Typhoon simulation with the JMA/MRI 20 km mesh high-resolution global spectral model

The Japan Meteorological Agency (JMA), the Meteorological Research Institute (MRI) and the Advanced Earth Science & Technology Organization (AESTO) cooperate to develop a super-high-resolution AGCM (TL959L60;20km mesh), which is used for both weather forecasting and climate research.

In this study, medium-range forecasts were conducted for twelve of tropical storms between 2002 and 2005 over the Western North Pacific Ocean by the 20 km-mesh AGCM. These simulations were statistically verified with the best-track data. They were also compared with the results by the 60 km-mesh AGCM to evaluate differences in resolution.

The 20 km-mesh AGCM was found to predict tropical storms more realistically than the 60 km-mesh AGCM, especially in intensity. When the composite structure of the wind profile were compared, that of inner structure by the 20 km-mesh AGCM is quite realistic. The sharp increse of wind velocity within 100km from the center of the storm is well simulated by the 20 km-mesh AGCM, while the 60 km-mesh AGCM seems to be unable to resolve the structure due to the low resolution.

This study also indicates high-resolution AGCM is necessary for evaluating tropical storms in climate simulations.