma2, gamma3 |
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| 114 | |
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| 115 | ! Optical depth scaling from the cloud generator, zero indicating |
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| 116 | ! clear skies |
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| 117 | real(jprb), dimension(config%n_g_sw,nlev) :: od_scaling |
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| 118 | |
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| 119 | ! Modified optical depth after McICA scaling to represent cloud |
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| 120 | ! inhomogeneity |
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| 121 | real(jprb), dimension(config%n_g_sw) :: od_cloud_new |
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| 122 | |
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| 123 | ! Total cloud cover output from the cloud generator |
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| 124 | real(jprb) :: total_cloud_cover |
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| 125 | |
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| 126 | ! Number of g points |
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| 127 | integer :: ng |
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| 128 | |
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| 129 | ! Loop indices for level, column and g point |
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| 130 | integer :: jlev, jcol, jg |
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| 131 | |
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| 132 | real(jprb) :: hook_handle |
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| 133 | |
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| 134 | if (lhook) call dr_hook('radiation_mcica_sw:solver_mcica_sw',0,hook_handle) |
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| 135 | |
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| 136 | if (.not. config%do_clear) then |
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| 137 | write(nulerr,'(a)') '*** Error: shortwave McICA requires clear-sky calculation to be performed' |
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| 138 | call radiation_abort() |
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| 139 | end if |
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| 140 | |
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| 141 | ng = config%n_g_sw |
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| 142 | |
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| 143 | ! Loop through columns |
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| 144 | do jcol = istartcol,iendcol |
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| 145 | ! Only perform calculation if sun above the horizon |
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| 146 | if (single_level%cos_sza(jcol) > 0.0_jprb) then |
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| 147 | cos_sza = single_level%cos_sza(jcol) |
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| 148 | |
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| 149 | ! Clear-sky calculation - first compute clear-sky reflectance, |
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| 150 | ! transmittance etc at each model level |
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| 151 | if (.not. config%do_sw_delta_scaling_with_gases) then |
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| 152 | ! Delta-Eddington scaling has already been performed to the |
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| 153 | ! aerosol part of od, ssa and g |
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| 154 | do jlev = 1,nlev |
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| 155 | call calc_two_stream_gammas_sw(ng, & |
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| 156 | & cos_sza, ssa(:,jlev,jcol), g(:,jlev,jcol), & |
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| 157 | & gamma1, gamma2, gamma3) |
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| 158 | call calc_reflectance_transmittance_sw(ng, & |
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| 159 | & cos_sza, od(:,jlev,jcol), ssa(:,jlev,jcol), & |
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| 160 | & gamma1, gamma2, gamma3, & |
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| 161 | & ref_clear(:,jlev), trans_clear(:,jlev), & |
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| 162 | & ref_dir_clear(:,jlev), trans_dir_diff_clear(:,jlev), & |
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| 163 | & trans_dir_dir_clear(:,jlev) ) |
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| 164 | end do |
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| 165 | else |
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| 166 | ! Apply delta-Eddington scaling to the aerosol-gas mixture |
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| 167 | do jlev = 1,nlev |
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| 168 | od_total = od(:,jlev,jcol) |
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| 169 | ssa_total = ssa(:,jlev,jcol) |
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| 170 | g_total = g(:,jlev,jcol) |
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| 171 | call delta_eddington(od_total, ssa_total, g_total) |
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| 172 | call calc_two_stream_gammas_sw(ng, & |
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| 173 | & cos_sza, ssa_total, g_total, & |
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| 174 | & gamma1, gamma2, gamma3) |
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| 175 | call calc_reflectance_transmittance_sw(ng, & |
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| 176 | & cos_sza, od_total, ssa_total, & |
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| 177 | & gamma1, gamma2, gamma3, & |
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| 178 | & ref_clear(:,jlev), trans_clear(:,jlev), & |
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| 179 | & ref_dir_clear(:,jlev), trans_dir_diff_clear(:,jlev), & |
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| 180 | & trans_dir_dir_clear(:,jlev) ) |
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| 181 | end do |
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| 182 | end if |
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| 183 | |
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| 184 | ! Use adding method to compute fluxes |
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| 185 | call adding_ica_sw(ng, nlev, incoming_sw(:,jcol), & |
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| 186 | & albedo_diffuse(:,jcol), albedo_direct(:,jcol), spread(cos_sza,1,ng), & |
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| 187 | & ref_clear, trans_clear, ref_dir_clear, trans_dir_diff_clear, & |
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| 188 | & trans_dir_dir_clear, flux_up, flux_dn_diffuse, flux_dn_direct) |
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| 189 | |
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| 190 | ! Sum over g-points to compute and save clear-sky broadband |
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| 191 | ! fluxes |
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| 192 | flux%sw_up_clear(jcol,:) = sum(flux_up,1) |
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| 193 | if (allocated(flux%sw_dn_direct_clear)) then |
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| 194 | flux%sw_dn_direct_clear(jcol,:) & |
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| 195 | & = sum(flux_dn_direct,1) |
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| 196 | flux%sw_dn_clear(jcol,:) = sum(flux_dn_diffuse,1) & |
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| 197 | & + flux%sw_dn_direct_clear(jcol,:) |
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| 198 | else |
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| 199 | flux%sw_dn_clear(jcol,:) = sum(flux_dn_diffuse,1) & |
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| 200 | & + sum(flux_dn_direct,1) |
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| 201 | end if |
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| 202 | ! Store spectral downwelling fluxes at surface |
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| 203 | flux%sw_dn_diffuse_surf_clear_g(:,jcol) = flux_dn_diffuse(:,nlev+1) |
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| 204 | flux%sw_dn_direct_surf_clear_g(:,jcol) = flux_dn_direct(:,nlev+1) |
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| 205 | |
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| 206 | ! Do cloudy-sky calculation |
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| 207 | call cloud_generator(ng, nlev, config%i_overlap_scheme, & |
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| 208 | & single_level%iseed(jcol), & |
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| 209 | & config%cloud_fraction_threshold, & |
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| 210 | & cloud%fraction(jcol,:), cloud%overlap_param(jcol,:), & |
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| 211 | & config%cloud_inhom_decorr_scaling, cloud%fractional_std(jcol,:), & |
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| 212 | & config%pdf_sampler, od_scaling, total_cloud_cover, & |
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| 213 | & use_beta_overlap=config%use_beta_overlap, & |
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| 214 | & use_vectorizable_generator=config%use_vectorizable_generator) |
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| 215 | |
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| 216 | ! Store total cloud cover |
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| 217 | flux%cloud_cover_sw(jcol) = total_cloud_cover |
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| 218 | |
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| 219 | if (total_cloud_cover >= config%cloud_fraction_threshold) then |
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| 220 | ! Total-sky calculation |
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| 221 | do jlev = 1,nlev |
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| 222 | ! Compute combined gas+aerosol+cloud optical properties |
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| 223 | if (cloud%fraction(jcol,jlev) >= config%cloud_fraction_threshold) then |
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| 224 | do jg = 1,ng |
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| 225 | od_cloud_new(jg) = od_scaling(jg,jlev) & |
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| 226 | & * od_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) |
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| 227 | od_total(jg) = od(jg,jlev,jcol) + od_cloud_new(jg) |
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| 228 | ssa_total(jg) = 0.0_jprb |
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| 229 | g_total(jg) = 0.0_jprb |
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| 230 | |
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| 231 | ! In single precision we need to protect against the |
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| 232 | ! case that od_total > 0.0 and ssa_total > 0.0 but |
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| 233 | ! od_total*ssa_total == 0 due to underflow |
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| 234 | if (od_total(jg) > 0.0_jprb) then |
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| 235 | scat_od = ssa(jg,jlev,jcol)*od(jg,jlev,jcol) & |
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| 236 | & + ssa_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & |
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| 237 | & * od_cloud_new(jg) |
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| 238 | ssa_total(jg) = scat_od / od_total(jg) |
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| 239 | if (scat_od > 0.0_jprb) then |
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| 240 | g_total(jg) = (g(jg,jlev,jcol)*ssa(jg,jlev,jcol)*od(jg,jlev,jcol) & |
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| 241 | & + g_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & |
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| 242 | & * ssa_cloud(config%i_band_from_reordered_g_sw(jg),jlev,jcol) & |
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| 243 | & * od_cloud_new(jg)) & |
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| 244 | & / scat_od |
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| 245 | end if |
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| 246 | end if |
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| 247 | end do |
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| 248 | |
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| 249 | ! Apply delta-Eddington scaling to the cloud-aerosol-gas |
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| 250 | ! mixture |
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| 251 | if (config%do_sw_delta_scaling_with_gases) then |
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| 252 | call delta_eddington(od_total, ssa_total, g_total) |
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| 253 | end if |
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| 254 | |
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| 255 | ! Compute cloudy-sky reflectance, transmittance etc at |
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| 256 | ! each model level |
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| 257 | call calc_two_stream_gammas_sw(ng, & |
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| 258 | & cos_sza, ssa_total, g_total, & |
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| 259 | & gamma1, gamma2, gamma3) |
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| 260 | |
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| 261 | call calc_reflectance_transmittance_sw(ng, & |
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| 262 | & cos_sza, od_total, ssa_total, & |
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| 263 | & gamma1, gamma2, gamma3, & |
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| 264 | & reflectance(:,jlev), transmittance(:,jlev), & |
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| 265 | & ref_dir(:,jlev), trans_dir_diff(:,jlev), & |
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| 266 | & trans_dir_dir(:,jlev) ) |
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| 267 | |
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| 268 | else |
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| 269 | ! Clear-sky layer: copy over clear-sky values |
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| 270 | reflectance(:,jlev) = ref_clear(:,jlev) |
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| 271 | transmittance(:,jlev) = trans_clear(:,jlev) |
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| 272 | ref_dir(:,jlev) = ref_dir_clear(:,jlev) |
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| 273 | trans_dir_diff(:,jlev) = trans_dir_diff_clear(:,jlev) |
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| 274 | trans_dir_dir(:,jlev) = trans_dir_dir_clear(:,jlev) |
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| 275 | end if |
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| 276 | end do |
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| 277 | |
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| 278 | ! Use adding method to compute fluxes for an overcast sky |
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| 279 | call adding_ica_sw(ng, nlev, incoming_sw(:,jcol), & |
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| 280 | & albedo_diffuse(:,jcol), albedo_direct(:,jcol), spread(cos_sza,1,ng), & |
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| 281 | & reflectance, transmittance, ref_dir, trans_dir_diff, & |
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| 282 | & trans_dir_dir, flux_up, flux_dn_diffuse, flux_dn_direct) |
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| 283 | |
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| 284 | ! Store overcast broadband fluxes |
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| 285 | flux%sw_up(jcol,:) = sum(flux_up,1) |
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| 286 | if (allocated(flux%sw_dn_direct)) then |
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| 287 | flux%sw_dn_direct(jcol,:) = sum(flux_dn_direct,1) |
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| 288 | flux%sw_dn(jcol,:) = sum(flux_dn_diffuse,1) & |
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| 289 | & + flux%sw_dn_direct(jcol,:) |
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| 290 | else |
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| 291 | flux%sw_dn(jcol,:) = sum(flux_dn_diffuse,1) & |
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| 292 | & + sum(flux_dn_direct,1) |
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| 293 | end if |
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| 294 | |
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| 295 | ! Cloudy flux profiles currently assume completely overcast |
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| 296 | ! skies; perform weighted average with clear-sky profile |
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| 297 | flux%sw_up(jcol,:) = total_cloud_cover *flux%sw_up(jcol,:) & |
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| 298 | & + (1.0_jprb - total_cloud_cover)*flux%sw_up_clear(jcol,:) |
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| 299 | flux%sw_dn(jcol,:) = total_cloud_cover *flux%sw_dn(jcol,:) & |
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| 300 | & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_clear(jcol,:) |
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| 301 | if (allocated(flux%sw_dn_direct)) then |
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| 302 | flux%sw_dn_direct(jcol,:) = total_cloud_cover *flux%sw_dn_direct(jcol,:) & |
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| 303 | & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_direct_clear(jcol,:) |
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| 304 | end if |
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| 305 | ! Likewise for surface spectral fluxes |
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| 306 | flux%sw_dn_diffuse_surf_g(:,jcol) = flux_dn_diffuse(:,nlev+1) |
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| 307 | flux%sw_dn_direct_surf_g(:,jcol) = flux_dn_direct(:,nlev+1) |
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| 308 | flux%sw_dn_diffuse_surf_g(:,jcol) = total_cloud_cover *flux%sw_dn_diffuse_surf_g(:,jcol) & |
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| 309 | & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_diffuse_surf_clear_g(:,jcol) |
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| 310 | flux%sw_dn_direct_surf_g(:,jcol) = total_cloud_cover *flux%sw_dn_direct_surf_g(:,jcol) & |
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| 311 | & + (1.0_jprb - total_cloud_cover)*flux%sw_dn_direct_surf_clear_g(:,jcol) |
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| 312 | |
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| 313 | else |
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| 314 | ! No cloud in profile and clear-sky fluxes already |
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| 315 | ! calculated: copy them over |
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| 316 | flux%sw_up(jcol,:) = flux%sw_up_clear(jcol,:) |
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| 317 | flux%sw_dn(jcol,:) = flux%sw_dn_clear(jcol,:) |
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| 318 | if (allocated(flux%sw_dn_direct)) then |
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| 319 | flux%sw_dn_direct(jcol,:) = flux%sw_dn_direct_clear(jcol,:) |
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| 320 | end if |
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| 321 | flux%sw_dn_diffuse_surf_g(:,jcol) = flux%sw_dn_diffuse_surf_clear_g(:,jcol) |
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| 322 | flux%sw_dn_direct_surf_g(:,jcol) = flux%sw_dn_direct_surf_clear_g(:,jcol) |
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| 323 | |
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| 324 | end if ! Cloud is present in profile |
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| 325 | |
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| 326 | else |
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| 327 | ! Set fluxes to zero if sun is below the horizon |
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| 328 | flux%sw_up(jcol,:) = 0.0_jprb |
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| 329 | flux%sw_dn(jcol,:) = 0.0_jprb |
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| 330 | if (allocated(flux%sw_dn_direct)) then |
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| 331 | flux%sw_dn_direct(jcol,:) = 0.0_jprb |
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| 332 | end if |
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| 333 | flux%sw_up_clear(jcol,:) = 0.0_jprb |
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| 334 | flux%sw_dn_clear(jcol,:) = 0.0_jprb |
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| 335 | if (allocated(flux%sw_dn_direct_clear)) then |
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| 336 | flux%sw_dn_direct_clear(jcol,:) = 0.0_jprb |
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| 337 | end if |
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| 338 | flux%sw_dn_diffuse_surf_g(:,jcol) = 0.0_jprb |
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| 339 | flux%sw_dn_direct_surf_g(:,jcol) = 0.0_jprb |
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| 340 | flux%sw_dn_diffuse_surf_clear_g(:,jcol) = 0.0_jprb |
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| 341 | flux%sw_dn_direct_surf_clear_g(:,jcol) = 0.0_jprb |
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| 342 | end if ! Sun above horizon |
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| 343 | |
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| 344 | end do ! Loop over columns |
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| 345 | |
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| 346 | if (lhook) call dr_hook('radiation_mcica_sw:solver_mcica_sw',1,hook_handle) |
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| 347 | |
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| 348 | end subroutine solver_mcica_sw |
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| 349 | |
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| 350 | end module radiation_mcica_sw |
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