Hydrostatic and Non-hydrostatic Simulations of the 6 August 1993 Kagoshima Torrential Rain

[摘要] Comparative experiments with real data using hydrostatic and non-hydrostatic models are performed for the torrential rain which occurred on 6 August 1993 in Kagoshima, the southern Kyushu, Japan. A modified version of the three-dimensional anelastic model (Saito, 1994; Kato and Saito, 1995) is used, which is nested with the operational hydrostatic model (the Japan Spectral Model) of the Japan Meteorological Agency. An explicit warm rain process predicting cloud water and rainwater and the moist convective adjustment are individually or conjunctionally employed in the model. The non-hydrostatic simulations of 5 and 10 km horizontal-resolution with a warm rain scheme reproduce continuously heavy rain which corresponds well with the observation. As Kato and Saito (1995) pointed out in a previous comparative experiment of ideal moist convection, the hydrostatic simulation tends to overestimate and overexpand precipitation in comparison with the non-hydrostatic counterpart, and the drag effect of hydrostatic water loading is more significant for convective development than the non-hydrostatic effect. Furthermore, in the 5 km simulations, the hydrostatic approximation greatly overestimates the total precipitation, more than in the simulation of ideal moist convection (Kato and Saito, 1995). From these results, a non-hydrostatic model with hydrostatic water loading is recommended for a high-resolution numerical prediction model.

[学科分类] 大气科学