RRTMG_LW What's New:


Validation results of latest version of RRTMG_LW relative to LBLRTM.


RRTMG_LW v4.71

Date: September 2008

  • Modified input of ice particle effective size to require input of value appropriate for the selected ice optics parameterization. Previous scaling that was applied internally to convert ice effective radius to generalized effective size for the Fu parameterization has been removed. Any necessary scaling needed to provide the proper ice particle size must be done before input to the radiation in the GCM version of the code. This is consistent with the input requirement for the column version of the model. Note that the internal ice optics parameterizations are effective over specific ranges of particle size. Results may be different from previous versions if the Fu parameterization is used in the GCM version of the code. Also, fixed the definition of the secant of the diffusivity angle, which varies as a function of the water column amount. This change only affects results in profiles with more than eight precipitable cm of water vapor.

RRTMG_LW v4.7

Date: August 2008

  • Added requirement that cloud liquid and ice water paths, or optionally the cloud optical depth, be input as in-cloud averages rather than grid-averaged values in the version of the code intended for use in a GCM. This change requires that these cloud properties be scaled by the cloud fraction on input to convert to in-cloud values if necessary. The column model version of the code continues to expect in-cloud values as before. Oxygen amount was changed from being defined internally to a required input. Several other cosmetic modifications do not affect results, but a change in the factor used to convert flux to heating rate from a fixed to a calculated quantity may produce negligible differences in heating rates.

RRTMG_LW v4.5

Date: April 2008

  • Added capability to treat longwave aerosol absorption and added use of input file IN_AER_RRTM to read in aerosol optical depths following the application of this file in RRTMG_SW. Aerosol scattering is not presently available in the longwave, so the required input is limited to the aerosol optical depth by layer at the mid-point of each of the 16 spectral bands.

RRTMG_LW v4.4

Date: September 2007

  • Modified use of ice particle size variables rei/reicmc to utilize separate variable names (dge/dgesmc) when units of generalized effective size are required for Fu ice parameterization (iceflag=3) option. Results may be minimally affected when ice particle radii exceed 90 microns and the iceflag=3 option is used. Also modified several local arrays in top-level subroutine module to accomodate an extra model layer at the top of the atmosphere if this feature is utilized when using the code in a GCM.

RRTMG_LW v4.3

Date: August 2007

  • Includes changes to the makefile for AIX systems and a few minor fixes in the interface for the subroutine version of the model. Results are identical to the previous version.

RRTMG_LW v4.1

Date: August 2007

  • Includes several format changes to retain consistency with RRTMG_SW. Results are identical to the previous version.

RRTMG_LW v4.0.2

Date: May 2007

  • Made several minor adjustments to kind type suffixes in several modules and made changes to the README file. Results are identical to the previous version.

RRTMG_LW v4.0.1

Date: April 2007

  • Includes minor bug fix to the dimension of arrays abscoice and abscoliq in rrtmg_lw_cldprmc.f90, which affected results on some compilers.

RRTMG_LW v4.0

Date: April 2007

  • Major source code reformatting to utilize modern FORTRAN90 features such as modules. Older common blocks have been removed from all but I/O related source files to retain I/O compatibility with RRTM.

  • Model can be run as a stand-alone column model using the same I/O format as RRTM and LBLRTM, or it can be used as a callable subroutine and implemented within a global or regional model.

  • McICA (Monte Carlo Independent Column Approximation) capabililty added for representation of sub-grid cloud variability such as cloud fraction and cloud overlap.

  • Includes two options for the random number generator needed for McICA.

  • Sample makefiles for several computer platforms are provided.

  • Sample input and output files and instructions for the input files are also included in the source package.



Atmospheric and Environmental Research Inc. (AER)