Linking GEOS-Chem to CMAQ

This page contains information about how to link the GEOS-Chem chemistry mechanism, output, and met fields with the CMAQ regional air quality model.

Overview

Tao Zeng wrote:

The code to convert GEOS-Chem simulations as the boundary and initial conditions for CMAQ CB05 is ready. I have tested it successfully on GEOS-Chem v08-01-04 using pgf90 compiler. Some highlights are:

(1) 2 output options:

• (a) in CMAQ domain after regridding. The outputs are CMAQ ready BC/IC files with NetCDF format. The MCIP met file (GRIDCRO3D and GRIDCRO2D) and default CMAQ IC/BC are required. IOAPI and NetCDF libs are also needed.
• (b) in G-C subdomain without regridding. It is in binary format.

(2) Conversion of GOS-Chem species to CB05 tracers

• Tracer mapping table are designed to convert GEOS-Chem species to CMAQ tracers. Rob Pinder from EPA helped me to review it.
• CSPEC array is used to get direct NO and NO2 concentrations. Some other species in CSPEC but not in STT are also included. Several inactive species (ACTA, EOH, HCOOH, and MOH) are turned on into active species to get better mapping of CB05 tracers. This resulting differences are <1% in average over the domain after 1 month integration. And the max difference is ~2% for most tracers. But for NH3 and NIT, the max differences are up to 50% when they are at very low level.

(3) To avoid excess downward transport from stratosphere in CMAQ, tracer concentrations at the tropopause in GEOS-Chem are used to for the tropopause and the layers above.

Any suggestions are welcome. The whole package includes a new fortran module file and some lines adding into 3 files. If anybody is interested, please let me know.

--Bob Y. 10:19, 10 March 2010 (EST)