The NCAR Community Climate Model (CCM3)

Aug 28 1998: CRM 2.0 is available

Dear Colleague,

We are pleased to announce the release of the latest version of the CCM Column Radiation Model (CRM). CRM version 2.0 is available via the CRM homepage at URL http://www.cgd.ucar.edu/cms/crm.

The CRM is a standalone version of the column radiation code employed by the NCAR Community Climate Model (CCM3). Thus the CRM is a physical process model which isolates the energetics of radiative transfer from the rest of the CCM3. The CRM is built from the radiation routines from CCM3, along with a simple text interface for the user to input information needed by the radiation calculation.

The CRM uses a two-tier naming scheme which includes both the CRM version and the version of the CCM code with which it is bundled. The current distribution, crm-2.0-ccm-3.6, is CRM version 2.0 which is built on top of CCM version 3.6. The new CRM allows the user to take advantage of the more comprehensive trace gas, paleoclimate, and aerosol features of the latest CCM. In addition, the text and netCDF output files contain many more flux, albedo, and optical depth diagnostics. more detailed list of the changes and improvements to the CRM follows. Visit the CRM homepage at http://www.cgd.ucar.edu/cms/crm for more complete information.

Sincerely,
Charlie Zender

User-visible changes from CRM 1.16 to CRM 2.0

1. Input files for CRM 2.0 are backward-compatible with previous versions of CRM. Note, however that the meaning of the four albedo fields has changed slightly.
2. Source directory structure mimics CCM structure
3. Eight new input parameters:
   • N2O volume mixing ratio
   • CH4 volume mixing ratio
   • CFC11 volume mixing ratio
   • CFC12 volume mixing ratio
   • Aerosol visible extinction optical depth
   • Solar constant
   • Year AD
   • Longitude
4. CRM now requires netCDF, and must be compiled for IEEE double precision execution (internal representation as real*8).
5. Easy to configure band for extra diagnostics. Extra diagnostics will be output for the so-called "visible band". By default, this is set to SW band 8 (0.3500--0.6400 um). Simply edit the `bnd_idx_vsb' parameter in crmsrb.h to change bands.
6. Easy to configure boundary between visible and NIR spectral regions. For diagnostic purposes only, the partitioning between visible and NIR regions may be set by altering the parameter `wvl_vsb_NIR_bnd' in crmsrb.h. By default, the boundary is set to 0.7 um.
7. New output diagnostics in both text and netCDF files include: Column paths of H2O and O3 (also in Dobson Units) Column extinction optical depths Visible spectral fluxes Solar TOA radiation budget (including albedo ratios) Solar surface radiation budget (including direct/diffuse ratios)

Acknowledgements:

Erik Kluzek of NCAR/CGD/CMS has been very helpful in preparing this release of the CRM.

Brian Eaton of NCAR/CGD/CMS contributed the crm/bld/makdep script