Extreme weather events in Urumqi and their relation with regional climate change

Based on the daily weather observation data from 1976 to 2007,the change of extreme weather events and its possible relationship with the climate warming in Urumqi was analyzed by the trend analysis,correlative analysis and wavelet analysis methods.The results show that the low temperature,strong wind and thunderstorm events have a obviously decreasing trend in the last 32 years;sandstorm and heavy fog events have a decreasing trend to different extent,but the torrential rain,heavy snow event and high temperature events have a increasing trend in the past 32 years.The heavy fog events,strong wind,low temperature,high temperature and thunderstorm events have a remarkable annual change;but the annual changes of the torrential rain,heavy snow,sandstorm and hailstone events are inconspicuous.Climate warming in Urumqi region shows asymmetry characterizes,the autumn,spring,winter minimum temperature increase significantly;all extreme synoptic event which were researched in this paper have evident variation periods.There are high correlation between the annual average temperature and some extreme weather events such as high temperature,low temperature and sandstorm.There is a close relationship between the changes of the extreme weather events which have better correlation with annual average temperature and the regional climate warming.The regional climate warming and the change of climate variability may lead to the extreme weather events.To understand the law of appearances of extreme weather events plays an important role for urban disaster prevention reduction.The mechanism of the hazard events needs further research.