近40年黄河源区气候要素分布特征及变化趋势分析

用Mann-Kendall统计检验方法对黄河源区13个气象站点1959—1997年日照、气温、降水、蒸发的分布特征和变化趋势进行了分析,结果表明:近40年黄河源区年平均日照时数表现为微弱的下降趋势,空间分布呈明显的从北部向南部减少的态势,变化趋势从中部向西部、东部、北部逐渐减少;年平均气温呈明显的上升趋势,空间分布规律从西向东、从南向北逐渐增加,变化趋势为中部、南部地区上升趋势最小,北部、东部、西部上升幅度较大;多年平均降水呈较弱的下降趋势,空间分布规律从东南向西北逐渐减少,变化趋势表现为大部分地区降水量呈下降趋势;年平均蒸发量的下降趋势幅度较大,空间分布规律从北部向南部逐渐减少,变化趋势表现为大部分地区呈减少趋势,以北部地区最为明显。另外,本文也应用线性倾向估计方法对黄河源区各气候要素进行了分析,这两种方法得到的结果基本一致。

Spatial and Temporal Characteristics and Change Trend of Climatic Elements in the Headwater Region of the Yellow River in Recent 40 Years

The Mann-Kendall statistic test method is used to estimate the spatial and temporal characteristics and variations trend of sunshine,surface air temperature,precipitation,and evaporation at 13 hydrologic stations in headwater region of the Yellow River from 1959 to 1997.The results show that the trend of sunshine decreased weakly in the study area over the past 40 years,the magnitude of the sunshine decreases from northern to southern parts and the long-term trend decreases from middle to western,eastern,and northern parts.The air temperature remarkably increased over the past 40 years,the magnitude increases from western to eastern,and from southern to northern parts,the long-term trend weakly increases in middle and southern parts,but strongly in northern,eastern,and western parts.The precipitation decreased over the past 40 years,the magnitude of precipitation decreases from southeastern to northwestern parts,the long-term trend decreases in most of the study area.In contrast to the air temperature,the evaporation decreased over the past 40 years,the magnitude decreased from northern to southern parts,the long-term trend decreases in most of the study areas,especially in northern parts.In addition,the linear trends are estimated and the results are briefly presented in this paper.The results which obtained by the two methods coincide well with each other.