Comparative Analysis of Two Rainstorms in the Southwest of Hunan Province

• 作者: DAI Jin LV Xiao-hua YANG Ke ZHU He-xiang
• 来源期刊: 气象与环境研究：英文版
• 学科: 地球科学
• 关键词: RAINSTORM Influence system Comparative analysis Water vapor conditions SOUTHWEST jet RADAR ECHO China
• 年，卷（期）: 2012,（12）
• 页码范围: 20-28
• 页数: 9页
• 分类号: P458.121.1

摘要

Using NCEP 1°× 1° reanalysis data within 6 h, conventional observational data, data from regional automatic rainfall stations, satellite cloud pictures and Doppler radar data, we compared the physical conditions, dynamic and thermodynamic characteristics of two rainstorms in the southwest of Hunan Province on May 12 and June 15 in 2011. The results showed that the first process was triggered by strong cold air under unstable potential, while the second process was caused by shear line appearing from the east; during the first process, cold air divided into many parts and moved towards south, rainfall was uniform and lasted for a long time, while rainfall was relatively concentrated and strong, and lasted for a short time during the second process; the peak of K index appeared only during the second process; no sign of heavy rainfall was found from satellite cloud pictures and radar echo pictures during the first process, while obvious cloud cluster and echo ribbons could be found from satellite cloud pictures and radar echo pictures during the second process, which were the sign of heavy rainfall; slow movement of echo or little movement resulted in the second rainstorm, and constant echo intensity was the main reason for the occurrence of the second rainstorm. In addition, there was low-level southwest jet during the two processes, which provided favorable conditions for the transportation of water vapor and energy during the two processes. However, there was a great difference between the two rainstorms in the intensity and thickness of low-level jet, that is, the intensity and thickness of low-level jet during the first process were obviously weaker than these during the second process.