2018年7月19日——8月3日通化市一场持续高温天气过程诊断分析

Diagnosis of a Continuous High Temperature Weather Process in Tonghua from July 19 to August 3, 2018

使用自动气象站观测资料和NCEP再分析资料对2018年7月19日—8月3日通化市一场持续高温天气过程进行诊断分析。结果表明:异常东进偏北的南亚高压同西伸偏北的西太平洋副热带高压相向运动,强度均在同一时期不断变强,同时在通化市及其周边区域上空重叠,它们对此次通化市持续高温天气的形成和增强起到极其重要的作用。对流层高中低大气环流异常特点为高空西风急流显著偏北,异常反气旋性环流对通化市及其周边区域上空造成一定影响,其主要结构为深厚的准正压性,盛行下沉气流,非常不适宜降水天气的发生,进而推动了该地区高温干旱天气的发生。在反气旋异常环流的控制下,通化市及其附近区域水汽通量散度距平场上为显著的正值,这些均突出显示这个区域属于水汽通量异常辐散区,通化市水汽输送异常弱于往年,并且受异常下沉运动的影响,通化市将降水异常偏少,促使高温干旱的出现。

Used the observation data of automatic weather stations and NCEP reanalysis data to analyze the diagnostic exhibition of a continuous high temperature weather process in Tonghua City from July 19 to August 3, 2018.The results showed that the South Asia High moving eastward and northward abnormally and the West Pacific Subtropical High stretching westward and northward are moving in opposite directions, and their intensity wss constantly getting stronger at the same time. At the same time, they overlap over Tonghua City and its surrounding areas. They play an extremely important role in the formation and enhancement of the continuous high temperature weather in Tonghua City. The characteristics of the tropospheric high, medium and low atmospheric circulation anomaly were that the upper westerly jet was significantly northward, and the abnormal anticyclonic circulation does not have a great impact on the air over Tonghua City and its surrounding areas. The main structure was deep quasi barotropic, with the prevalence of downdraft, which is very unsuitable for the occurrence of precipitation weather, thus promoting the occurrence of high temperature and dry weather in the region. Under the control of the anticyclone abnormal circulation, the water vapor flux divergence anomaly field in Tonghua City and its surrounding areas was significantly positive, which highlights that this area belongs to the water vapor flux abnormal divergence area, the water vapor transport in Tonghua City was abnormally weaker than in previous years, and affected by the abnormal sinking movement, Tonghua City will have abnormally less precipitation, promoting the emergence of high temperature and drought.