夏季贝加尔湖南侧环流异常的前兆信号

The precursor of summertime anomalous circulation to the south of Lake Baikal

摘要:

利用1978—2012年NCEP/NCAR逐月再分析资料,对夏季贝加尔湖南侧环流异常的前兆信号进行分析.结果表明:前期冬季印度尼西亚到西太平洋地区对流与夏季贝加尔湖南侧反气旋式环流异常存在一致的变化,为预测夏季贝加尔湖南侧环流异常的前兆信号之一.即当前期冬季印度尼西亚到西太平洋地区对流活动偏强时,夏季对流区北抬至青藏高原西侧,进而有利于贝加尔湖南侧反气旋式环流异常的发生和维持.但是,进一步研究表明,夏季西印度洋对流活动异常将干扰青藏高原及其西侧的对流上升运动对贝加尔湖环流的影响.当夏季西印度洋对流偏强时,前期冬季印度尼西亚到西太平洋对流和夏季青藏高原西侧对流变化表现出不一致.偏强的西印度洋对流将干扰青藏高原及其西侧的对流上升运动对贝加尔湖环流的影响,进而不利于贝加尔湖南侧反气旋式环流异常的形成.当夏季西印度洋对流异常弱时,前期冬季印度尼西亚到西太平洋地区的对流可能引起夏季贝加尔湖南侧环流异常,两者呈现一致的变化;但当夏季西印度洋对流强盛时,将可能改变上述两者的变化关系.

关键词:贝加尔湖南侧反气旋式环流异常;印度尼西亚到西太平洋对流;青藏高原西侧对流;西印度洋对流

Abstract:

Based on the monthly NCEP/NCAR reanalysis data during 1978—2012, this paper studies the precursor of the summertime anomalous circulation to the south of Lake Baikal.Results show that the convection from Indonesia to western Pacific in the preceding winter, consistent with the summertime anomalous anticyclonic circulation to the south of Lake Baikal, is one of the precursors to predict the summertime anomalous circulation to the south of Lake Baikal.When the convection is stronger from Indonesia to western Pacific in the preceding winter, the convection moves northward to the western flank of Tibetan Plateau in summer, which is beneficial to the occurrence and maintenance of the anomalous anticyclonic circulation to the south of Lake Baikal.However, when the convection is stronger in the western Indian Ocean in summer, the convection from Indonesia to western Pacific in the preceding winter is not consistent with that in the western Tibetan Plateau in summer.The stronger convection in the western Indian Ocean weakens the impact of the upward motion in Tibetan Plateau and its western part on the circulation in Lake Baikal, which is against the formation of anomalous anticyclonic circulation to the south of Lake Baikal.Therefore, when the convection is weaker in the western Indian Ocean in summer, the convection from Indonesia to western Pacific in the preceding winter corresponds well with the summertime anomalous circulation to the south of Lake Baikal.When the convection is stronger in the western Indian Ocean in summer, the above relationship will be changed.

Key words:anomalous anticyclonic circulation to south of Lake Baikal;convection in Indonesia and western Pacific;convection in western Tibetan Plateau;convection in western Indian Ocean