Characteristics of Climate Change of the Freezing in Tongren and Disaster Risk Zoning in Recent 60 Years

Based on the long-sequence of observation data from 10 meteorological stations of Tongren in November and March from 1961 to 2008,and the observation data of temperature and precipitation from 92 regional automatic stations of Tongren from 2005 to 2010,the freezing index and spatial-temporal distribution of the freezing are analyed.The result showed that the extra heavy freezing disasters in Tongren happend in 6 years,with the heaviest in 2008.The freezing on the east in Tongren was more serious than the west.The freezing index showed the obvious abrupt changes,with the abrupt change occurred in 1987.While the freezing index flatly changed before it and droped after it.The probability of regional freezing process happening is 71.7 percent in Tongren,with the serious level about 26.7 percent.There are three level freezing process: high,medium and low.