Abstract:

Based on monthly temperature in winter from 20 meteorological stations in Ningxia, monthly sea ice concentration in autumn from the Hadley Centre of UK and monthly atmospheric reanalysis in winter from the NCEP/NCAR from 1961 to 2016, temperature anomaly and its causes in winter of 2016 in Ningxia were studied. The results show that the temperature in winter of 2016 was the highest in the same period since 1961 in Ningxia. In 2016, the 500 hPa zonal circulation was obvious over the middle and high latitudes of Eurasia, and the Ural mountains blocking high was unusually weak, and geopotential height over the mainland China was unusually higher, and position of polar vortex skewed Europe and North America. East Asian winter monsoon index was 1.3 m·s-1, which was the fifth low value since 1961, and Siberia high intensity anomaly was 1.5 hPa, which was the second low value since 2000. The sea ice concentration of  Greenland sea in autumn had a significant influence on temperature in winter in Ningxia. When the sea ice concentration was low, the East Asian winter wind was weaker,the wave pattern labeling “-+-”  on 500 hPa geopotential height in Arctic, Eurasia and Aleutian region enhanced the height difference between the Arctic and Eurasia in the middle and high latitudes, and the westerly airflow over the middle and high latitudes was stronger, and the zonal activity was strengthened. At the same time the weaker Siberian high in the sea level pressure field was not conducive to the Arctic cold air intruding into low latitude region. All above reasons resulted in  higher temperature anomaly in 2016 in Ningxia.

Key words: temperature, circulation, East Asian winter monsoon index, Siberia high, Arctic sea ice

摘要： 利用1961—2016年宁夏20个气象站冬季逐月气温资料，英国气象局哈德莱Hadley中心秋季逐月海冰密集度资料，美国国家环境预报中心/国家大气研究中心（NCEP/NCAR）冬季逐月大气再分析资料，分析2016年宁夏冬季气温异常特征及其成因。结果表明：2016年冬季，宁夏气温创1961年以来同期最高。2016年500 hPa欧亚中高纬地区纬向环流明显，乌拉尔山阻塞高压异常偏弱，中国大陆上空位势高度场异常偏强，极涡偏向大西洋欧洲区和北美大陆；东亚冬季风指数为-1.29 m·s-1，为1961年以来第5低值；西伯利亚高压强度距平为-1.5 hPa，为2000年以来第2低值。秋季格陵兰海冰密集度偏低，导致东亚冬季风偏弱；500 hPa位势高度场上北极、欧亚大陆和阿留申地区呈现“-+-”的波列形态，使得北极与欧亚大陆中高纬地区的位势高度差增强，中高纬西风气流偏强，纬向活动加强；海平面气压场上西伯利亚高压偏弱，不利于北极冷空气向低纬地区侵袭，使得2016年冬季宁夏气温异常偏高。

关键词: 气温, 环流, 冬亚冬季风指数, 西伯利亚高压, 北极海冰