Cloud Optical Property in SW

SUBROUTINE cldprop in module_radsw_main computes the cloud optical properties for each cloudy layer and g-point interval.
Usage:
call cldprop
!— inputs:
& ( cfrac,cliqp,reliq,cicep,reice,cdat1,cdat2,cdat3,cdat4, &
& cf1, nlay, ipseed, &
! — output:
& taucw, ssacw, asycw, cldfrc, cldfmc &
& )

Parameters

[in]	cfrac	- real, (nlay), layer cloud fraction ..... for iswcliq > 0 (prognostic cloud scheme) - - -
[in]	cliqp	- real, (nlay), layer in-cloud liq water path ( \(g/m^2\))
[in]	reliq	- real, (nlay), mean eff radius for liq cloud (micron)
[in]	cicep	- real, (nlay), layer in-cloud ice water path ( \(g/m^2\))
[in]	reice	- real, (nlay), mean eff radius for ice cloud (micron)
[in]	cdat1	- real, (nlay), layer rain drop water path ( \(g/m^2\))
[in]	cdat2	- real, (nlay), effective radius for rain drop (micron)
[in]	cdat3	- real, (nlay), layer snow flake water path( \(g/m^2\))
[in]	cdat4	- real, (nlay), mean eff radius for snow flake(micron) ..... for iswcliq = 0 (diagnostic cloud scheme) - - -
[in]	cliqp	- real, (nlay), not used
[in]	cicep	- real, (nlay), not used
[in]	reliq	- real, (nlay), not used
[in]	reice	- real, (nlay), not used
[in]	cdat1	- real, (nlay), layer cloud optical depth
[in]	cdat2	- real, (nlay), layer cloud single scattering albedo
[in]	cdat3	- real, (nlay), layer cloud asymmetry factor
[in]	cdat4	- real, (nlay), optional use
[in]	cf1	- real, 1, effective total cloud cover at surface
[in]	nlay	- integer, 1, vertical layer number
[in]	ipseed-	permutation seed for generating random numbers (isubcsw>0)
[out]	taucw	- real,nlay*nbdsw, cloud optical depth, w/o delta scaled
[out]	ssacw	- real,nlay*nbdsw, weighted cloud single scattering albedo (ssa = ssacw / taucw)
[out]	asycw	- real,nlay*nbdsw, weighted cloud asymmetry factor (asy = asycw / ssacw)
[out]	cldfrc	- real,nlay, cloud fraction of grid mean value
[out]	cldfmc	- real,nlay*ngptsw, cloud fraction for each sub-column

General Algorithm

1. Compute cloud radiative properties for a cloudy column
   • Compute cloud radiative properties for rain and snow:
     For Rain: tauran/ssaran/asyran
     For Snow: tausnw/ssasnw/asysnw
   • Calculation of sbsorption coefficients due to water clouds (iswcliq=1, use hu and stamnes(1993) method)
     For water clouds: tauliq/ssaliq/asyliq
   • Calcultaion of absorption coefficients due to ice clouds (iswcice = 3, use fu's method (1996))
     For ice clouds tauice/ssaice/asyice
   • For prognostic cloud scheme: sum up the cloud optical property:
     \( taucw=tauliq+tauice+tauran+tausnw \)
     \( ssacw=ssaliq+ssaice+ssaran+ssasnw \)
     \( asycw=asyliq+asyice+asyran+asysnw \)
2. Distribute cloud properties to each g-point (isubcsw = 0, for non-mcica, normalize cloud)