Spatial-Temporal Distribution and General Circulation of Heavy Snow over Tibet Plateau in 1980-2000

Abstract

Based on daily precipitation and snow cover data over Tibet Plateau from 1980 to 2010,the spatial and temporal distribution characteristics,inter-annual variation of heavy snowfall are analyzed. The results show that: There are two high frequent areas,southern slope of Himalayas and northern Tibet. The heavy snowfall happens through the whole year and has bimodal the seasonal distribution,first peak is from March to May and second peak is October. Heavy snowfall processes exhibit an obvious decrease which is about 3. 8 times per 10 years during recent 31 years. The general circulations of heavy snowfall are studied through 48 typical example based on NCEP /NCAR daily geopotential height and wind field reanalysis data. The five main general circulation models are defined named Indian low model which is the main model from October to December,south-north troughs model which is the main model in February and second model in March,Balkhash Lake low model which is the main model in January,Iran high model which is the main model in March and plateau vortex /shear line model which is the main model in April. The southern trough plays the important role in all of the models.