1961—2010年浙江省冰冻灾害时空特征及其与气象条件的关系

Spatial and temporal characteristics of ice-freezing disasters and its relationship with meteorological conditions from 1961 to 2010 in Zhejiang province

利用1961—2010年浙江省68个站冰冻灾害资料及气温、风速和相对湿度等观测资料,采用线性趋势分析、小波分析和相关分析等方法,统计分析1961—2010年浙江省冰冻灾害时空分布特征,在此基础上分析易引起浙江省冰冻灾害发生的气象条件。结果表明:在时间变化上,1961—2010年浙江省年平均冰冻日数呈显著减少的趋势,并在20世纪80年代末发生突变减少;浙江省冰冻灾害主要发生在12月至翌年2月,其中1月发生最多。在空间分布上,浙江省冰冻日数由西北向东南递减,且在浙江省中北部地区呈舌状分布;对于同纬度地区,天目山附近和浙江省北部的丘陵一带冰冻日数较多,而金衢盆地的冰冻日数相对较少。冰冻日数与最低气温相关最显著,当最低气温为-2℃左右,风速≤4.0 m·s-1,相对湿度为80%左右时,易引起浙江省冰冻灾害发生。

Using daily ice freezing data and corresponding temperature,wind speed as well as relative humidity data at 68 weather stations in Zhejiang province from 1961 to 2010,spatial and temporal distribution characteristics of ice freezing disasters were analyzed using methods of a linear trend analysis,a wavelet analysis and a correlation a-nalysis.Meteorological conditions causing ice freezing disaster were studied.The results show that for temporal variations,annual average number of ice freezing day is in a significantly decreasing trend from 1961 to 2010,and an abrupt change point is observed in the late 1980s.Ice freezing disaster mainly occurs from December and Febru-ary,especially in January.For spatial distributions,the number of ice freezing day is also in a decreasing trend from northwest to southeast,and it is a tonguelike distribution in the middle and northern regions of Zhejiang province. Ice freezing disaster occurs more frequent in Tianmu Mountains and hilly region of northern Zhejiang province than in Jinhua and Quzhou Basin,although these areas are in the same latitudes.The number of ice freezing day is closely related to the minimum air temperature.It is easy to cause ice freezing disaster when the minimum air tem-perature is about -2 ℃,daily mean wind speed is equal or less than 4 m·s^-1 ,and daily mean relative humidity is about 80%.