摘要
选择2008年低温雨雪冰冻灾害和2016年"霸王级"寒潮,利用NCEP/NCAR再分析资料和地面台站资料,采用西伯利亚高压指数、平流层极涡指数与二维阻塞高压指数,分析了两次极端低温过程期间西伯利亚高压、阻塞高压与平流层极涡的组合性异常特征.结果表明,与1970-2005年的气候平均态相比, 2008年西伯利亚高压偏强8.7 hPa,阻塞高压频率偏高50%,极涡偏强190 gpm;2016年西伯利亚高压偏强16.8 hPa,阻塞高压频率偏高约60%,极涡偏强约296 gpm,说明2016年寒潮过程中3种大尺度天气系统的异常比2008年更显著.分析两次极端低温过程中3种大尺度系统的组合性异常特征,发现与1970-2005年气候平均态相比, 2016年寒潮过程期间极涡偏强,北极高空有较强冷空气,北极地表爆发性增温与中高纬阻塞高压的发展,使大量极寒冷的空气在西伯利亚地区积聚,在高空气流的引导下向中国爆发,使中国大部分地区气温短时间内急剧下降; 2008年平流层极涡能量下传,使得阻塞高压长期维持,西伯利亚高压主体也长时间维持,小股冷空气不断东移南下,使中国南部地区维持长时间低温,并与来自南方的暖湿气流交汇,形成长时间的雨雪冰冻天气.
Choosing two typical extreme cold wave events, i.e. the extended snow storm in 2008 and the strong cold wave in 2016, and by using NCEP/NCAR reanalysis data and 671 stations daily surface temperature data in China, the Siberian high index, blocking event index and the stratosphere polar vortex index were calculated to analyze the integrated circulation anomalies of the Siberian high, blocking and polar vortex during extreme cold events. During the event in 2008, the Siberian high was 8.7 hPa stronger, blocking frequency 50% higher and polar vortex 190 gpm stronger than the climatologicalmean. The results showed that, during the extreme low-temperature event in 2016, the Siberian high was16.8 hPa stronger, blocking frequency 60% higher, and polar vortex 296 gpm stronger than the climatological mean, meaning that the anomalies of the three large-scale systems in 2016 were more obvious than those in 2008. As for the integrated circulation anomalies of those three systems during the two events, the results showed that polar vortex was stronger during the event in 2016 than the climatological scenario and there was strong cold air in the Arctic. Explosive warming in the Arctic and the development of the mid-latitude blocking sent heavy cold air to Siberia and airflow at 500 hPa led the cold air to China, making the temperature decrease sharply in a short time. While during the event in 2008, the anomalies of stratosphere polar vortex propagated downward and affected the troposphere. The blocking sustained for a long time, as did the Siberian high. The cold air moved to the south and the east constantly, maintaining a low temperature in southern China for a long time, and leading to cryogenic freezing rain and snow weather, with the help of southern warm and humid air.
作者
李艳
王嘉禾
王式功
Li Yan;Wang Jia-he;Wang Shi-gong(Key Laboratory of Arid Climatic Change and Disaster Mitigation of Gansu Province,College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,China;School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610103,China)
出处
《兰州大学学报（自然科学版）》
CAS
CSCD
北大核心
2019年第1期51-63,共13页
Journal of Lanzhou University(Natural Sciences)
基金
国家自然科学基金项目(41775051)
关键词
低温雨雪冰冻
“霸王级”寒潮
西伯利亚高压
阻塞高压
平流层极涡
cryogenic freezing rain and snow weather
strong cold wave
Siberian high
blocking
stratosphere polar vortex
作者简介
李艳(1983-),女,河南南阳人,副教授,博士,e-mail:liyanlz@lzu.edu.cn,研究方向为灾害气候与干旱气象.
