Major features of the latest GEOS-DAS include: high spatial resolution, improved physical parameterizations of the general circulation model (GCM), and an enhanced analysis algorithm called the Physical-space Statistical Analysis System (PSAS). The improvements in the physical parameterizations include a Mosaic land-surface model and a moisture turbulence scheme in the planetary boundary layer. Also, the new GEOS-DAS moisture analysis uses rawinsonde moisture measurements to estimate model bias and to correct the model forecast accordingly. Furthermore, GEOS-DAS incorporates NESDIS and Wentz SSM/I total precipitation water (TPW) into the assimilation. PSAS replaces the optimal interpolation (OI) methodology used in the previous assimilation system (GEOS-1).
The full time series provides 136 physical quantities including wind, temperature, humidity, cloud parameters, total ozone and other important surface parameters. The data have horizontal resolution of 1 degree latitude by 1 degree longitude and 36 vertical pressure levels (except ozone which have a horizontal resolution of 2 degree latitude by 2.5 degree longitude and 42 vertical pressure levels). Time-averaged products are averaged over a 3hour period for single level files or a 6hour period for pressure level files. The data are in HDF-EOS (Hierarchical Data Format – Earth Observing System) format.
The Atmospheric Dynamics Data Support Team (ADDST: http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/atmospheric_dynamics/) at the GES DISC/DAAC will provide support for data distribution, documentation, web-based visualization and analysis tools, and read software for the GEOS-Terra DAS data products. The data can be freely obtained via the EOS Data Gateway (EDG), the GES DISC/DAAC Search and Order WWW interface, or an FTP containing subsetted and reformatted data products.
This paper presents an overview of the GEOS-DAS data and the WWW interfaces for data search, online quality analysis, ordering and subscription services