Abstract:

Caohai is the largest natural freshwater lake in Guizhou Province as a typical representative of the lakes in the Karst Plateau. In this study, monthly temperature and precipitation data from 1951 to 2016 of Weining were collected and accumulated anomalies analysis, Mann-Kendall test, Sen’s slope estimation method and wavelet analysis were used to reveal the characteristics of the regional climate change. The results showed that the climate of Caohai has developed into a warmer and drier trend from 1951 to 2016, the annual mean temperature increased significantly at the rate of 0.14℃/10 a, the increase rate in different seasons followed the order of autumn > winter > summer > spring, the annual precipitation declined obviously at the rate of 21.46 mm/10 a, the order in different seasons was autumn > summer > spring > winter. The temperature of Caohai showed a downward trend in the 1950s to 1970s and then continued to rise from the point of decadal variability, the beginning of warming in summer and winter was earlier than the beginning of warming in spring and autumn. The abrupt change of annual mean temperature occurred in 2002 to 2003, which were inconsistent in different seasons, and the abrupt change of annual and seasonal precipitation occurred around 1983. The Morlet wavelet analysis showed that the annual average temperature of Caohai had three evident characteristic time scales, with 29, 14 and 6 years, while four evident characteristic time scales in precipitation with 30, 20, 9 and 4 years. These results could provide a scientific basis for ecological and environmental protection and sustainable development of Caohai, and also provide data support for formulating strategies addressing global warming for the lake region on the Karst Plateau.

Key words: climate change, Mann-Kendall nonparametric test, abrupt change, wavelet analysis, Caohai in Guizhou