P-46

Recent development on the global Hybrid 4DVar-LETKF data assimilation system at JMA

Yoichiro Ota (JMA), Takashi Kadowaki (JMA)

Japan Meteorological Agency (JMA) has been developing the hybrid 4DVar-LETKF (Local Ensemble Transform Kalman Filter) system as next generation operational global data assimilation (DA) system. First, the configuration and the analysis and forecast accuracies of the hybrid DA system compared to the current operational DA system will be reviewed briefly. Second, we will present some recent development, mainly focusing on the LETKF in the hybrid data assimilation system. The preliminary investigation on the observation data thinning will be presented. We will show the additional observation data thinning in the LETKF does not significantly degrade the analysis and forecast accuracy of the hybrid 4DVa-LETKF system. We will also present the impact of the initialization procedure using surface pressure tendency analysis and the improvement on the usage of the typhoon-bogus data.