Following the successful experience assimilating real observations on the Earth Simulator, the 4D-LETKF has been applied to JMA's operational global model known as the GSM but with a lower TL159/L40 resolution (currently the operational model resolution is TL319/L40). The 4D-LETKF system is integrated in the same manner as the operational system including the observational quality control. Real observations are assimilated in the period from July 21, 2004 to September 9, 2004, so that the results are verifed in entire August. The system performance will be compared with JMA's operational global 4D-Var system.
Finally, the 4D-LETKF has been modified in accordance with the difference in the lateral boundaries and prognostic variables, so that it was applied to JMA's operational nonhydrostatic mesoscale model (MSM). Following the successful perfect model experiments with 5-km grid spacing and a small computing area around Tokyo, real observations in July 2004 are assimilated with 20-km grid spacing and the same area as JMA's operational MSM. The results will be compared with the operational MSM analysis/forecast system.