乌鲁木齐达坂城谷地一次极端暴雪成因分析  

Causes of an Extreme Snowstorm Process in Dabancheng Valley of Urumqi

作　　者：万瑜[1,2] 胡顺起 李辉 曹兴[5] WAN Yu;HU Shunqi;LI Hui;CAO Xing(Instituteof Desert Meteorology,Chinese Meteorological Administration Urumqi 830002;Xinjiang Meteorological Observatory,Urumqi 830002,China;Linyi Meteorological Administration,Linyi 276004,China;Urumqi Meteorological Administration,Urumqi 830002,China;Xinjiang Meteorological Administration,Urumqi 830002,China)

机构地区：[1]中国气象局乌鲁木齐沙漠气象研究所,新疆乌鲁木齐830002 [2]新疆气象台,新疆乌鲁木齐830002 [3]临沂市气象局,山东临沂276004 [4]乌鲁木齐市气象局,新疆乌鲁木齐830002 [5]新疆气象局,新疆乌鲁木齐830002

出　　处：《沙漠与绿洲气象》2022年第6期85-92,共8页Desert and Oasis Meteorology

基　　金：中国沙漠气象科学基金项目(Sqj2018007);新疆维吾尔自治区科技厅自然科学计划面上项目(2021D01A151)。

摘　　要：2018年3月17—18日乌鲁木齐达坂城谷地出现一次极端暴雪天气,过程累积降雪量达28.7 mm,为冬半年平均降水量的4.35倍。本文利用常规与加密观测、区域自动气象站、FY2G卫星相当黑体亮温(TBB)、NCEP/NCAR再分析等资料,分析此次极端暴雪成因。结果表明:此次极端暴雪天气是以500 hPa中亚低涡、700 hPa气旋性辐合中心及切变线、850 hPa西北气流作为环流背景的低涡型暴雪;水汽主要是地中海、红海的水汽沿着偏西气流经波斯湾—阿拉伯海加强后,随中亚低涡前西南气流输送至暴雪区,另一支为低层西北路径水汽输送,同时由低涡携带的里、咸海水汽,随着系统东移沿其前部的偏西气流输送补充至暴雪区。700~850 hPa达坂城谷地附近为强上升运动区,西北气流受天山阻挡强迫爬升,其较强的上升支气流为暴雪提供了有利的中尺度动力条件;乌鲁木齐至达坂城一线受斜压不稳定增长机制作用,利于暴雪的持续与增强;先后有2个中β云团和1个中α云团东移北上影响造成极端暴雪,强降雪区均位于中尺度云团的北至东北侧TBB等值线梯度最大区。An extreme snowstorm occurred in Dabancheng Valley of Urumqi from March 17th to 18th in 2018,the snowfall was 28.7 mm,which was 4.35 of the average annual precipitation in winter half year.Using the conventional and intensive detecting data,automatic meteorological stations,the FY2G Bold Bright Temperature data and the NCEP reanalysis data,the causes were analized,the results showed that the event occurred under the background with the central Asian Vortex at 500 hPa,a shear line and a cyclonic convergence center at 700 hPa and northerly flows below 850 hPa.The source of water vapor was mainly from the Mediterranean Sea and the Red Sea,which were strengthened by westerly flows through the Persian Gulf-Arab Sea,and transported to the snowfall area by southwesterly flows before the low vortex.The other water vapor was low-level transported along the northwest path.Meanwhile,the water vapor was supplied by westward flows of the vortex from the Caspian Sea and the Aral Sea.The area of strong ascending motion was at 700-850 hPa near Dabancheng Valley.The northwest airflow was forced to climb through the Tianshan Mountains.There existed stronger ascending branch which provided favorable mesoscale dynamic conditions for snowstorm.From Urumqi to Dabancheng,the increasing of baroclinic instability was conductive to the maintaining and strengthening of the snowstorm.Two meso-βconvective clouds and a meso-αconvective cloud sequentially moved northeastward to cause extreme snowfall.Heavy snowfall areas were all located in areas with the maximum gradient of TBB which was from the north to northeast side of the cloud cluster.

关 键 词：达坂城谷地 极端暴雪 环流背景 天气成因 

分 类 号：P458[天文地球—大气科学及气象学]