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Trace gases and aerosols interact with climate and weather by their direct impact on radiation, and by indirect impacts on clouds. In collaboration with atmospheric chemistry and physics modeling groups, GMAO scientists examine a range of problems related to constituents. Middle atmospheric chemistry studies focus on interactions between ozone and climate, examining the recovery of the ozone layer. Tropospheric modeling addresses problems related to climate change, long-range pollution transport and air quality. NASA's satellite data are assimilated to increase understanding of atmospheric composition and, through advanced inversion techniques, to estimate distributions of surface sources and sinks of carbon. There is an emphasis on participation in field missions in conjunction with satellite missions.

Ozone Assimilation develops new statistical techniques and improves the chemistry and transport models used in the assimilation of ozone data. Research is being performed to exploit the value of various types of ozone data from operational and research satellites in advancing our understanding of the ozone distribution in the atmosphere.  The coupled meteorology-ozone assimilation in GEOS-5 enables understanding of interactions between ozone and the circulation, in both retrospective analysis and in real-time analysis and forecasting.

Carbon Data Assimilation exploits NASA’s modeling capabilities and space-based data records to help understand the distribution and cycling of carbon species in the Earth System.  The work utilizes the GEOS-5 atmospheric model and data assimilation system, along with data-constrained models of land and ocean physics and biology to estimate carbon fluxes.  Observations from instruments such as MOPITT, AIRS and eventually OCO are used to constrain atmospheric carbon species.  A long-term goal is to develop a fully coupled atmosphere-land-ocean system for modeling and data assimilation.

Chemistry-Climate Modeling examines coupling between the circulation and composition of the atmosphere.  The GEOS Chemistry-Climate Model (CCM), Version 1, comprises the GEOS-4 GCM and a stratospheric chemistry module developed in the Atmospheric Chemistry and Dynamics Branch at GSFC; this is being used to examine ozone-climate interactions between 1950 and 2100.  Version 2 of the CCM uses the GEOS-5 GCM along with the stratospheric chemistry module, and will be used to examine impacts of volcanic and solar forcing on the ozone-climate system.  Version 3 of the CCM is under development, consisting of GEOS-5 and the tropospheric-stratosphere (COMBO) chemistry code developed in NASA’s GMI project – this will be a tool for examining changes in tropospheric pollutants (ozone, carbon monoxide and aerosols) as emissions change in an evolving climate.

A Constituent Transport Modeling framework is being developed in collaboration with SIVO, in order to provide an environment for chemistry studies that is compatible with the modeling framework used by GEOS-5.  The intention is to provide a flexible environment for chemistry-transport modeling studies with the GMI and GEOS-CHEM chemical packages coupled to transport derived from GEOS-5 meteorological analyses.  The approach adopted will facilitate benchmarking of the off-line transport modules with the computations performed on-line in GEOS-5.