GEOS Composition Forecasts (GEOS-CF)

The GEOS Composition Forecasting (GEOS-CF) system produces global, three-dimensional distributions of atmospheric composition. The spatial resolution is 25km. Using meteorological analyses from other GEOS systems, the GEOS-CF products include a running atmospheric replay to provide near-time estimates of surface pollutant distributions and the composition of the troposphere and stratosphere. A single five-day forecast is generated daily, beginning at 12Z.

example CF map

GEOS-CF was made possible by the inclusion of the GEOS-Chem chemistry model in to GEOS. While building on GMAO’s core capabilities, GEOS-CF also illustrates how collaborative research can lead to the development of new GEOS products. A series of projects funded by NASA has supported GMAO’s collaboration with Harvard University, through which the HEMCO emissions module and the GEOS-Chem code base have been developed (see These code bases are shared in Git repositories, which facilitates common developments by the GMAO and the GEOS-Chem community and simultaneously allows the same code base to be used by the academic research community and the GEOS systems in the GMAO.

GEOS-CF is intended for use by NASA researchers and the broader community, in order to study the interactions among global atmospheric transport, surface emissions, chemical processes, and wet and dry deposition in maintaining the balance of atmospheric composition. Used alongside NASA’s broad range of space-based and in-situ observations, GEOS-CF provides additional tools for understanding processes. The five-day predictions are intended as research datasets, which have numerous applications: to study the science of composition forecasting, to help guide NASA’s field campaigns, and to examine global predictions of surface air quality in context of emissions and transport. Research studies that address applications to human health and other biological processes are also viable.

A priority for future versions of GEOS-CF is to introduce an interface between the GEOS-Chem gaseous chemistry and the GOCART aerosol module used in other GEOS products. Future versions of GEOS-CF will also be more tightly coupled to GMAO’s forefront meteorological assimilation system, GEOS-FP, and will include the assimilation of space-based observations of atmospheric composition, focused especially on NASA’s EOS datasets.

• Questions about GEOS-CF may be sent to our GEOS-CF email list.