Trend and extreme occurrence of precipitation in a mid‐latitude Eurasian steppe watershed at various time scales
Trend and extreme occurrence of precipitation in a mid‐latitude Eurasian steppe watershed at various time scales
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DOI：
10.1002/hyp.10054
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发表时间：
2014-10
影响因子：
3.2
通讯作者：
Xixi Wang;Xiaomin Yang;Ting-xi Liu;Fengling Li;R. Gao;L. Duan;Yanyun Luo
中科院分区：
文献类型：
--
作者：
Xixi Wang;Xiaomin Yang;Ting-xi Liu;Fengling Li;R. Gao;L. Duan;Yanyun Luo
阶跃变化的混杂效应使常用的趋势分析方法（如Mann-Kendall检验技术）的平稳性假设失效，因此以前的研究未能解释检测到的趋势与观测到的大降水异常之间的不一致。本研究的目的是（1）制定一个趋势分析方法，考虑由于阶跃变化的非平稳性，（2）使用这种方法来检测中国北方中纬度欧亚草原流域降水的趋势和极端事件，（3）研究流域径流如何响应降水趋势。结果表明，年降水量在1995年前后经历了一个边际阶跃。1994年以后显著的年下降趋势主要是由于夏季降水量减少;其他季节没有明显的降水趋势。在月尺度上，1994年以后的7月降水量呈现明显的下降趋势，而其他月份的降水量没有变化趋势。湿日数的百分比也经历了一个步骤跳1994年左右的一个显着的下降趋势，但降水强度没有表现出一个步骤的变化，也没有任何显着的趋势。然而，研究流域的低频和高频降水事件发生在1994年之后比之前更频繁;可能是气候变化的结果或指标。为了应对这些降水变化，研究流域观测到的年降水量小于300 mm、介于300 mm和400 mm之间以及大于400 mm时，降水径流关系明显不同。版权所有© 2013 John Wiley & Sons，Ltd.
The confounding effects of step change invalidate the stationarity assumption of commonly used trend analysis methods such as the Mann–Kendall test technique, so previous studies have failed to explain inconsistencies between detected trends and observed large precipitation anomalies. The objectives of this study were to (1) formulate a trend analysis approach that considers nonstationarity due to step changes, (2) use this approach to detect trends and extreme occurrences of precipitation in a mid‐latitude Eurasian steppe watershed in North China, and (3) examine how runoff responds to precipitation trends in the study watershed. Our results indicate that annual precipitation underwent a marginal step jump around 1995. The significant annual downward trend after 1994 was primarily due to a decrease in summer rainfall; other seasons exhibited no significant precipitation trends. At a monthly scale, July rainfall after 1994 exhibited a significant downward trend, whereas precipitation in other months had no trend. The percentage of wet days also underwent a step jump around 1994 following a significant decreasing trend, although the precipitation intensity exhibited neither a step change nor any significant trend. However, both low‐frequency and high‐frequency precipitation events in the study watershed occurred more often after than before 1994; probably as either a result or an indicator of climate change. In response to these precipitation changes, the study watershed had distinctly different precipitation‐runoff relationships for observed annual precipitations of less than 300 mm, between 300 and 400 mm, and greater than 400 mm. Copyright © 2013 John Wiley & Sons, Ltd.