Verification of the MRI-Nonhydrostatic-Model Predicted Rainfall during the 1996 Baiu Season

Abstract

The verification of the rainfalls predicted by the 10 km-resolution non-hydrostatic mesoscale model of the Meteorological Research Institute(MRI-NHM)was performed during the 1996 Baiu season. The verification was also compared with the results of the 10 km-resolution hydrostatic Regional Spectral Model(RSM) of the Japan Meteorological Agency(JMA). The warm rain scheme that explicitly predicts cloud water and rainwater is employed in MRI-NHM, while two parameterized convective schemes are used in conjunction with large scale condensation in RSM. The MRI-NHM greatly overestimated the maximum of precipitation intensity and the precipitation area of heavy rainfall(≥20 mm h^-1), slightly underestimating the area of weak rainfall(∼1 mm h^-1). The statistical scores showed that the MRI-NHM more accurately predicted the rainfall over 10 mm h^-1 than the RSM, while the prediction of MRI-NHM is not as good as that of RSM for less than 5 mm h^-1 rainfall. The MRI-NHM could hit almost half of the rainfalls over 20 mm h^-1. The rainfall was more accurately predicted in the southern region of Kyushu than in the northern region. This is resulted from the difference between the heavy rainfall formation mechanism in the northern and southern regions of Kyushu.