! path: $Source: /storm/rc1/cvsroot/rc/rrtmg_sw/README,v $ ! author: $Author: mike $ ! revision: $Revision: 1.7 $ ! created: $Date: 2007/08/29 15:11:58 $ !------------------------------------------------------------------------ RRTMG_SW: Shortwave Radiative Transfer Model for GCMs Atmospheric and Environmental Research, Inc., 131 Hartwell Avenue, Lexington, MA 02421 Original version: Eli. J. Mlawer, J. S. Delamere, et al. (AER) Revision for GCMs: Michael J. Iacono (AER) Contact: Michael J. Iacono (E-mail: miacono@aer.com) Web Site: www.rtweb.aer.com Reference (RRTM_SW/RRTMG_SW): Clough, S.A., M.W. Shephard, E.J. Mlawer, J.S. Delamere, M.J. Iacono, K. Cady-Pereira, S. Boukabara, and P.D. Brown, Atmospheric radiative transfer modeling: a summary of the AER codes, J. Quant. Spectrosc. Radiat. Transfer, 91, 233-244, 2005. Reference (McICA): Pincus, R., H. W. Barker, and J.-J. Morcrette, A fast, flexible, approximation technique for computing radiative transfer in inhomogeneous cloud fields, J. Geophys. Res., 108(D13), 4376, doi:10.1029/2002JD003322, 2003. ****************************************************************************** This package contains the source code and sample makefiles necessary to run the latest version of RRTMG_SW, a correlated k-distribution shortwave radiative transfer model developed at AER, Inc. for application to GCMs. This version of RRTMG_SW utilizes a two-stream radiative transfer method as implemented at ECMWF. This code has also been modified to utilize FORTRAN90 coding features. Two modes of operation are possible. RRTMG_SW can be run in stand-alone mode using the input files and source modules described below, or it can be attached to an atmospheric general circulation model as a callable subroutine. The version of RRTMG_SW provided here utilizes a reduced complement of 112 g-points, which is half of the 224 g-points used in the standard RRTM_SW, and a two-stream method for radiative transfer. Additional minor changes have been made to enhance computational performance. Total fluxes are accurate to within 1-2 W/m2 relative to the standard RRTM_SW (using DISORT) in clear sky and in the presence of aerosols and within 6 W/m2 in overcast sky. RRTM_SW with DISORT is itself accurate to within 2 W/m2 of the data-validated multiple scattering model, CHARTS. This model can also utilize McICA, the Monte-Carlo Independent Column Approximation, to represent sub-grid scale cloud variability such as cloud fraction and cloud overlap. If the McICA option is selected to model a cloudy profile in column mode, then the model will run stochastically, and the output fluxes and heating rates will be an average over 200 samples. Without McICA, RRTMG_SW is limited to clear sky or overcast cloud conditions. *********************** RRTMG_SW column version *********************** DOCUMENTATION: The following text files (some in /column_model/doc directory) provide information on using and running RRTMG_SW: README : Basic code package information (this file) release_notes.txt : Code archive update information rrtmg_sw_instructions.txt : Input instructions for files INPUT_RRTM, IN_CLD_RRTM and IN_AER_RRTM SOURCE CODE: The following source files (in /column_model/src directory) must be used to run RRTMG_SW in stand-alone mode as a column model: rrtmg_sw.1col.f90 : Main module rrtmg_sw_cldprop.f90 : Calculation of cloud optical properties rrtmg_sw_cldprmc.f90 : Calculation of cloud optical properties (McICA) rrtmg_sw_init.f90 : RRTMG_SW initialization routine; reduces g-intervals from 224 to 112 rrtmg_sw_k_g.f90 : Absorption coefficient data file rrtmg_sw_reftra.f90 : Calculation of two-stream reflectivities and transmissivities rrtmg_sw_setcoef.f90 : Set up routine rrtmg_sw_spcvrt.f90 : Top subroutine for two-stream model rrtmg_sw_spcvmc.f90 : Top subroutine for two-stream model (McICA) rrtmg_sw_taumol.f90 : Calculation of optical depths and Planck fractions for each spectral band rrtmg_sw_vrtqdr.f90 : Two-stream vertical quadrature mcica_random_numbers.f90 : Random number generator for McICA mcica_subcol_gen_sw.1col.f90 : Sub-column generator for McICA rrtatm.f : Process user-defined input data files extra.f : Process input data files util_**.f : Utilities (available for multiple platforms) The following module files (in /column_model/modules directory) must be used to run RRTMG_SW in stand-alone mode as a column model (these must be compiled before the source code files): parkind.f90 : real and integer kind type parameters parrrsw.f90 : main configuration parameters rrsw_aer.f90 : aerosol property coefficients rrsw_cld.f90 : cloud property coefficients rrsw_con.f90 : constants rrsw_kg**.f90 : absorption coefficient arrays for 16 spectral bands rrsw_ref.f90 : reference atmosphere data arrays rrsw_tbl.f90 : exponential lookup table arrays rrsw_vsn.f90 : version number information rrsw_wvn.f90 : spectral band and g-interval array information MAKEFILES: The following files (in directory /column_model/build/makefiles) can be used to compile RRTMG_SW in stand-alone mode as a column model on various platforms. Link one of these into the /column_model/build directory to compile. make_rrtmg_sw_sgi : Sample makefile for SGI make_rrtmg_sw_sun : Sample makefile for SUN make_rrtmg_sw_linux_pgi : Sample makefile for LINUX (PGI compiler) make_rrtmg_sw_aix_xlf90 : Sample makefile for AIX (XLF90 compiler) make_rrtmg_sw_OS_X_g95 : Sample makefile for OS_X (G95 compiler) SAMPLE INPUT/OUTPUT: Several sample input (and output) files are included in the /runs_std_atm directory. Note that user-defined profiles may be used for as many as 200 layers. INPUT_RRTM : Required input file for (clear sky) atmospheric specification IN_CLD_RRTM : Required input file for cloud specification if clouds are present IN_AER_RRTM : Required input file for aerosol specification if aerosols are present OUTPUT_RRTM : Main output file for atmospheric fluxes and heating rates input_rrtm.MLS : Sample 51 layer mid-latitude summer standard atmosphere input_rrtm.MLS-cld-imca0 : Sample 51 layer mid-latitude summer standard atmosphere with cloud flag turn on (without McICA) input_rrtm.MLS-cld-imca1 : Sample 51 layer mid-latitude summer standard atmosphere with cloud flag turn on (with McICA) input_rrtm.SAW : Sample 51 layer sub-arctic winter standard atmosphere input_rrtm.TROP : Sample 51 layer tropical standard atmosphere in_cld_rrtm-cld5 : Sample cloud input file in_aer_rrtm-aer12 : Sample aerosol input file ********************* RRTMG_SW: GCM version ********************* DOCUMENTATION: README : Basic code package information (this file) SOURCE CODE: The following source files (in /gcm_model/src directory) must be used to run RRTMG_SW as a callable subroutine: rrtmg_sw.f90 : RRTMG_SW main module (with McICA) rrtmg_sw.nomcica.f90 : Optional RRTMG_SW main module (without McICA only) rrtmg_sw_cldprop.f90 : Calculation of cloud optical properties rrtmg_sw_cldprmc.f90 : Calculation of cloud optical properties (McICA) rrtmg_sw_init.f90 : RRTMG_SW initialization routine; reduces g-intervals from 224 to 112; (This has to run only once and should be installed in the GCM initialization section) rrtmg_sw_k_g.f90 : Absorption coefficient data file rrtmg_sw_reftra.f90 : Calculation of two-stream reflectivities and transmissivities rrtmg_sw_setcoef.f90 : Set up routine rrtmg_sw_spcvrt.f90 : Top subroutine for two-stream model rrtmg_sw_spcvmc.f90 : Top subroutine for two-stream model (McICA) rrtmg_sw_taumol.f90 : Calculation of optical depths and Planck fractions for each spectral band rrtmg_sw_vrtqdr.f90 : Two-stream vertical quadrature mcica_random_numbers.f90 : Random number generator for McICA mcica_subcol_gen_sw.f90 : Sub-column generator for McICA The following module files (in /gcm_model/modules directory) must be used to run RRTMG_SW as a callable subroutine (these must be compiled before the source code files): parkind.f90 : real and integer kind type parameters parrrsw.f90 : main configuration parameters rrsw_aer.f90 : aerosol property coefficients rrsw_cld.f90 : cloud property coefficients rrsw_con.f90 : constants rrsw_kg**.f90 : absorption coefficient arrays for 16 spectral bands rrsw_ref.f90 : reference atmosphere data arrays rrsw_tbl.f90 : exponential lookup table arrays rrsw_vsn.f90 : version number information rrsw_wvn.f90 : spectral band and g-interval array information Notes regarding GCM version: 1) The module rrtmg_sw_init.f90 is the initialization routine that has to be called only once. The call to this subroutine should be moved to the initialization section of the host model if RRTMG_SW is called by a GCM or SCM. 2) The number of model layers and the number of columns to be looped over should be passed into RRTMG_SW through the subroutine call along with the other model profile arrays. 3) To utilize McICA, the sub-column generator (mcica_subcol_gen_sw.f90) must be implemented in the GCM so that it is called just before RRTMG. If McICA is utilized, this will run only a single statistical sample per model grid box. There are two options for the random number generator used with McICA, which is selected with the variable irnd in mcica_subcol_gen_sw.f90. When using McICA, the main RRTMG_SW module is rrtmg_sw.f90. If McICA is not used, then the main module is rrtmg_sw.nomcica.f90, though cloud specification is limited to overcast clouds.