A044-0002
Evaluation of the GEOS-Chem UCX Stratosphere in the GEOS Composition Forecast System

Tuesday, 8 December 2020
Poster
K. Emma Knowland1,2, Pam Wales3, Lawrence Coy2,4, Krzysztof Wargan2,4, Christoph Keller1,2, Lesley E Ott2, Steven Pawson2 and Sebastian David Eastham5, (1)Universities Space Research Association Columbia, Columbia, MD, United States, (2)NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Greenbelt, MD, United States, (3)Universities Space Research Association Greenbelt, Greenbelt, MD, United States, (4)Science Systems and Applications, Inc., Lanham, MD, United States, (5)Massachusetts Institute of Technology, Laboratory for Aviation and the Environment, Cambridge, MA, United States
Abstract:
The NASA GEOS Composition Forecast (GEOS-CF) system provides 3-dimensional atmospheric composition analyses and forecasts to the public in near-real time at the high spatial resolution of 25 km. While the main focus of this new product is on tropospheric air quality information, the GEOS-Chem chemistry model (v12) used in this system includes the UCX stratospheric chemistry mechanism. Here, we describe the GEOS-CF system and provide comparisons against remote-sensed observations for stratospheric composition, including measurements of HCl, ClO, NO2, and O3. The GEOS-CF nudges the stratospheric ozone towards the GEOS Forward Processing (GEOS FP) assimilated ozone product; as a result the stratospheric ozone analysis in the GEOS-CF agrees well with observations. Additionally, with the inclusion of the GEOS-Chem UCX stratospheric chemistry mechanism in GEOS-CF, 5-day forecasts, especially during the abnormal 2020 NH polar spring, capture the chemical and dynamical changes missed by the GEOS FP system, which tends towards climatology. The GEOS-CF is a new tool for the research community providing near-real time 3-dimensional gridded information on atmospheric composition throughout the troposphere and stratosphere.
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