Analysis of regional temperature variation characteristics in the Lancang River Basin in southwestern China

Temperature variations under climate change have greatly affected regional hydrological processes and agricultural production in the Lancang River Basin, southwestern China. This paper analyzes the spatiotemporal temperature variations in this region from 1960 through 2009 using multiple methods with observed temperature series data from 11 meteorological stations. These methods consist of the rotated empirical orthogonal function analysis (REOF), the Mann-Kendall method, the inverse distance weighting interpolation and the linear regression. The results are as follows: (1) A latitudinal temperature gradient of 4 C degree /degree existed in this region, and a longitudinal temperature gradient of 1.5 C degree /degree was present in both northern and southern areas; the lowest average temperature was observed in the northern part of the basin. (2) Based on spatial patterns from the REOF analysis and regional features including topography, monsoons and climate, four subzones with different temperature variability were designated, and all exhibited significant upward trends in temperature during the studied period. (3) The year 1990 was found to be the abrupt point of the regional temperature variations. The abrupt points in spring and autumn (mainly after 1990) were found several years later than those in summer and winter (mainly before 1990). This research is not only helpful in improving our understanding of the temperature response to global warming in the Lancang River Basin, but also provides a basis for basin management.