利用ERA-Interim资料,采用改进的变形欧拉平均方法对1979-2011年剩余环流季节内时空结构转换及其演变特征进行了分析。结果表明:(1)150 hPa附近4-8月剩余环流上升中心发生了整体向北移动的趋势,而9月至次年2月则表现为整体向南的移动,并且6-8月和9-11月的移动较为明显,分别向北和向南移动了3.168°和2.277°。(2)对流层内的剩余质量输送显著增强,但是热带环流上升区以及穿越对流层顶进入平流层的输送存在着减弱的趋势。(3)两半球高纬度100 hPa附近从最低平流层向下输送的质量通量以及热带对流层顶附近向上输送的质量通量在各季节年代际变化中基本都是减弱的,仅在6-8月和9-11月北半球向下质量通量出现了增强。
Using the European Center for Medium Range Weather Forecasts Interim (ERA-Interim)data,temporal-spatial structural switch and evolution characteristics of the residual circulation derived from the improved transformed Eulerian-mean equation in the different seasons during 1979-2011 were analyzed.The results show that:(1)The center of the residual circu-lation upwelling in 150 hPa tends to shift toward the north from April to August,and reaches to a souther location from Sep-tember to February next year during 1979-2011.The change in June-August (JJA)and Septermber-November (SON)are most obvious;it extends 3.069 degree toward the north in JJA and 2.376 degree toward the south in SON,respectively.(2) The residual circulation in the troposphere observably strengthens in the different seasons during 1979-2011,but it weakens in the circulation upwelling area near the tropical and near tropopause.And,(3)both of downward mass flux in the high latitudes of the two hemispheres and upward mass flux in the tropics near 100 hPa almost all weaken in the different seasons during 1979-2011,except for downward mass flux in the Northern Hemisphere during JJA and SON.