北半球春季雪盖对云南5月降水的影响

Influences of Snow Cover of the Northern Hemisphere on Precipitation of Yunnan Province in May

利用1973-2009年美国大气海洋局环境卫星数据和信息服务部提供的北半球雪盖面积资料、NCEP/NCAR大气环流资料和云南122个气象观测站5月降水资料,对北半球春季雪盖面积与云南5月降水的关系进行研究。结果表明,北半球春季雪盖与云南5月降水密切相关,当北半球雪盖面积增加时,云南西部地区降水偏少、东部地区降水偏多,呈现出东西型的空间分布特征。北半球春季雪盖异常造成云南5月降水异常的物理过程为:当北半球春季雪盖面积偏大时,北极涛动(AO)多呈现负位相分布特征,中纬度出现东风异常,云南西部地区受异常反气旋控制,降水偏少,而其东北部受副热带高压外围的东南暖湿气流影响,降水偏多。由于北半球春季雪盖异常与云南5月降水的相关关系存在较好的持续性,因此,前期春季北半球雪盖面积异常可以作为影响云南5月降水的一个强信号因子,在以后的短期气候预测中加以应用。

With the data of snow cover provided by National Oceanic and Atmospheric Administration/National Environmental Satellite Data and Information Services, Arctic Oscillation, wind field reanalyzed provided by NCEP/NCAR and the precipitation of Yunnan Province from 1973 to 2009, the relationships between the northern hemispheric snow cover in spring and the precipitation in Yunnan Province were analyzed. The study found that there is a closely relationship between spring snow cover in hemisphere and precipitation in Yunnan Province, when the northern hemisphere snow cover area increases, the precipitation in western of Yunnan Province is less, more in eastern Yunnan Province, which presents a parting space characteristic. The physical process that abnormal the precipitation in May in Yunnan caused by anomaly snow cover in the northern hemispheric as follows： When the spring snow cover in hemisphere increases, the AO presents negative phase distribution characteristic and abnormal east wind in middle latitude, the western region in Yunnan Province was controlled by the anticyclone, the precipitation was less, while the northern of Yunnan Province was influenced by the warm and wet southeast air flows of subtropical high peripherals, precipitation was more. The correlation between anomaly spring snow cover in the northern hemisphere and the precipitation in May in Yunnan Province keeps good continuity, therefore, the early anomaly spring snow cover in northern hemisphere can be used as a strong signal factor that affect the precipitation in Yunnan Province and make use of in the later precipitation short-term climate prediction.