甘肃中部近66a气候变化特征与旱涝等级响应

The Relation Between Climatic Change Characteristic and Level of Drought and Flood in Central Region of Gansu in the Past 66Years

利用甘肃中部靖远站1950—2015年的降水和气温资料,采用线性趋势回归分析、非参数MannKendall突变检验、Z指数等方法对该地66a的气候变化和旱涝趋势进行了分析。结果表明:(1)近66a研究区年平均气温呈显著上升趋势,66a气温上升了1.175℃。线性增温速率0.178℃/10a,略高于全球平均0.13℃/10a的水平,略低于西北干旱区0.22℃/10a的水平。就季节而言,冬季增温最明显,线性增温速率最大,为0.344℃/10a,春、秋季增温次之,夏季增温不明显。各月气温以2月增温最明显,线性增温速率最大,为0.470℃/10a。(2)年降水季节分配不均匀,降水主要集中在夏季。年平均降水量呈不显著递减,线性倾向率-0.462 9mm/a,春、冬季呈不显著递增,夏、秋季呈不显著递减。(3)以1996年气温突变点为界,突变点前旱涝等级是"正常~涝"为主的格局,突变点后旱涝等级转变成了"旱~正常"为主的格局,地区暖干化趋势明显,重旱和大旱所占比例增加,重、大干旱成灾趋势严重。

With the method of linear trend regression analysis,nonparametric Mann-Kendallmutation test and Zexponent,the climatic change and the trend of drought flood in central region of Gansu was analyzed by using the rainfall and temperature information from 1950 to 2015 in Jingyuan station.The results are as follows.First,the temperature in the region is on the rise in the past 66 years,with a rise of 1.175 degrees centigrade.Linear temperature increasing rate is 0.178 ℃/10 a,a little higher than the global average of 0.13 degrees centigrade/10 and l little lower than the level of 0.22/10 ain the Northwest Arid Area.As far as the season is concerned,the calescence in winter is evident with a maximum calescence rate of0.344 ℃/10 a,the spring and autumn are followed,and the summer is not evident.The calescence in February is the most evident 0.470℃/10 a.Second,annual rainfall is not evenly distributed by seasons,mainly in summer.The annual average rainfall is not significantly diminishing with a linear inclination rate of-0.462 9 mm/a,it is not significantly progressive increase in spring and winter,while not significantly degrease progressively in summer and autumn.Third,1996 is the temperature discontinuity as boundary,before that,level of drought flood is＂normal to flood＂,after that,it is＂drought to normal＂.The region is becoming more and warmer and drought,heavy drought and great drought is becoming more and more frequently,the trend of heavy and great drought is serious.