subroutine rrtmg_sw::spcvrtm ( real (kind=kind_phys), intent(in)  ssolar, real (kind=kind_phys), intent(in)  cosz, real (kind=kind_phys), intent(in)  sntz, real (kind=kind_phys), dimension(2), intent(in)  albbm, real (kind=kind_phys), dimension(2), intent(in)  albdf, real (kind=kind_phys), dimension(ngptsw), intent(in)  sfluxzen, real (kind=kind_phys), dimension(nlay,ngptsw), intent(in)  cldfmc, real (kind=kind_phys), intent(in)  cf1, real (kind=kind_phys), intent(in)  cf0, real (kind=kind_phys), dimension(nlay,ngptsw), intent(in)  taug, real (kind=kind_phys), dimension(nlay,ngptsw), intent(in)  taur, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  tauae, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  ssaae, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  asyae, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  taucw, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  ssacw, real (kind=kind_phys), dimension(nlay,nbdsw), intent(in)  asycw, integer, intent(in)  nlay, integer, intent(in)  nlp1, real (kind=kind_phys), dimension(nlp1,nbdsw), intent(out)  fxupc, real (kind=kind_phys), dimension(nlp1,nbdsw), intent(out)  fxdnc, real (kind=kind_phys), dimension(nlp1,nbdsw), intent(out)  fxup0, real (kind=kind_phys), dimension(nlp1,nbdsw), intent(out)  fxdn0, real (kind=kind_phys), intent(out)  ftoauc, real (kind=kind_phys), intent(out)  ftoau0, real (kind=kind_phys), intent(out)  ftoadc, real (kind=kind_phys), intent(out)  fsfcuc, real (kind=kind_phys), intent(out)  fsfcu0, real (kind=kind_phys), intent(out)  fsfcdc, real (kind=kind_phys), intent(out)  fsfcd0, real (kind=kind_phys), dimension(2), intent(out)  sfbmc, real (kind=kind_phys), dimension(2), intent(out)  sfdfc, real (kind=kind_phys), dimension(2), intent(out)  sfbm0, real (kind=kind_phys), dimension(2), intent(out)  sfdf0, real (kind=kind_phys), intent(out)  suvbfc, real (kind=kind_phys), intent(out)  suvbf0  )

private

Parameters

ssolar	incoming solar flux at top
cosz	cosine solar zenith angle
sntz	secant solar zenith angle
albbm	surface albedo for direct beam radiation
albdf	surface albedo for diffused radiation
sfluxzen	spectral distribution of incoming solar flux
cldfmc	layer cloud fraction for g-point
cf1	>0: cloudy sky, otherwise: clear sky
cf0	=1-cf1
taug	spectral optical depth for gases
taur	optical depth for rayleigh scattering
tauae	aerosols optical depth
ssaae	aerosols single scattering albedo
asyae	aerosols asymmetry factor
taucw	weighted cloud optical depth
ssacw	weighted cloud single scat albedo
asycw	weighted cloud asymmetry factor
nlay,nlp1	number of layers/levels
fxupc	tot sky upward flux
fxdnc	tot sky downward flux
fxup0	clr sky upward flux
fxdn0	clr sky downward flux
ftoauc	tot sky toa upwd flux
ftoau0	clr sky toa upwd flux
ftoadc	toa downward (incoming) solar flux
fsfcuc	tot sky sfc upwd flux
fsfcu0	clr sky sfc upwd flux
fsfcdc	tot sky sfc dnwd flux
fsfcd0	clr sky sfc dnwd flux
sfbmc	tot sky sfc dnwd beam flux (nir/uv+vis)
sfdfc	tot sky sfc dnwd diff flux (nir/uv+vis)
sfbm0	clr sky sfc dnwd beam flux (nir/uv+vis)
sfdf0	clr sky sfc dnwd diff flux (nir/uv+vis)
suvbfc	tot sky sfc dnwd uv-b flux
suvbf0	clr sky sfc dnwd uv-b flux

spcvrtm General Algorithm

1. Initialize output fluxes.
2. Loop over all g-points in each band.
3. Set up toa direct beam and surface values (beam and diff).
4. Compute clear-sky optical parameters, layer reflectance and transmittance.
   • Saving clear-sky quantities for later total-sky usage.
   • Delta scaling for clear-sky condition.
   • Perform general two-stream expressions:
     control parameters in module "physparam"
     iswmode - control flag for 2-stream transfer schemes
     = 1 delta-eddington (joseph et al., 1976)
     = 2 pifm (zdunkowski et al., 1980)
     = 3 discrete ordinates (liou, 1973)
   • Compute homogeneous reflectance and transmittance.
   • Calculate direct beam transmittance. use exponential lookup table for transmittance, or expansion of exponential for low optical depth.
   • Calculate pre-delta-scaling clear and cloudy direct beam transmittance.
5. Call vrtqdr(), to compute the upward and downward radiation fluxes.
6. Compute upward and downward fluxes at levels.
7. Compute surface downward beam/diffuse flux components.
8. Compute total sky optical parameters, layer reflectance and transmittance.
   • Set up toa direct beam and surface values (beam and diff).
   • Perform delta scaling for total-sky condition.
   • Perform general two-stream expressions.
   • Compute homogeneous reflectance and transmittance for both convertive and non-convertive scattering.
   • Calculate pre-delta-scaling clear and cloudy direct beam transmittance.
9. Call vrtqdr(), to perform vertical quadrature
10. Process and save outputs.
    • surface downward beam/diffused flux components
    • uv-b surface downward flux
    • surface downward beam/diffused flux components
    • uv-b surface downward flux

References physparam::iswmode, and vrtqdr().

Referenced by rrtmg_sw_run().

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