宁夏冬季气温变化与大气环流异常的关系

利用1961~2015年冬季(12月到次年2月)宁夏20个气象站月平均气温资料,NCEP/NCAR发布的500 h Pa位势高度场和海平面气压场,200 h Pa、850 h Pa风场月平均再分析资料,运用线性倾向估计、M-K法及合成分析等方法,在研究宁夏冬季平均气温的年际变化及年代际变化特征的基础上,分突变前后的冷、暖期时段进一步分析大气环流场不同影响因子与宁夏冬季气温异常的关系,揭示宁夏冬季气温异常的成因。结果表明:(1)宁夏冬季平均气温由冷变暖的趋势非常显著,在1985年之前为冷期,1985年以后为暖期;冬季平均气温年代际变化在20世纪增暖趋势显著,21世纪后上升趋势趋于平缓。(2)不仅500 h Pa位势高度场的乌拉尔山高压脊和西太平洋副高是影响宁夏冬季气温异常的主要系统,海平面气压场的西伯利亚高压也是影响宁夏冬季气温异常的关键系统;高低空的偏北气流和偏南暖湿气流异常流场也对宁夏冬季气温变化造成一定影响。

Relationship between the variation of winter temperature in Ningxia and atmospheric circulation anomalies

Based on the monthly temperature data of 20 meteorological stations in Ningxia and the NCEP/NCAR monthly mean reanalysis data of 500 hPa geopotential height field and sea level pressure ,200 hPa and 850 hPa wind field in winter (December to February) from 1961 to 2013, by applying the methods of linear tendency estimate, the M-K method and synthetic analysis,on the study of the interannual and inter-decadal variation characteristics of winter average temperature in Ningxia, the relationship between the different influencing factors of the atmospheric circulation field and the winter temperature anomalies in Ningxia were further analyzed during cold and warm periods before and after the mutation point, to reveal the cause of Ningxia winter temperature anomalies. The results showed that: Firstly, trend from cold to warm of winter average temperature in Ningxia was very significant, the winter average temperature in Ningxia before 1985 was a cold period,while after 1985 it was a warm period; The warming trendency of the inter-decadal variation of winter average temperature was significant in the 20th century, however in the 21st century the rise was leveling off. Secondly, for winter temperature anomalies in Ningxia district, not only the high-pressure ridge of 500 hPa geopotential height field over Ural Mountains, and west pacific subtropical highSwere the main affecting system,but also Siberian high pressure of sea level pressure field; Abnormal field of the north-deflected airflow and the south-deflected warmSand moist airflow of high and low level also had an influence.