塔里木盆地北缘一次局地极端暴雪天气异常机制及成因  

Mechanism and causes of a local extreme snowstorm at the northern edge of the Tarim Basin

作　　者：曲良璐 姚俊强[2] 赵勇[1] 周雪雁 QU Lianglu;YAO Junqiang;ZHAO Yong;ZHOU Xueyan(School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,Sichuan,China;Institution of Desert Meteorology,China Meteorological Administration,Urumqi 830002,Xinjiang,China;Aksu Meteorological Bureau,Aksu 843300,Xinjiang,China)

机构地区：[1]成都信息工程大学大气科学学院,四川成都610225 [2]中国气象局乌鲁木齐沙漠气象研究所,新疆乌鲁木齐830002 [3]新疆阿克苏地区气象局,新疆阿克苏843300

出　　处：《干旱区地理》2023年第5期719-729,共11页Arid Land Geography

基　　金：新疆自然科学基金重点项目(2022D01D86);国家自然科学基金项目(42171038,41875102)资助。

摘　　要：2021年4月2日塔里木盆地北缘拜城县出现突破历史同期极值的灾害性暴雪。利用ERA5高分辨率再分析资料、自动气象站观测资料和FY-2G卫星资料,分析了极端暴雪天气环流异常、多尺度环流特征及物理机制。结果表明:(1)高层伊朗高压及低纬东风气流的异常导致中亚低涡与高原低涡异常结合,加强了低层异常东风气流,东风急流引导南海、孟加拉湾暖湿空气沿河西走廊到达塔里木盆地中部,使得水汽辐合及垂直上升运动加强,在地面辐合线触发下,产生极端降雪天气。地面冷高压稳定维持,导致塔里木盆地持续降温,而拜城位于海拔1000 m以上的浅山区,二者共同作用,造成拜城4月降水相态仍然为雪。(2)垂直位温梯度和西风异常导致湿斜压不稳定发展,形成低层锋生和高层及近地面湿位涡异常,而锋生作用和湿位涡异常又通过垂直运动变化影响降雪的发生发展。对于拜城而言,起决定作用的是中层的上升运动及300~500 hPa的垂直风切变。(3)中尺度云团不断发展并向东北移动经过拜城县上空,增加了降雪持续时间和降雪强度,移动方向和传播方向的一致性则决定了中尺度云团生消演变特征。研究结果可加深对塔里木盆地局地极端暴雪成因的认知,为精确预报、精准服务提供科学支撑。On April 2,2021,a catastrophic snowstorm,which exceeded the historical extreme value,occurred,causing large financial losses in Baicheng County,the northern edge of the Tarim Basin,Xinjiang,China.The hourly European Center for Medium-Range Weather Forecasts fifth-generation(ERA5)high-resolution reanalysis data(0.25º×0.25º),meteorological observation data,and FY-2G satellite data were used to fully analyze the atmospheric circulation anomalies,multi-scale atmospheric circulation characteristics,and physical mechanisms.The following results were obtained:(1)The atmospheric circulation of the snowstorm was typical of a South Xinjiang snowstorm circulation:upper-level South Asian high,subtropical trough,and subtropical westerly jet,mid-level Central Asian vortex,and low-level easterly jet and converging lines combined with the cold high pressure and converging lines at the surface.(2)Extreme snowstorm was caused by the interplay of different-scale atmospheric circulation anomalies.The upper-level anomalies of Iran subtropical high and anomalous easterly airflow at low latitudes led to the anomalous combination of the Central Asian vortex and the plateau vortex at 500 hPa and also generated anomalous easterly airflow at 700 hPa,guiding warm and humid air from the South China Sea and the Bay of Bengal along the Hexi Corridor to the central Tarim Basin,causing water vapor convergence and enhancing vertical upward movement,with the triggering of the surface convergence line,resulting in an extreme snowstorm.A stable maintenance of surface high-pressure systems and cold front produce continuous cooling in the Tarim Basin.Moreover,Baicheng County is located in a shallow mountainous area with an altitude above 1000 m,and the combination produced extreme snowstorm in April.(3)For Baicheng County,the key roles are the upward motion in the middle layer of the troposphere and the vertical wind shear at 300-500 hPa.The vertical profile shows that the level of upward motion of the snowstorm is located at 500-700 hPa,showing me

关 键 词：极端暴雪 大气环流异常 斜压锋生 中尺度云团 塔里木盆地 

分 类 号：P458.121[天文地球—大气科学及气象学]