GSIOverviewandRecentApplicationatCWB.pptVIP

11/17/2010 NCU (wu) GSI Overview and Recent Application at CWB Wan-Shu Wu NOAA/NWS/NCEP/EMC Overview History Current system Ongoing / future development Recent application at CWB History The GSI system was initially developed as the next generation global analysis system Wan-Shu Wu, R. James Purser, David Parrish Three-Dimensional Variational Analysis with spatially Inhomogeneous Covariances. Mon. Wea. Rev., 130, 2905-2916. Originally based on SSI analysis system Replace spectral definition for background errors with grid point representation Allows for anisotropic, non-homogenous structures Allows for situation dependent variation in errors GSI SSI Gain: freedom in spatial variation of covariance Price: limited freedom in specifying the shape of the error statistics in wave number space. (The limitation is partially over come by applying multiple recursive filters for structure function) In extra-tropics 3D Var in physical space can be as effective as in spectral space. Spatial variation in error stats is beneficial to forecasts in the tropics. Straightforward to apply to a regional domain. History After initial global GSI development, EMC management express desire for single global/regional analysis system Simplify exchange of ideas / developments between global and regional applications Thus, current GSI is an evolutionary combination of the global SSI analysis system and the regional NMM 3DVAR Supports WRF and NCEP infrastructure transition to ESMF History Growing number of collaborators / users NASA: GFSC (GMAO), MSFC FSL, NESDIS, NCAR University of Hawaii, Miami, Oklahoma, Utah, Wisconsin Periodic updates based on submissions from developers Previous update cycle was bi-monthly SVN future updates as System matures Number of change requests increases Analysis (control) vector xa = stream function, velocity potential, surface pressure, virtual temperature, normalized relative humidity, ozone mixing ratio, and cloud condensate mixing ratio SSI