Structure of Line-Shaped Convective Systems Obliquely Training to the Baiu Front Observed around the Southwest Islands of Japan

Abstract

This study reveals a structure of line-shaped convective systems (LSCSs) observed around the Southwest Islands of Japan on June 10, 2006 using dual-Doppler analyses obtained from two X-band Doppler radars installed on Shimoji and Tarama Islands. Many LSCSs with lengths ranging from 20 km to 40 km form in a band-shaped precipitation system with a length exceeding 300 km along the Baiu front. The alignment directions of the Baiu front and the LSCSs are west-southwest to east-northeast and south-southwest to north-northeast, respectively. Thus, the alignment direction of the LSCSs is oblique to that of the Baiu front, and is parallel to the vertical wind shear vector between 0.5 km and 3 km in altitude.These LSCSs consist of several precipitation cells. The precipitation cells generate only to the south of the southern edge of each LSCS, and move northward and decayed at the northern edge. The pre-existing cells in each LSCS hardly affect the successive generation of new cells. The generation area of precipitation cells coincides with low-level convergence along the Baiu front. The successive generation mechanism of new cells in the observed LSCSs and their structure shown in this study correspond to those in a humid environment, suggested in a previous numerical study.