| 1 | ! radiation_ice_optics_baran2016.F90 - Baran et al. (2016) scheme for ice optical properties |
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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_ice_optics_baran2016 |
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| 17 | |
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| 18 | implicit none |
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| 19 | |
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| 20 | ! The number of ice coefficients depends on the parameterization |
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| 21 | integer, parameter :: NIceOpticsCoeffsBaran2016 = 5 |
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| 22 | |
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| 23 | contains |
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| 24 | |
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| 25 | |
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| 26 | !--------------------------------------------------------------------- |
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| 27 | ! Compute ice-particle scattering properties using a |
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| 28 | ! parameterization as a function of ice water mixing ratio and |
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| 29 | ! temperature |
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| 30 | subroutine calc_ice_optics_baran2016(nb, coeff, ice_wp, & |
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| 31 | & qi, temperature, od, scat_od, g) |
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| 32 | |
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| 33 | use parkind1, only : jprb |
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| 34 | !use yomhook, only : lhook, dr_hook, jphook |
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| 35 | |
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| 36 | ! Number of bands |
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| 37 | integer, intent(in) :: nb |
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| 38 | ! Coefficients read from a data file |
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| 39 | real(jprb), intent(in) :: coeff(:,:) |
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| 40 | ! Ice water path (kg m-2) and mixing ratio (kg kg-1) |
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| 41 | real(jprb), intent(in) :: ice_wp, qi |
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| 42 | ! Temperature (K) |
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| 43 | real(jprb), intent(in) :: temperature |
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| 44 | ! Total optical depth, scattering optical depth and asymmetry factor |
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| 45 | real(jprb), intent(out) :: od(nb), scat_od(nb), g(nb) |
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| 46 | |
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| 47 | ! Powers of temperature, some multiplied by qi |
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| 48 | real(jprb) :: qi_T, T2, qi_over_T4 |
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| 49 | |
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| 50 | !real(jphook) :: hook_handle |
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| 51 | |
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| 52 | !if (lhook) call dr_hook('radiation_ice_optics:calc_ice_optics_baran2016',0,hook_handle) |
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| 53 | |
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| 54 | T2 = temperature * temperature |
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| 55 | |
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| 56 | if (qi < 1.0e-3_jprb) then |
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| 57 | qi_T = qi * temperature |
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| 58 | qi_over_T4 = 1.0_jprb / (T2 * T2) |
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| 59 | else |
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| 60 | qi_T = 1.0e-3_jprb * temperature |
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| 61 | qi_over_T4 = 1.0_jprb / (T2 * T2) |
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| 62 | end if |
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| 63 | |
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| 64 | od = ice_wp * coeff(1:nb,1) * qi_over_T4 |
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| 65 | scat_od = od * (coeff(1:nb,2) + coeff(1:nb,3) * qi_T) |
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| 66 | g = coeff(1:nb,4) + coeff(1:nb,5) * qi_T |
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| 67 | |
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| 68 | !if (lhook) call dr_hook('radiation_ice_optics:calc_ice_optics_baran2016',1,hook_handle) |
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| 69 | |
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| 70 | end subroutine calc_ice_optics_baran2016 |
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| 71 | |
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| 72 | end module radiation_ice_optics_baran2016 |
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