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 builds on a number of activities performed in GMAO’s core developments, most notably the inclusion of aerosols (via the GOCART mechanism) in the GEOS-FP and MERRA-2 products. It also serves as an example of how collaborative research with university groups can lead to new products.

GEOS-CF builds on a number of activities performed in GMAO’s core developments, most notably the inclusion of aerosols (via the GOCART mechanism) in the GEOS-FP and MERRA-2 products. It also serves as an example of how collaborative research with university groups can lead to new 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 http://www.geos-chem.org/). 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.

One priority for future versions of the GEOS-CF system is to develop an interface between the GEOS-Chem gaseous chemistry and a generalized aerosol system. This will enable the GOCART aerosols, used in most GEOS systems, to be used in GEOS-CF; in the longer term this will ease the use of more complex modal aerosol modules alongside the GEOS-Chem gaseous chemistry. A second priority for future versions of GEOS-CF is to introduce the assimilation of space-based observations of atmospheric composition, focused especially on NASA’s EOS datasets.