干旱区生态环境知识资源中心

With the purpose of further understanding the spatio-temporal changes in precipitation, temperature and their possibly changing relationship in the Wei River Basin (WRB), a typical arid and semi-arid region in China, the modified Mann-Kendall (MMK) test method was used to capture their trends at monthly and annual time scales, and the K-means cluster analysis method was applied to divide the whole basin into three homogeneous sub-regions. Furthermore, a copulas-based method was introduced in this study to identify possible inflection points of the relationship between precipitation and temperature in the WRB. Results indicate that: (1) spatially, both annual average precipitation and temperature decreased from southeast to northwest; temporally, for most months, a decreasing trend was found for precipitation while the air temperature in most months has a significantly increasing trend at 99% confidence level at monthly and annual time scales in the WRB; (2) climate warming has less effect on the precipitation structure than that on the precipitation magnitude in the WRB; and (3) overall, the relationship between precipitation and temperature in the whole WRB has no significant inflection point, implying a relatively stable relationship between precipitation and temperature changes. This study provides a new idea and quantitative measure for the identification of inflection points of the relationship between precipitation and temperature.