Analytical and numerical studies on meso-beta scale precipitation bands observed over southern Kyushu on 7 July 1996

Abstract

Three types of meso- β scale bands in a precipitation system over southern Kyushu on 7 July 1996 were analyzed using output from numerical models and observational data from both the Japan Meteorological Agency (JMA) and the Torrential Rain Experiment (TREX). Four meso- β scale regions comprised the precipitation region of the system. Region Ⅰ was characterized by a unidirectional wind environment in which several short convective bands were organized. Convective cells in these short bands displayed characteristics of back-building cells. A hook-shaped band developed over western part of region Ⅰ where intense outflow from another precipitation region intruded. Another meso- β scale band was simulated in precipitation region Ⅲ . In this region, mid-level flow advected convective cells downwind as high equivalent potential temperature air entered the band from its flank, maintaining convection along the whole band length. Comparisons of airflow structures and band shapes suggest that the mid-level wind direction plays a lead role in determining the type of meso- β scale band. In addition, cold air outflow from other meso- β scale precipitation regions can influence band shape.