[3880] | 1 | ! radiation_liquid_optics_slingo.F90 - Slingo SW & Lindner-Li LW parameterization of liquid droplet optics |
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| 2 | ! |
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| 3 | ! (C) Copyright 2016- 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 | |
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| 16 | module radiation_liquid_optics_slingo |
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| 17 | |
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| 18 | implicit none |
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| 19 | public |
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| 20 | |
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| 21 | integer, parameter :: NLiqOpticsCoeffsSlingoSW = 6 |
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| 22 | integer, parameter :: NLiqOpticsCoeffsLindnerLiLW = 13 |
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| 23 | |
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| 24 | contains |
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| 25 | |
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| 26 | !--------------------------------------------------------------------- |
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| 27 | ! Compute liquid-droplet scattering properties in the shortwave from |
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| 28 | ! Slingo (1989). WARNING: this parameterization is known not to be |
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| 29 | ! very accurate: see Nielsen et al. (GMD 2014). |
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| 30 | subroutine calc_liq_optics_slingo(nb, coeff, lwp, re, od, scat_od, g) |
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| 31 | |
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| 32 | use parkind1, only : jprb |
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| 33 | !use yomhook, only : lhook, dr_hook |
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| 34 | |
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| 35 | ! Number of bands |
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| 36 | integer, intent(in) :: nb |
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| 37 | ! Coefficients read from a data file |
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| 38 | real(jprb), intent(in) :: coeff(:,:) |
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| 39 | ! Liquid water path (kg m-2) and effective radius (m) |
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| 40 | real(jprb), intent(in) :: lwp, re |
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| 41 | ! Total optical depth, scattering optical depth and asymmetry factor |
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| 42 | real(jprb), intent(out) :: od(nb), scat_od(nb), g(nb) |
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| 43 | |
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| 44 | ! Liquid water path in g m-2 |
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| 45 | real(jprb) :: lwp_gm_2 |
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| 46 | ! Effective radius in microns, and its inverse |
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| 47 | real(jprb) :: re_um, inv_re_um |
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| 48 | |
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| 49 | !real(jprb) :: hook_handle |
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| 50 | |
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| 51 | !if (lhook) call dr_hook('radiation_liquid_optics_slingo:calc_liq_optics_slingo',0,hook_handle) |
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| 52 | |
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| 53 | lwp_gm_2 = lwp * 1000.0_jprb |
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| 54 | ! Range of validity reported by Slingo (1989): 4.2-16.6 microns |
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| 55 | re_um = min(max(4.2_jprb, re * 1.0e6_jprb), 16.6_jprb) |
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| 56 | inv_re_um = 1.0_jprb / re_um |
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| 57 | |
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| 58 | od = lwp_gm_2 * (coeff(1:nb,1) + inv_re_um*coeff(1:nb,2)) |
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| 59 | scat_od = od * (1.0_jprb - coeff(1:nb,3) - re_um*coeff(1:nb,4)) |
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| 60 | g = coeff(1:nb,5) + re_um*coeff(1:nb,6) |
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| 61 | |
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| 62 | !if (lhook) call dr_hook('radiation_liquid_optics_slingo:calc_liq_optics_slingo',1,hook_handle) |
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| 63 | |
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| 64 | end subroutine calc_liq_optics_slingo |
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| 65 | |
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| 66 | |
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| 67 | !--------------------------------------------------------------------- |
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| 68 | ! Compute liquid-droplet scattering properties in the longwave from |
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| 69 | ! Lindner & Li (2000) |
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| 70 | subroutine calc_liq_optics_lindner_li(nb, coeff, lwp, re, od, scat_od, g) |
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| 71 | |
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| 72 | use parkind1, only : jprb |
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| 73 | use yomhook, only : lhook, dr_hook |
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| 74 | |
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| 75 | ! Number of bands |
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| 76 | integer, intent(in) :: nb |
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| 77 | ! Coefficients read from a data file |
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| 78 | real(jprb), intent(in) :: coeff(:,:) |
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| 79 | ! Liquid water path (kg m-2) and effective radius (m) |
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| 80 | real(jprb), intent(in) :: lwp, re |
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| 81 | ! Total optical depth, scattering optical depth and asymmetry factor |
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| 82 | real(jprb), intent(out) :: od(nb), scat_od(nb), g(nb) |
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| 83 | |
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| 84 | ! Liquid water path in g m-2 |
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| 85 | real(jprb) :: lwp_gm_2 |
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| 86 | ! Effective radius in microns, and its inverse |
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| 87 | real(jprb) :: re_um, inv_re_um |
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| 88 | |
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| 89 | real(jprb) :: hook_handle |
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| 90 | |
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| 91 | if (lhook) call dr_hook('radiation_liquid_optics_slingo:calc_liq_optics_lindner_li',0,hook_handle) |
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| 92 | |
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| 93 | lwp_gm_2 = lwp * 1000.0_jprb |
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| 94 | ! Range of validity reported by Lindner and Li (2000): 2-40 microns |
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| 95 | re_um = min(max(2.0_jprb, re * 1.0e6_jprb), 40.0_jprb) |
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| 96 | inv_re_um = 1.0_jprb / re_um |
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| 97 | |
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| 98 | od = lwp_gm_2 * (coeff(1:nb,1) + re_um*coeff(1:nb,2) + inv_re_um*(coeff(1:nb,3) & |
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| 99 | & + inv_re_um*(coeff(1:nb,4) + inv_re_um*coeff(1:nb,5)))) |
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| 100 | scat_od = od * (1.0_jprb - (coeff(1:nb,6) + inv_re_um*coeff(1:nb,7) & |
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| 101 | & + re_um*(coeff(1:nb,8) + re_um*coeff(1:nb,9)))) |
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| 102 | g = coeff(1:nb,10) + inv_re_um*coeff(1:nb,11) & |
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| 103 | & + re_um*(coeff(1:nb,12) + re_um*coeff(1:nb,13)) |
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| 104 | |
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| 105 | if (lhook) call dr_hook('radiation_liquid_optics_slingo:calc_liq_optics_lindner_li',1,hook_handle) |
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| 106 | |
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| 107 | end subroutine calc_liq_optics_lindner_li |
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| 108 | |
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| 109 | end module radiation_liquid_optics_slingo |
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