关键词: 内蒙古东部牧区, 极端降雪, 海温, Rossby波动

Abstract:

Spatial-temporal characteristics and the formation mechanisms of extreme heavy snow over Inner Mongolia parish were analyzed using techniques of trend analysis and composite analysis, as well as data including NCEP reanalysis data and station snow data in winter over the parish. It was indicated that snowfall over the Inner Mongolia parish appeared to get increased from the west to the east during the past 20 years, with the big value area of snowfall in the mid- east area of Inner Mongolia. During the years of extreme heavy snow in the east parish, there was negative anomaly center in 500hPa height field near Baikal Lake. Code air can be transported to the northeast parish of Inner Mongolia and accumulated when there is a “Ural High(+)-Baikal Trough(-)-Bering Sea Blocking(+)” pattern in 500 hPa height field, which favors the extreme heavy snow. The Arctic areas turned out to be the major moisture sources of heavy snow over east parish of Inner Mongolia. Land-sea thermal difference resulting from Positive SST anomaly of the North Atlantic Ocean becomes Wave-Activity Flux and moves eastward, forming convergence of Wave-Activity Flux and thus leading to the persistence of high press range. Also, the persistence of eastward transmission of Rossby waves was conducive for the formation and persistence of the Ural High, Baikal Trough and Bering Sea Blocking, and the favorable distribution of extreme heavy snow over Euro-Asian Continent.

Key words: eastern Inner Mongolia pasturing area, extreme snowfall, SST, Rossby wave