Numerical Weather Prediction (NWP) at Japan Meteorological Agency (JMA)
JMA started the operation of numerical weather prediction in June 1959. Since then, Performance of NWP models have been advanced thanks to the progress in earth sciences, information technologies such as dramatically increased computer resources and efficient telecommunication systems, and improved observing systems, especially meteorological and earth-observing satellite systems.
JMA currently operates several NWP models to cover various types of forecasts, such as very-short-range prediction of meso-scale disturbances and short-/medium-range prediction of synoptic-scale disturbances. In addition, JMA utilizes ensemble prediction systems and/or a coupled ocean-atmosphere model for the other forecasts including one-week/one-month/seasonal prediction and El-Nino forecasts.
JMA introduced the meso-scale model with higher horizontal resolution, and increased the number of its daily run (operation) in March 2006. As the resolution of the global model was consequentially improved, one-week EPS using the global model products was also improved in November 2007. JMA plans to introduce the EPS for typhoon forecasts within a few years.
Data assimilation systems for NWP are based on the four-dimensional variational (4D-Var) method. The 4D-Var system for the meso-scale analysis and the global analysis were introduced in March 2002 and February 2005, respectively.
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