台风与副高共同影响下的华西秋雨个例分析

Analysis of an Autumn Rain in West China under the Common Influence of Typhoon and Subtropical High

利用常规气象观测资料和再分析资料,采用中尺度分析和物理量诊断方法,对2014年9月持续13 d的连阴雨天气成因进行分析。结果表明,500 h Pa中高纬度大气环流不断经向发展,脊前的西北气流为连阴雨提供了冷空气,副高和台风"海鸥"相继为四川盆地输送暖湿空气;中低层出现西南涡和切变线,有利于降水产生;前期由副高边缘提供水汽输送,动力热力条件较好,产生较强的不稳定性降水;后期由台风外围云系输送水汽,水汽条件相当,但动力热力条件较差,产生较弱的稳定性降水。

Based on the conventional meteorological observations and reanalysis data,we analyzed the cause of continuous rain which lasted 13 days in September 2014 using mesoscale analysis and physical quantity diagnostic methods. The results showed that the atmospheric circulation at middle and high latitudes was developing in merdional direction in 500 h Pa height; the northwest airstream before the ridge provided cold air for continuous rain,and the subtropical high and typhoon Seagulls transport warm and humid air to the Sichuan Basin. The southwest vortex and shear line appeared in middle and lower layers which were conducive to the generation of precipitation. In the early stage,the water vapor was provided by the sub-high edge,and the dynamic and thermal conditions were good,resulting in strong unstable precipitation; in the later period,water vapor was transported by the cloud outside the typhoon,having the same water vapor conditions,but the dynamic and thermal conditions were poor,producing weaker stable precipitation.