1989 Volume 67 Issue 5 Pages 907-924
Japan Spectral Model (JSM) was developed for operational forecast use in JMA. The model is a 19-level spectral limited-area model with a horizontal resolution of 40km. The purpose of the model is to predict meso-α-scale phenomena and fine structures of orographically induced disturbances.
The model predicts quite well the mesoscale structure within a synoptic scale disturbance and the evolution of a mesoscale cloud system associated with a polar low. The model also shows sufficient ability to predict severe rainfalls in the Baiu season.
Forecasts of precipitation show a good performance in spring even in the early hours of the forecast time. However, the scores for the summer season are worse than those for spring. This may be due to the cumulus parameterization scheme used in JSM. Slow spin up of the model is a serious problem in the summer season.
