渭河流域近50年来气候变化趋势及突变分析

基于渭河流域1958—2008年的主要气象数据,采用Mann-Kendall和R/S方法,对渭河流域降水和气温2个要素的时间序列进行趋势分析,在此基础上采用Mann-Kendall法对其突变点进行检验.结果显示:1)渭河流域年均气温在时间上呈现出明显上升的趋势,其中春季、秋季、冬季的上升趋势非常显著;在空间上则表现为中游地区气温最高;从整个流域Hurst指数分析看,未来渭河流域年平均气温仍将持续升高,但变异程度不显著.2)渭河流域的年降水量在时间上呈现出一定的减少趋势,其中春季和秋季降水显著减少,冬季降水量增加;在空间上表现为从上游到下游逐渐增加;从Hurst指数看,渭河流域的降雨序列处于弱变异状态,未来的降水变异不显著.3)对渭河流域近50a的气温和降水进行突变分析,大部分站点气温突变出现在20世纪90年代,之后显著变暖,与突变前相比较有明显差异;降水量突变点较多,每个年代都有不同程度上的突变,20世纪60年代和90年代尤为显著.

CLIMATE CHANGE AND MUTATION ANALYSIS IN WEIHE RIVER BASIN IN THE LAST 50 YEARS

Meteorological data from 1958—2008 in Weihe River were used to analyze time series trend of precipitation and temperature in Weihe River basin,by the Mann-Kendall and R/S method,Point mutations were then calculated.It was found that the average annual precipitation on Weihe River showed a rising trend from upstream to downstream.The annual precipitation decreased during the last 50 years,but with no statistical significance.The decreasing trend of precipitation was significant in spring and autumn;but a significant increase was seen in winter.Hurst index was found to be 0.49,showing a weak variation,future precipitation variation being insignificant.It was also found that the average annual temperature in the middle reaches were maximal in the Weihe basin.A marked upward trend was found by time series method,significant in spring,autumn,winter,but not significantly in summer.Viewed from the Hurst exponent,future annual average temperature was likely to continue to rise.Analysis of temperature and precipitation mutation revealed complex changes in precipitation,every 50 years showed a different degree of mutation,this being particularly significant for the 60’s and 90’s.Compared with complex precipitation change,temperature for each site mutation occurred only once in the 90s,and it was significantly warmer after temperature mutation.