东亚中纬冬季雪盖异常对初夏环流的影响

用1973～1994年观测资料，研究了东亚中纬冬季雪盖异常对初夏东半球主要流型随季节变化的影响，同时也分析了多（少）雪年份东半球温带地区30～50天低频振荡强度以及夏季中国降水量分布的差异。结果表明，近20年来冬季东亚中纬雪盖强度呈线性增加趋势且迭加较显著的准2年周期变化，它的变化和初夏500hPa低频流型逐候演变之间同时存在线性和非线性相关，并且多雪时欧亚大陆大部分地区30～50天振荡强度增强，而东北亚地区减小。

Influences of the Snow Cover Anomaly During Winter in Mid-latitude Region of East Asia on the Circulations of Early Summer

The influences of the snow cover anomaly during the winter in the mid-latitude region of East Asia on the variations of the dominant low frequency modes with seasons of the Eastern Hemisphere in early summer are studied based on the data from 1973 to 1994, and the differences of the intensity of 30~50 days low frequency oscillation over extratropical Eastern Hemisphere and the summer rainfall over China in snowy and less snowy years are discussed. The interannual variations of winter snow cover at mid-latitude in East Asia appear linear increasing and to have the quasi-biennial oscillation superimposed, and the relationships between its variation and the evolutions of the dominant low frequency modes are linear or nonlinear correlation at the same time. The intensities of low frequency oscillation are stronger for the most regions of Eurasian continents, but weaker in northeastern Asia in snowy years.