Local Ensemble Transform Kalman Filter with Nonhydrostatic Icosahedral Atmospheric Model NICAM

Two versions of the local ensemble transform Kalman filter (LETKF) are implemented with the Nonhydrostatic Icosahedral Atmospheric Model (NICAM): one with the grid conversions between NICAM's icosahedral grids and LETKF's longitude-latitude grids to take advantage of the existing LETKF code (LL-LETKF), and the other without the grid conversions by modifying the I/O of the LETKF code (ICO-LETKF). The real conventional observations from the NCEP PREPBUFR data are assimilated. The results show that both systems perform stably and that ICO-LETKF successfully reduces the computational time and interpolation error due to the grid conversions. We also attempt to assimilate the ATOVS satellite radiances and also the precipitation data from the Global Satellite Mapping of Precipitation (GSMaP). This presentation will include the most recent results from the NICAM-LETKF developments.->