The use of dual—Doppler radar data in the study of 1998 meiyu frontal precipitation in huaihe river basin

Abstract

During the Meiyu period in June and July of 1998, intensified field observations have been carried out for the project “Huaihe River Basin Energy and Water Cycle Experiment (HUBEX)”. For studying Meiyu front and its precipitation in Huaihe River basin, the present paper has performed analysis on the middle and lower level wind fields in the troposphere by using the radar data obtained from the two Doppler radars located at Fengtai district and Shouxian County. From June 29 to July 3 in 1998, the continuous heavy precipitation occurred in Huaihe River basin around Meiyu front. The precipitation process on July 2 occurred within the observation range of the two Doppler radar in Fengtai district and Shouxian County. The maximum rainfall of the Meiyu front was over 100 mm in 24 h, so it can be regarded as a typical mesoscale heavy precipitation process related to Meiyu front. Based on the wind field retrieved from the dual Doppler radar, we find that there are meso-γ scale vertical circulations in the vertical cross-section perpendicular to Meiyu front, the strong upward motion of which corresponds to the position of the heavy rainfall area. Furthermore, other results obtained by this study are identical with the results by analyzing the conventional synoptic data years ago. For example: in the vicinity of 3 km level height ahead of Meiyu front there exists a southwest low-level jet; the rainstorm caused by Meiyu front mainly occurs at the left side of the southwest low-level jet; and the Meiyu front causes the intensification of the low-level convergence in front of it.