冬季东亚大槽振幅指数及其与东亚冬季地面气温的联系

Amplitude index of the East Asia Trough and its relationship with winter surface temperature in East Asia

利用NCEP/NCAR月平均再分析资料中的500 hPa位势高度数据,基于振幅定义了冬季(12-2月)东亚大槽振幅指数I_(EAT),分析了东亚大槽与东亚冬季地面气温之间的联系.结果表明,I_(EAT)能够反映东亚大槽的强度变化.1948-2018年I_(EAT)总体有微弱的增大趋势,表明东亚大槽强度增大.I_(EAT)与东亚沿岸地区的冬季气温呈显著负相关,当I_(EAT)偏大(小)时,东亚沿岸地区冬季气温偏低(高).I_(EAT)偏大的年份,地面西伯利亚高压偏强和850 hPa经向风异常偏大是东亚沿岸地区冬季地面气温异常偏低的主要原因.

Using NCEP/NCAR monthly mean reanalysis data of 500 hPa geopotential height,this study defined the amplitude index of the winter East Asian Trough I_(EAT).The relationship between the East Asian Trough and the winter surface temperature in East Asia was analyzed.The results showed that the amplitude index of I_(EAT)could depict the strength of the East Asian Trough.From 1948 to 2018,I_(EAT)presented a slightly increasing trend,indicating that the intensity of the East Asian Trough increased.There was a significant negative correlation between I_(EAT)and the winter temperature in the coastal areas of East Asia,and when I_(EAT)was larger(smaller),the winter temperature was lower(higher)in the coastal areas.In winters with a larger I_(EAT),the abnormally enhanced Siberian High and the abnormal 850 hPa meridional wind were the main reasons for the lower winter surface temperature in the coastal areas of East Asia.