Climatic characteristics and cause of summer drought in Heilongjiang Province

Based on the actual climate monitoring data during 1954-2009,we analyzed the climate characteristics of drought in Heilongjiang Province,The 1970s and recent 10 years at the beginning of the century,drought has prevailed in the province especially since the year 2000,the drought has happened once every 2 years on average.In most years drought occurred in Lanena event or eastern Pacific equator cold water level phase;the subtropical high is weaker,easterly and north by north part.500hPa circulation characteristics show that east asia region prevails -,+,-anomaly field, the cold air stants to Tamil-Xingdi island of northern Urals,Heilongjiang Province is under control of high ridge of west wind zone or its association with subtropics,and maintains high temperature causing drought.