1960-2009年石羊河流域气候变化及极端干湿事件演变特征

利用石羊河流域4个气象站1960-2009年逐日气象资料,应用FAO Penman-Monteith模型、相关分析等方法分析石羊河流域气候变化特点。结果表明:①1960-2009年气温、降水及湿润指数均在波动中呈较明显的增加趋势,气温、降水和湿润指数变化倾向率分别为0.338 ℃/10 a、4.791 mm/10 a 和0.006/10 a, 1960年代-2000年代石羊河流域经历了相对冷干-冷湿-暖湿3个阶段,暖湿化趋势明显;②冬季是暖湿化趋势最明显的季节,其次是秋季;③从上游向中下游多年平均湿润指数逐渐减少,湿润指数离散程度由小变大,湿润化速度由快变慢,而增温速度大体上存在逐渐增加的趋势;④1960-2009年石羊河流域极端干旱事件频率在波动中呈减少趋势,极端湿润事件频率却在波动中呈增加趋势,1960年代和1970年代是石羊河流域极端干旱事件持续频发的年代,上中下游不同地区极端干湿事件持续频发的时间存在差异。降水和风速是影响极端干湿事件变化的主要气象因子。在全球变暖背景下,石羊河流域干旱的气候环境有一定的改善。

Temporal and Spatial Characteristics of Climate Change and Extreme Dry and Wet Events in Shiyang River Basin from 1960 to 2009

Based on daily meteorological data from four stations from 1960 to 2009,the article analyzes the temporal and spatial characteristics of the climate change and the extreme arid and wet events of the Shiyang River Basin,using FAO Penman-Monteith model and ArcGIS IDW interpolation.The results show: Firstly,there is an obvious increasing trend,both in the annual humid index and temperature,with the humid index trend rate of 0.006 per 10 a and the temperature 0.338℃ per 10 a,respectively.From 1960s to 2000s,the climate of Shiyang River Basin experienced three stages,namely,comparatively cold dry,cold humid and warm humid.Secondly,the warm humid trend of winter is the most obvious,followed by autumn.Thirdly,the average humid rates gradually decrease from the upper reaches to the middle and to the down reaches,while the warming rates gradually increase.Lastly,frequency of the overall trend of extreme arid events fluctuantly decreased from 1960 to 2009,especially after the 1980s.But,meanwhile,the trend of extreme wet events increased.The period of frequent occurrence of extreme events is from the 1960s to the 1970s.The occurrence of extreme arid and wet events varies in different parts of the Shiyang River Basin.The temperature and wind speed are dominant factors influencing extreme arid and wet events.The arid climatic environment of the Shiyang River Basin has improved on the background of global warming.