青藏高原及周边地区极端降水天气事件及其基于自组织特征映射方法的天气背景分型  

Extreme precipitation weather events in the Qinghai Tibet Plateau and its surrounding areas and weather background classification based on self-organizing feature mapping

作　　者：辛鹏超 央珍 王其伟[1] 张熠[1] XIN Pengchao;YANG Zhen;WANG Qiwei;ZHANG Yi(Key Laboratory of Mesoscale Severe Weather/College of Atmospheric Sciences,Nanjing University,Nanjing 210023,China;Navigation Meteorological Division,China Civil Aviation Administration of Tibet Autonomous Region,Lhasa 850707,China)

机构地区：[1]南京大学大气科学学院/中尺度灾害性天气教育部重点实验室,南京210023 [2]中国民用航空西藏自治区管理局航行气象处,拉萨850707

出　　处：《气象科学》2024年第1期94-105,共12页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(91937301,41775054);国家重点研发计划资助项目(2017YFC1501603)。

摘　　要：利用2008—2014年中国自动站与CMORPH降水产品融合资料和NCEP再分析资料,基于自组织特征映射方法对青藏高原及周边地区的6 h极端降水天气进行了统计分析。发现6 h极端降水的高值和高频次主要分布在青藏高原西南部和东南部,以及东南侧的四川盆地和南侧沿喜马拉雅山至横断山脉一带。6 h极端降水在高原西南部多发生在14时(北京时,下同),在东南部多发生在20时,而在四川盆地和南侧主要发生在08时。采用自组织特征映射方法将2008—2014年高原及周边地区6 h分辨率的天气背景分为5类,类型I至类型V体现了从夏季—春秋—冬季的渐变,6 h极端降水天气事件发生比率依类递减。高原上总的极端降水主要来自类型I的高原极端降水,类型II及以下的高原极端降水落区逐类缩减并趋于沿冈底斯山零散分布。对比各类型的天气背景发现,高原上类型II及以下的动力强迫较类型I逐渐增强,但是暖心、湿度和对流有效位能等有利热力条件却依类明显缩减,使得高原极端降水落区依类迅速缩减。有利热力条件的分布与大范围极端降水的落区有很好的对应关系,热力条件减弱后,动力条件的增强及其与高原复杂地形的相互作用是导致零散极端降水的重要原因。四川盆地和高原南侧的对流有效位能明显高于高原内,高原在周边的强迫抬升易于触发对流不稳定,释放较高的对流有效位能,形成较强和较频繁的极端降水天气事件。This paper makes a statistical analysis of the 6-hour extreme precipitation weather events on the Qinghai Tibet Plateau and its surrounding areas based on self-organizing feature mapping,by using precipitation products from observations of China automatic stations and CMORPH and NCEP reanalysis data during 2008-2014.It is found that the high value and frequency of 6-hour extreme precipitation are mainly distributed in the Southwest and Southeast of the plateau,the Sichuan Basin on the southeast side of the plateau and the area along the Himalayas to Hengduan Mountains on the south side of the plateau.The 6-hour extreme precipitation mostly occurred at 14∶00 BST in the southwest of the plateau,at 20∶00 BST in the southeast of the plateau,and at 08∶00 BST in the Sichuan Basin and on the south side of the plateau.Using the self-organizing feature mapping method,the weather background in 6-hour interval over the plateau and its surrounding areas from 2008 to 2014 is divided into five types.The weather background types fromⅠtoⅤreflect the gradual change from summer to spring/autumn to winter,and the occurrence rate of 6-hour extreme precipitation weather events decreases as the weather type number increases.The total 6-hour extreme precipitation on the plateau mainly comes from that of typeⅠ,and the area of 6-hour extreme precipitation decreases gradully from typeⅡto higher type number and tends to be scattered along the Gangdise mountain.Comparison of the weathe types shows that the dynamic forcing becomes stronger from typeⅠto higher type number,while the favorable thermal conditions of warm center,humidity and convective available potential energy are significantly reduced,this results in the obvious reduction of extreme precipitation areas on the plateau type by type.The distribution of favorable thermal conditions has a good relationship with the larger area of 6-hour extreme precipitation.As the thermal conditions weaken,the stronger dynamic conditions interacting with the complex terrain are imp

关 键 词：青藏高原 极端降水 天气型 自组织特征映射 

分 类 号：P426.6[天文地球—大气科学及气象学]