[4773] | 1 | ! radiation_ice_optics_baran2017.F90 - 2017 parameterization of Baran's ice optical properties |
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| 2 | ! |
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| 3 | ! (C) Copyright 2017- 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_ice_optics_baran2017 |
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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 | ! The number of ice coefficients depends on the parameterization |
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| 22 | integer, parameter :: NIceOpticsCoeffsBaran2017 = 9 |
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| 23 | integer, parameter :: NIceOpticsGeneralCoeffsBaran2017 = 5 |
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| 24 | |
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| 25 | contains |
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| 26 | |
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| 27 | |
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| 28 | !--------------------------------------------------------------------- |
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| 29 | ! Compute ice-particle scattering properties using a |
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| 30 | ! parameterization as a function of ice water mixing ratio and |
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| 31 | ! temperature |
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| 32 | subroutine calc_ice_optics_baran2017(nb, coeff_gen, coeff, ice_wp, & |
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| 33 | & qi, temperature, od, scat_od, g) |
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| 34 | |
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| 35 | use parkind1, only : jprb |
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| 36 | !use yomhook, only : lhook, dr_hook, jphook |
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| 37 | |
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| 38 | ! Number of bands |
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| 39 | integer, intent(in) :: nb |
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| 40 | ! General coefficients read from a data file |
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| 41 | real(jprb), intent(in) :: coeff_gen(:) |
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| 42 | ! Band-specific coefficients read from a data file |
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| 43 | real(jprb), intent(in) :: coeff(:,:) |
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| 44 | ! Ice water path (kg m-2) and mixing ratio (kg kg-1) |
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| 45 | real(jprb), intent(in) :: ice_wp, qi |
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| 46 | ! Temperature (K) |
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| 47 | real(jprb), intent(in) :: temperature |
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| 48 | ! Total optical depth, scattering optical depth and asymmetry factor |
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| 49 | real(jprb), intent(out) :: od(nb), scat_od(nb), g(nb) |
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| 50 | |
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| 51 | ! Modified ice mixing ratio, and the same raised to an appropriate power |
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| 52 | real(jprb) :: qi_mod, qi_mod_od, qi_mod_ssa, qi_mod_g |
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| 53 | |
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| 54 | !real(jphook) :: hook_handle |
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| 55 | |
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| 56 | !if (lhook) call dr_hook('radiation_ice_optics:calc_ice_optics_baran2017',0,hook_handle) |
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| 57 | |
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| 58 | qi_mod = qi * exp(coeff_gen(1)*(temperature-coeff_gen(2))) |
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| 59 | qi_mod_od = qi_mod ** coeff_gen(3) |
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| 60 | qi_mod_ssa = qi_mod ** coeff_gen(4) |
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| 61 | qi_mod_g = qi_mod ** coeff_gen(5) |
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| 62 | |
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| 63 | od = ice_wp * (coeff(1:nb,1) + coeff(1:nb,2)/(1.0_jprb+qi_mod_od *coeff(1:nb,3))) |
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| 64 | scat_od = od * (coeff(1:nb,4) + coeff(1:nb,5)/(1.0_jprb+qi_mod_ssa*coeff(1:nb,6))) |
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| 65 | g = coeff(1:nb,7) + coeff(1:nb,8)/(1.0_jprb+qi_mod_g *coeff(1:nb,9)) |
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| 66 | |
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| 67 | !if (lhook) call dr_hook('radiation_ice_optics:calc_ice_optics_baran2017',1,hook_handle) |
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| 68 | |
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| 69 | end subroutine calc_ice_optics_baran2017 |
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| 70 | |
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| 71 | end module radiation_ice_optics_baran2017 |
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