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 3 (GEOS-CCMv3), consists of GEOS-5 and the tropospheric-stratosphere (COMBO) chemistry code developed in NASA's GMI project - this model is being used in collaboration with scientists in the Atmospheric Chemistry and Dynamics Branch (ACDB), to examine changes in tropospheric pollutants (ozone, carbon monoxide and aerosols) as emissions change in an evolving climate. Older versions of the CCM are still in use. Version 1 comprises the GEOS-4 GCM and a stratospheric chemistry module developed in the ACDB; this is being used to examine ozone-climate interactions between 1950 and 2100. Version 2 uses the GEOS-5 GCM along with ACDB's stratospheric chemistry module, and has been used to examine impacts of volcanic and solar forcing on the ozone-climate system.