NASA GEOS Composition Forecast Modeling System GEOS-CF v1.0: Stratospheric Composition.
K E Knowland, C A Keller, P A Wales, K Wargan, L Coy, M S Johnson, J Liu, R A Lucchesi, S D Eastham, E Fleming, Q Liang, T Leblanc, N J Livesey, K A Walker, L E Ott, S Pawson
Author Information
K E Knowland: Universities Space Research Association (USRA)/GESTAR Columbia MD USA. ORCID
C A Keller: Universities Space Research Association (USRA)/GESTAR Columbia MD USA. ORCID
P A Wales: Universities Space Research Association (USRA)/GESTAR Columbia MD USA. ORCID
K Wargan: NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA. ORCID
L Coy: NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA. ORCID
M S Johnson: Earth Science Division NASA Ames Research Center Moffett Field CA USA. ORCID
J Liu: Universities Space Research Association (USRA)/GESTAR Columbia MD USA. ORCID
R A Lucchesi: NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA.
S D Eastham: Laboratory for Aviation and the Environment Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA USA. ORCID
E Fleming: Science Systems and Applications (SSAI), Inc. Lanham MD USA. ORCID
Q Liang: Atmospheric Chemistry and Dynamics Laboratory NASA GSFC Greenbelt MD USA. ORCID
T Leblanc: Jet Propulsion Laboratory California Institute of Technology Wrightwood CA USA.
N J Livesey: Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA. ORCID
K A Walker: Department of Physics University of Toronto Toronto ON Canada. ORCID
L E Ott: NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA. ORCID
S Pawson: NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA. ORCID
The NASA Goddard Earth Observing System (GEOS) Composition Forecast (GEOS-CF) provides recent estimates and 5-day forecasts of atmospheric composition to the public in near-real time. To do this, the GEOS Earth system model is coupled with the GEOS-Chem tropospheric-stratospheric unified chemistry extension (UCX) to represent composition from the surface to the top of the GEOS atmosphere (0.01 hPa). The GEOS-CF system is described, including updates made to the GEOS-Chem UCX mechanism within GEOS-CF for improved representation of stratospheric chemistry. Comparisons are made against balloon, lidar, and satellite observations for stratospheric composition, including measurements of ozone (O) and important nitrogen and chlorine species related to stratospheric O recovery. The GEOS-CF nudges the stratospheric O toward the GEOS Forward Processing (GEOS FP) assimilated O product; as a result the stratospheric O in the GEOS-CF historical estimate agrees well with observations. During abnormal dynamical and chemical environments such as the 2020 polar vortexes, the GEOS-CF O forecasts are more realistic than GEOS FP O forecasts because of the inclusion of the complex GEOS-Chem UCX stratospheric chemistry. Overall, the spatial patterns of the GEOS-CF simulated concentrations of stratospheric composition agree well with satellite observations. However, there are notable biases-such as low NO and HNO in the polar regions and generally low HCl throughout the stratosphere-and future improvements to the chemistry mechanism and emissions are discussed. GEOS-CF is a new tool for the research community and instrument teams observing trace gases in the stratosphere and troposphere, providing near-real-time three-dimensional gridded information on atmospheric composition.
