1961—2015年陕北地区降水指数的时空演变规律研究

Study on spatio-temporal evolution characteristics of precipitation indices in the northern Shaanxi from 1961 to 2015

降水指数可有效反映区域洪涝、干旱灾害和水资源条件变化,然而当前与雨日和无雨日相关的指数研究较少。引入雨日和无雨日相关的若干指数,应用于陕北地区降水指数研究,为区域洪旱灾害和水资源演变规律研究及管理提供参考。选用陕北地区25个气象站点1961—2015年逐日降水数据,借助STARDEX研究计划中的8个降水指数,采用线性趋势、多项式拟合、Mann-Kendall趋势检验、ArcGIS空间分析和Hurst指数等方法,对该地区降水指数时空演变规律进行分析。取得主要结论为:(1)与降水量有关指数上升,并具有低-高-低-高的阶段性变化,与无雨日有关的指数上升,并呈现低-高-低的阶段性变化,与雨日有关的指数下降,并呈现高-低-高的阶段性变化;(2)年降水量和雨日相关的指数总体上自南向北递减,无雨日相关的指数总体上自南向北增加,表现出对季风气候的响应;(3)PPWW、PWSAV的下降趋势和PPDD、PDSAV的上升趋势较为显著,而PXCWD和PXCDD的趋势不显著;(4)未来降水量有关指数的上升或下降趋势尚不确定,雨日相关的指数主要维持下降趋势,无雨日相关的指数主要维持上升趋势。因此,研究区未来发生干旱的可能性增加,需要引起重视。

Precipitation indices can well reflect the regional changes of flood and drought disasters and water resources,but the current researches pay less attention to the indices related to rainy days and rainless days.In this paper,several indices related to rainy days and rainless days are introduced and applied to the study of precipitation index change in the northern Shaanxi,providing reference for the research and management on regional changes of flood,drought and water resources.The spatio-temporal evolution characteristics of precipitation indices are investigated based on daily precipitation data of 25 meteorological stations in the northern Shaanxi from 1961 to 2015 with the help of 8 STARDEX precipitation indices,linear trend,polynomial fitting,Mann-kendall trend test,ArcGIS spatial analysis and Hurst exponent methods.The main conclusions are as follows:(1)The indices related to precipitation increases with the changes of low-high-low-high during different stages;the indices related to rainless day increases with the changes of low-high-low during different stages;the indices related to rain day decreases with the changes of high-low-high during different stages.(2)The spatial distribution of precipitation indices shows that AP and the rain-day related indices represent a trend of decreasing from the south to the north,while the rainless-day related indices represent a trend of increasing from the south to the north,indicating a response to the monsoon climate process.(3)The MK trend characteristics of indices related to rainy days and rainless days indicate that the upward trends of PPWW and PWSAV and the downward trend of PPDD and PDSAV are significant,while the trends of PXCDD and PXCWD are not.(4)It is uncertain whether the future precipitation indices will increase or decrease.The indices of rain day will mainly maintain the downward trend,while the indices of rainless day will mainly maintain the upward trend.Therefore,the study area may face a higher probability of drought in the future which needs more attention.