Implementation of the AFWA AGRMET Solar Radiation Scheme in GLDAS
Jesse Meng, Paul Houser, Kenneth Mitchell, George Gayno, Matt Rodell, Urszula Jambor, Jon Gottschalck, Brian Cosgrove, Jon Radakovich, Kristi Arsenault, Michael Bosilovich, Jared Entin, Jeffrey Walker and Hua-Lu Pan
In order to improve our understanding of the space-time structure of the land-atmosphere interaction on a global scale, a high-resolution, near-real-time, Global Land Data Assimilation System (GLDAS) is being developed at NASA's Goddard Space Flight Center and NOAA NCEP. It is within the GLDAS objectives to utilize the remotely sensed and in situ observations to derive a high-resolution global surface solar insolation field for the land surface models forcing. The solar radiation package (Shapiro, 1987) in the AFWA AGRMET model suite is ideal in generating such field in near real-time. This study introduces the methodology and application of the sited solar radiation model. The model is implemented globally on two 1/8 mesh polar stereographic grids, for the northern and southern hemispheres, at about 48 km resolution true at 60 degree latitude. The AFWA RTNEPH 3-hourly cloud analysis (Hamill, 1992) and the SNODEP daily snow analysis will provide input information in near real-time. Those cloud and snow analysis are based on satellite and conventional observations, and are used to calculate the atmospheric transmissivity and reflectivity, and surface albedo. The implementation of using the AGRMET solar radiation in GLDAS will be demonstrated. The comparison between the calculated solar fluxes, the SURFRAD ground observations, the NESDIS GOES satellite estimates, and the NCEP operational regional and global model predictions, will be also presented.