Characteristics of a Regional Meteorological Drought Event in Southwestern China During 2009-2010
Based on the daily CI drought index from 723 observation stations in China,the characteristics of a severe drought event which occurred in southwestern China from autumn of 2009 to spring of 2010 were analyzed by using the Objective Identification Tech-nique For Regional Extreme Events( OITREE ). The results are as follows:( 1 )According to all the drought events identified by OITREE over the past 50 years,this event was the fifth serious one,that means it was a severe drought event. The drought occurred during August 25th 2009 to April 18th 2010,which went through 237 days. Besides,the drought covered the maximum region of 5 768 200 km2 and the geometric center was located in 33. 72°N,108. 9°E.(2)The impact area of the regional drought event mainly includ-ed Yunnan,southern Sichuan,western Guizhou,Chongqing and western Guangxi,specially,drought intensity was most serious in the border of Yunnan,Guizhou and Guangxi,secondly in the middle and western Yunnan. Above all,the drought in Yunnan was most se-rious.(3)There were four obvious phases in this event. The first phase was from August 25th,2009 to later October 2009,drought began to develop and strengthen continuously,and sustained for two months. The daily impact area and accumulated intensity increased and reached the maximum level among the whole event,and the core regions affected by the drought was located not only in the south-western China but also in the north and south part of China. The second one was from early November 2009 to middle December 2009, drought condition receded while daily impact area shrunk. Drought intensity strengthened again from middle December 2009 to later March 2010,it was notable that the extreme impacted area and accumulated intensity was less than that of the first phase,but the dura-tion was longer. The core region of drought was in southwestern China. Ultimately,the drought condition weakened gradually and then went to the end. Additionally,the spatial distributions of stations,extreme intensity and accumulated intensity on four important turn-ing points could also perfectly showed the processes of severe drought event based on OITREE. In short,the new technique was skillful in identifying the drought event in southwestern China,the identify effect was quite reasonable.
NETL
NSTL
万方数据
维普
