GFS RRTMG-SW Main Module

This module includes NCEP's modifications of the RRTMG-SW radiation code from AER. More...

Modules
module	module_radsw_parameters
	This module is for specifying the band structures and program parameters used by the RRTMG-SW scheme.
module	module_radsw_ref
	This module contains the reference pressures (in logarithm form) at 59 vertical levels (TOA is omitted), and the mid-latitude summer (MLS) standard temperature profile for the 59 pressure layers that are used to establish pre calculated transmission tables.
module	module_radsw_cldprtb
	This module contains cloud radiative property coefficients.
module	module_radsw_sflux
	This module contains various indexes and coefficients for SW spectral bands, as well as the spectral distribution of solar flux. The values of spectral solar flux are derived based on a prescribed solar constant ( \(1368.22 W/m^2\)). Scaling will be applied for the actual inputted solar constant value.
module	module_radsw_kgb16
	This module sets up absorption coefficients for band 16: 2600-3250 cm-1 (low - h2o, ch4; high - ch4)
module	module_radsw_kgb17
	This module sets up absorption coeffients for band 17: 3250-4000 cm-1 (low - h2o,co2; high - h2o,co2)
module	module_radsw_kgb18
	This module sets up absorption coeffients for band 18: 4000-4650 cm-1 (low - h2o,ch4; high - ch4)
module	module_radsw_kgb19
	This module sets up absorption coeffients for band 19: 4650-5150 cm-1 (low - h2o,co2; high - co2)
module	module_radsw_kgb20
	This module sets up absorption coeffients for band 20: 5150-6150 cm-1 (low - h2o; high - h2o)
module	module_radsw_kgb21
	This module sets up absorption coeffients for band 21: 6150-7700 cm-1 (low - h2o,co2; high - h2o,co2)
module	module_radsw_kgb22
	This module sets up absorption coeffients for band 22: 7700-8050 cm-1 (low - h2o, o2; high - o2)
module	module_radsw_kgb23
	This module sets up absorption coeffients for band 23: 8050-12850 cm-1 (low - h2o; high - nothing)
module	module_radsw_kgb24
	This module sets up absorption coeffients for band 24: 12850-16000 cm-1 (low - h2o, o2; high - o2)
module	module_radsw_kgb25
	This module sets up absorption coeffients for band 25: 16000-22650 cm-1 (low - h2o; high - nothing)
module	module_radsw_kgb26
	This module sets up absorption coeffients for band 26: 22650-29000 cm-1 (low - nothing; high - nothing)
module	module_radsw_kgb27
	This module sets up absorption coeffients for band 27: 29000-38000 cm-1 (low - o3; high - o3)
module	module_radsw_kgb28
	This module sets up absorption coeffients for band 28: 38000-50000 cm-1 (low - o3,o2; high - o3,o2)
module	module_radsw_kgb29
	This module sets up absorption coeffients for band 29: 820-2600 cm-1 (low - h2o; high - co2)

Functions/Subroutines
subroutine, public	rrtmg_sw::rrtmg_sw_run (plyr, plvl, tlyr, tlvl, qlyr, olyr, gasvmr_co2, gasvmr_n2o, gasvmr_ch4, gasvmr_o2, gasvmr_co, gasvmr_cfc11, gasvmr_cfc12, gasvmr_cfc22, gasvmr_ccl4, icseed, aeraod, aerssa, aerasy, sfcalb_nir_dir, sfcalb_nir_dif, sfcalb_uvis_dir, sfcalb_uvis_dif, dzlyr, delpin, de_lgth, alpha, cosz, solcon, NDAY, idxday, npts, nlay, nlp1, lprnt, cld_cf, lsswr, hswc, topflx, sfcflx, cldtau, HSW0, HSWB, FLXPRF, FDNCMP, cld_lwp, cld_ref_liq, cld_iwp, cld_ref_ice, cld_rwp, cld_ref_rain, cld_swp, cld_ref_snow, cld_od, cld_ssa, cld_asy, errmsg, errflg)
subroutine, public	rrtmg_sw::rswinit (me)
	This subroutine initializes non-varying module variables, conversion factors, and look-up tables. More...
subroutine	rrtmg_sw::cldprop (cfrac, cliqp, reliq, cicep, reice, cdat1, cdat2, cdat3, cdat4, cf1, nlay, ipseed, dz, delgth, alpha, taucw, ssacw, asycw, cldfrc, cldfmc)
	This subroutine computes the cloud optical properties for each cloudy layer and g-point interval. More...
subroutine	rrtmg_sw::mcica_subcol (cldf, nlay, ipseed, dz, de_lgth, alpha, lcloudy)
	This subroutine computes the sub-colum cloud profile flag array. More...
subroutine	rrtmg_sw::setcoef (pavel, tavel, h2ovmr, nlay, nlp1, laytrop, jp, jt, jt1, fac00, fac01, fac10, fac11, selffac, selffrac, indself, forfac, forfrac, indfor)
	This subroutine computes various coefficients needed in radiative transfer calculation. More...
subroutine	rrtmg_sw::spcvrtc (ssolar, cosz, sntz, albbm, albdf, sfluxzen, cldfrc, cf1, cf0, taug, taur, tauae, ssaae, asyae, taucw, ssacw, asycw, nlay, nlp1, fxupc, fxdnc, fxup0, fxdn0, ftoauc, ftoau0, ftoadc, fsfcuc, fsfcu0, fsfcdc, fsfcd0, sfbmc, sfdfc, sfbm0, sfdf0, suvbfc, suvbf0)
	This subroutine computes the shortwave radiative fluxes using two-stream method. More...
subroutine	rrtmg_sw::spcvrtm (ssolar, cosz, sntz, albbm, albdf, sfluxzen, cldfmc, cf1, cf0, taug, taur, tauae, ssaae, asyae, taucw, ssacw, asycw, nlay, nlp1, fxupc, fxdnc, fxup0, fxdn0, ftoauc, ftoau0, ftoadc, fsfcuc, fsfcu0, fsfcdc, fsfcd0, sfbmc, sfdfc, sfbm0, sfdf0, suvbfc, suvbf0)
	This subroutine computes the shortwave radiative fluxes using two-stream method of h. barder and mcica,the monte-carlo independent column approximation, for the representation of sub-grid cloud variability (i.e. cloud overlap). More...
subroutine	rrtmg_sw::vrtqdr (zrefb, zrefd, ztrab, ztrad, zldbt, ztdbt, NLAY, NLP1, zfu, zfd)
	This subroutine is called by spcvrtc() and spcvrtm(), and computes the upward and downward radiation fluxes. More...
subroutine	rrtmg_sw::taumol (colamt, colmol, fac00, fac01, fac10, fac11, jp, jt, jt1, laytrop, forfac, forfrac, indfor, selffac, selffrac, indself, nlay, sfluxzen, taug, taur)
	This subroutine calculates optical depths for gaseous absorption and rayleigh scattering subroutine called taumol## (## = 16-29) More...
subroutine	taumol16
	The subroutine computes the optical depth in band 16: 2600-3250 cm-1 (low - h2o,ch4; high - ch4) More...
subroutine	taumol17
	The subroutine computes the optical depth in band 17: 3250-4000 cm-1 (low - h2o,co2; high - h2o,co2) More...
subroutine	taumol18
	The subroutine computes the optical depth in band 18: 4000-4650 cm-1 (low - h2o,ch4; high - ch4) More...
subroutine	taumol19
	The subroutine computes the optical depth in band 19: 4650-5150 cm-1 (low - h2o,co2; high - co2) More...
subroutine	taumol20
	The subroutine computes the optical depth in band 20: 5150-6150 cm-1 (low - h2o; high - h2o) More...
subroutine	taumol21
	The subroutine computes the optical depth in band 21: 6150-7700 cm-1 (low - h2o,co2; high - h2o,co2) More...
subroutine	taumol22
	The subroutine computes the optical depth in band 22: 7700-8050 cm-1 (low - h2o,o2; high - o2) More...
subroutine	taumol23
	The subroutine computes the optical depth in band 23: 8050-12850 cm-1 (low - h2o; high - nothing) More...
subroutine	taumol24
	The subroutine computes the optical depth in band 24: 12850-16000 cm-1 (low - h2o,o2; high - o2) More...
subroutine	taumol25
	The subroutine computes the optical depth in band 25: 16000-22650 cm-1 (low - h2o; high - nothing) More...
subroutine	taumol26
	The subroutine computes the optical depth in band 26: 22650-29000 cm-1 (low - nothing; high - nothing) More...
subroutine	taumol27
	The subroutine computes the optical depth in band 27: 29000-38000 cm-1 (low - o3; high - o3) More...
subroutine	taumol28
	The subroutine computes the optical depth in band 28: 38000-50000 cm-1 (low - o3,o2; high - o3,o2) More...
subroutine	taumol29
	The subroutine computes the optical depth in band 29: 820-2600 cm-1 (low - h2o; high - co2) More...

Detailed Description

The SW radiation model in the current NOAA Environmental Modeling System (NEMS) was adapted from the RRTM radiation model developed by AER Inc. ([41]; [136]). It contains 14 spectral bands spanning a spectral wavenumber range of \(50000-820 cm^{-1}\) (corresponding to a wavelength range \(0.2-12.2\mu m\)), each spectral band focuses on a specific set of atmospheric absorbing species as shown in Table 1. To achieve great computation efficiency while at the same time to maintain a high degree of accuracy, the RRTM radiation model employs a corrected-k distribution method (i.e. mapping the highly spectral changing absorption coefficient, k, into a monotonic and smooth varying cumulative probability function, g). In the RRTM-SW, there are 16 unevenly distributed g points for each of the 14 bands for a total of 224 g points. The GCM version of the code (RRTMG-SW) uses a reduced number (various between 2 to 16) of g points for each of the bands that totals to 112 instead of the full set of 224. To get high quality for the scheme, many advanced techniques are used in RRTM such as carefully selecting the band structure to handle various major (key-species) and minor absorbers; deriving a binary parameter for a paired key molecular species in the same domain; and using two pressure regions (dividing level is at about 96mb) for optimal treatment of various species, etc.

Table 1. RRTMG-SW spectral bands and the corresponding absorbing species

Band #	Wavenumber Range	Lower Atm (Key)	Lower Atm (Minor)	Mid/Up Atm (Key)	Mid/Up Atm (Minor)
16	2600-3250	H2O,CH4		CH4
17	3250-4000	H2O,CO2		H2O,CO2
18	4000-4650	H2O,CH4		CH4
19	4650-5150	H2O,CO2		CO2
20	5150-6150	H2O	CH4	H2O	CH4
21	6150-7700	H2O,CO2		H2O,CO2
22	7700-8050	H2O,O2		O2
23	8050-12850	H2O		—
24	12850-16000	H2O,O2	O3	O2	O3
25	16000-22650	H2O	O3	—	O3
26	22650-29000	—		—
27	29000-38000	O3		O3
28	38000-50000	O3,O2		O3,O2
29	820-2600	H2O	CO2	CO2	H2O

The RRTMG-SW package includes three files:

• radsw_param.f, which contains:
  • module_radsw_parameters: specifies major parameters of the spectral bands and defines the construct structures of derived-type variables for holding the output results.
• radsw_datatb.f, which contains:
  • module_radsw_ref: reference temperature and pressure
  • module_radsw_cldprtb: cloud property coefficients table
  • module_radsw_sflux: indexes and coefficients for spectral distribution of solar flux
  • module_radsw_kgbnn: absorption coefficents for 14 bands, where nn = 16-29
• radsw_main.f, which contains:
  • rrtmg_sw_run(): the main SW radiation routine
  • rswinit(): the initialization routine

Author

Eli J. Mlawer, emlaw.nosp@m.er@a.nosp@m.er.co.nosp@m.m

Jennifer S. Delamere, jdela.nosp@m.mer@.nosp@m.aer.c.nosp@m.om

Michael J. Iacono, miaco.nosp@m.no@a.nosp@m.er.co.nosp@m.m

Shepard A. Clough

Version

NCEP SW v5.1 Nov 2012 -RRTMG-SW v3.8

The authors wish to acknowledge the contributions of the following people: Steven J. Taubman, Karen Cady-Pereira, Patrick D. Brown, Ronald E. Farren, Luke Chen, Robert Bergstrom.

Copyright

2002-2007, Atmospheric & Environmental Research, Inc. (AER). This software may be used, copied, or redistributed as long as it is not sold and this copyright notice is reproduced on each copy made. This model is provided as is without any express or implied warranties. (http://www.rtweb.aer.com/)

Argument Table

local_name	standard_name	long_name	units	type	dimensions	kind	intent
plyr	air_pressure_at_layer_for_radiation_in_hpa	air pressure layer	hPa	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
plvl	air_pressure_at_interface_for_radiation_in_hpa	air pressure level	hPa	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_level_dimension_for_radiation)	kind_phys	in
tlyr	air_temperature_at_layer_for_radiation	air temperature layer	K	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
tlvl	air_temperature_at_interface_for_radiation	air temperature level	K	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_level_dimension_for_radiation)	kind_phys	in
qlyr	water_vapor_specific_humidity_at_layer_for_radiation	specific humidity layer	kg kg-1	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
olyr	ozone_concentration_at_layer_for_radiation	ozone concentration layer	kg kg-1	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_co2	volume_mixing_ratio_of_co2	volume mixing ratio co2	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_n2o	volume_mixing_ratio_of_n2o	volume mixing ratio no2	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_ch4	volume_mixing_ratio_of_ch4	volume mixing ratio ch4	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_o2	volume_mixing_ratio_of_o2	volume mixing ratio o2	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_co	volume_mixing_ratio_of_co	volume mixing ratio co	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_cfc11	volume_mixing_ratio_of_cfc11	volume mixing ratio cfc11	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_cfc12	volume_mixing_ratio_of_cfc12	volume mixing ratio cfc12	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_cfc22	volume_mixing_ratio_of_cfc22	volume mixing ratio cfc22	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
gasvmr_ccl4	volume_mixing_ratio_of_ccl4	volume mixing ratio ccl4	m3 m-3	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
icseed	random_number_seed_for_mcica_shortwave	seed for random number generation for shortwave radiation	none	integer	(ccpp_constant_one:horizontal_loop_extent)		in
aeraod	aerosol_optical_depth_for_shortwave_bands_01_16	aerosol optical depth for shortwave bands 01-16	none	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation, ccpp_constant_one:number_of_aerosol_bands_for_shortwave_radiation)	kind_phys	in
aerssa	aerosol_single_scattering_albedo_for_shortwave_bands_01_16	aerosol single scattering albedo for shortwave bands 01-16	frac	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation, ccpp_constant_one:number_of_aerosol_bands_for_shortwave_radiation)	kind_phys	in
aerasy	aerosol_asymmetry_parameter_for_shortwave_bands_01_16	aerosol asymmetry paramter for shortwave bands 01-16	none	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation, ccpp_constant_one:number_of_aerosol_bands_for_shortwave_radiation)	kind_phys	in
sfcalb_nir_dir	surface_albedo_due_to_near_ir_direct	surface albedo due to near IR direct beam	frac	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
sfcalb_nir_dif	surface_albedo_due_to_near_ir_diffused	surface albedo due to near IR diffused beam	frac	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
sfcalb_uvis_dir	surface_albedo_due_to_uv_and_vis_direct	surface albedo due to UV+VIS direct beam	frac	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
sfcalb_uvis_dif	surface_albedo_due_to_uv_and_vis_diffused	surface albedo due to UV+VIS diffused beam	frac	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
dzlyr	layer_thickness_for_radiation	layer thickness	km	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
delpin	layer_pressure_thickness_for_radiation	layer pressure thickness	hPa	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
de_lgth	cloud_decorrelation_length	cloud decorrelation length	km	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
alpha	cloud_overlap_decorrelation_parameter	cloud overlap decorrelation parameter	frac	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cosz	cosine_of_solar_zenith_angle_for_daytime_points_on_radiation_timestep	cosine of the solar zenit angle	none	real	(ccpp_constant_one:horizontal_loop_extent)	kind_phys	in
solcon	solar_constant	solar constant	W m-2	real	()	kind_phys	in
nday	daytime_points_dimension	daytime points dimension	count	integer	()		in
idxday	daytime_points	daytime points	index	integer	(ccpp_constant_one:horizontal_loop_extent)		in
npts	horizontal_loop_extent	horizontal dimension	count	integer	()		in
nlay	adjusted_vertical_layer_dimension_for_radiation	number of vertical layers for radiation	count	integer	()		in
nlp1	adjusted_vertical_level_dimension_for_radiation	number of vertical levels for radiation	count	integer	()		in
lprnt	flag_print	flag to print	flag	logical	()		in
cld_cf	total_cloud_fraction	total cloud fraction	frac	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
lsswr	flag_for_calling_shortwave_radiation	flag to calculate SW irradiances	flag	logical	()		in
hswc	tendency_of_air_temperature_due_to_shortwave_heating_on_radiation_time_step_and_radiation_levels	shortwave total sky heating rate	K s-1	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	inout
topflx	sw_fluxes_top_atmosphere	shortwave total sky fluxes at the top of the atm	W m-2	topfsw_type	(ccpp_constant_one:horizontal_loop_extent)	topfsw_type	inout
sfcflx	surface_sw_fluxes_assuming_total_and_clear_sky_on_radiation_timestep	shortwave total sky fluxes at the Earth surface	W m-2	sfcfsw_type	(ccpp_constant_one:horizontal_loop_extent)	sfcfsw_type	inout
cldtau	cloud_optical_depth_layers_at_0p55mu_band	approx .55mu band layer cloud optical depth	none	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	inout
hsw0	tendency_of_air_temperature_due_to_shortwave_heating_assuming_clear_sky_on_radiation_time_step_and_radiation_levels	shortwave clear sky heating rate	K s-1	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	inout
fdncmp	components_of_surface_downward_shortwave_fluxes	derived type for special components of surface downward shortwave fluxes	W m-2	cmpfsw_type	(ccpp_constant_one:horizontal_loop_extent)	cmpfsw_type	inout
cld_lwp	cloud_liquid_water_path	cloud liquid water path	g m-2	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_ref_liq	mean_effective_radius_for_liquid_cloud	mean effective radius for liquid cloud	um	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_iwp	cloud_ice_water_path	cloud ice water path	g m-2	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_ref_ice	mean_effective_radius_for_ice_cloud	mean effective radius for ice cloud	um	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_rwp	cloud_rain_water_path	cloud rain water path	g m-2	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_ref_rain	mean_effective_radius_for_rain_drop	mean effective radius for rain drop	um	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_swp	cloud_snow_water_path	cloud snow water path	g m-2	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
cld_ref_snow	mean_effective_radius_for_snow_flake	mean effective radius for snow flake	um	real	(ccpp_constant_one:horizontal_loop_extent, ccpp_constant_one:adjusted_vertical_layer_dimension_for_radiation)	kind_phys	in
errmsg	ccpp_error_message	error message for error handling in CCPP	none	character	()	len=*	out
errflg	ccpp_error_code	error code for error handling in CCPP	1	integer	()		out

RRTMG Shortwave Radiation Scheme General Algorithm