Climate Characteristics of Hail Disasters in Aletai of Xinjiang
Based on the meteorological data from eight observation stations in the Aletai region from 1954 to 2010,the characteristic of hail disasters was analyzed by using mathematical statistics method and Mann-Kendall test.Results show that the interannual variation of hail had a 3-5 years oscillation cycle and presented decreasing trend on the whole.After the year of 1996,the hail frequency de-creased significantly,which might be related to the abrupt change of climate.The seasonal variation of hail disasters was obvious with high frequency in summer and little occurrence in winter.The hail duration generally remained about 10 min,and the duration less than 5 min,10 min accounted for 61.2% and 89.3%,respectively,while the duration more than 30 min accounted only for 1.5%. The hail occurred more in Jimunai,Aletai,Qinghe and less in other counties,and little in Fuhai.The occurrence of hail was closely related to topography and altitude,with the increasing of altitude,the hail times presented logarithmic increasing trend.The gradient of the west of Aletai,Buerjin towards to Jimunai was the largest,and there was high risk in the north and east region of Altai Mountains, while less risk in the central and southern area.