Linking GEOS-Chem to CMAQ

NOTE: Page under construction!

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

Brief description

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)

Authors and collaborators

• Tao Zeng (Georgia EPD)

User groups

User Group	Personnel	Projects
Georgia EPD	Tao Zeng	...
Add yours here...	...	...

Source code

Tao Zeng has provided the GEOS-Chem to CMAQ source code linkage. It is available for download from:

ftp ftp.as.harvard.edu
get pub/geos-chem/downloads/geoschem4cmaq.20100316.tgz

To extract the archive, type:

tar xvzf geoschem4cmaq.20100316.tgz

You will find a README.txt file in the archive with more information.

--Bob Y. 15:27, 16 March 2010 (EDT)

References

1. CMAQ model web page
2. GEOS-Chem chemistry mechanism

Known issues

SOA1, SOA2, SOA3, and SOA4 in G-C are outputed but are not converted to CB05 tracers. In CMAQ v4.7, 19 SOA species are defined. The CMAQ release notes do not fully explain them. So I will update this package when possible.