P-40

Applying the four-dimensional Local Ensemble Transform Kalman Filter to the Nonhydrostatic Icosahedral Atmospheric Model NICAM

K. Terasaki (RIKEN), T. Miyoshi (RIKEN)

We developed the NICAM-LETKF system but did not apply the four-dimensional treatment of observations. Here, the existing 3-D NICAM-LETKF is upgraded to treat asynoptic observations appropriately and is tested with real conventional observations. The ensemble size is fixed at 40, and the results show that the analysis is improved in the upgraded 4-D NICAM-LETKF compared to the previous 3-D version. The improvement reaches 30% around the tropopause to the lower stratosphere.