关键词: 重庆市, 森林火险, 盛夏, 春季:火险等级

Abstract:

Based on the daily precipitation，maximum temperature，relative humidity and wind speed at 34 weather stations in Chongqing during 1961－2007，the homochronous monthly reanalysis data from NECP/NCAR and forest fire data from the Headquarter of Chongqing Forest Fire Prevention during 1970－1998，the variation characteristics of forest fire was investigated by defining the meteorological environment index of the forest fire danger．And on this basis the atmospheric circulation features of the typical years with high forest fire danger were analyzed further in spring and hot summer．The results displayed that the temporal and spatial characteristics of the forest fire in Chongqing was obvious．The peak periods of forest fire occurred in hot summer ( from August to September) and spring ( from February to April) ，which accounted for 78% of the annual fire．The number of forest fires was the most in August，which accounted for 18% of the annual total number．The forest fires occurred mostly at afternoon when temperature is higher．The atmospheric circulation anomaly of the 500 hPa geopotential height field in typical years of high forest fire danger in spring was negative in Ural Mountains，Lake Baikal and Okhotsk Sea，and that was positive in Sichuan Basin．Thus the cold air was accumulated in the middle and high latitudes，which resulted in the location of the main frontal zone of weather system to northward． In hot summer，the large－scale circulation pattern of the 500 hPa geopotential height anomaly field in typical years of high forest fire danger was negative in Lake Baikal and Okhotsk region，and that was positive in Korean Peninsula which indicated location of the western Pacific subtropical high was to the north．The high forest fire danger was easy to happen．

Key words:
Chongqing, forest fire danger, high summer, fire danger rating