UCX chemistry mechanism
On this page, we provide information about the Universal tropospheric-stratospheric Chemistry eXtension (UCX) mechanism in GEOS-Chem. UCX combines both tropospheric and stratospheric reactions into a single chemistry mechanism. It was developed by Sebastian Eastham, Debra Weisenstein, and Steven Barrett at the Laboratory for Aviation and the Environment at the Massachusetts Institute of Technology.
Overview
Please see the following documents, which describe the UCX mechanism in more detail:
- Eastham, S.D., Weisenstein, D.K., Barrett, S.R.H., Development and evaluation of the unified tropospheric–stratospheric chemistry extension (UCX) for the global chemistry-transport model GEOS-Chem, Atmos. Env., June 2014. (Article)
- Technical Note: The GEOS-Chem Unified Tropospheric-Stratospheric Chemistry Extension (UCX): Interim Distribution, September 2013 (Article)
--Sebastian D. Eastham 13:08, 03 March 2014 (EDT)
Obtaining the source code
Provisional code
Steven Barrett wrote:
- As a few people have asked for the code for the strat chem version of GEOS-Chem, we've posted it as a simple compressed file here as a temporary location so they can use it right away until it gets integrated into the main code. [Until then], we'll just keep track of any fixes/issues that come up until then.
--Bob Y. 13:44, 30 September 2013 (EDT)
Standard code
UCX has been added to GEOS-Chem v10-01c, which is currently undergoing benchmarking and validiation. It will be included in the GEOS-Chem v10-01 public release, slated for late 2014.
--Bob Y. 14:44, 25 April 2014 (EDT)
Previous issues that are now resolved
The following issues were discovered and corrected when UCX was added into the standard GEOS-Chem code (in version v10-01):
Error in Fast-JX for tropopsheric only simulation
The Fast-JX photolysis package defines 12 wavelength bins that are used for tropospheric chemistry simulations (i.e. without UCX), and 18 wavelength bins for stratospheric chemistry simulations (i.e. with UCX). An bug in the original Fast-JX code caused the cross-sections to be interpolated incorrectly for tropospheric-only chemistry simulations. A full description of this error may be found in this post on our Development of Fast-JX in GEOS-Chem wiki page.
--Bob Y. 14:48, 13 May 2014 (EDT)