Impact of climate warming on the surface water temperature of plateau lake

Lake surface water temperature (LSWT) is a vital indicator in evaluating the ecological environment and has a direct or indirect impact on regulating physical, chemical, and ecological processes of lakes. Changes in LSWT have a huge impact on the water quality, ecosystem function, and biome composition of the entire lake. In this study, we selected Dianchi Lake as the research area, the monthly average LSWT data collected at the monitoring station from 1998 to 2009 were used as the calibration dataset. The error analysis dataset is the average annual temperatures of the Dianchi Lake extracted from MODIS remote sensing images from 2001 to 2017. The daily average LSWT of Dianchi Lake was estimated by the air–water model and the historical changes from 1980 to 2017 of the LSWT were reproduced. The research draws a conclusion that the LSWT of Dianchi Lake has been greatly affected by air temperature over the past 37 years. LSWT and the annual average air temperature correlation coefficient were R > 0.9. Both the air temperature and LSWT assumed an increasing tendency. The annual average LSWT increased with the rate of 0.36 °C/decade, and the annual average warming rate of the air temperature was 0.47 °C/decade. The monthly average LSWT and air temperature showed a significant correlation at a confidence interval of α = 0.001. The LSWT of Dianchi Lake increased significantly in February, March, and December. The periodicity of the seasonal mean air temperature change was consistent with that of the LSWT in Dianchi Lake. The relative lag of the thermal response of the LSWT to climate warming was also observed. This study fills in the gaps in the long-term sequence data on the LSWT of Dianchi Lake and reveals the effect of climate warming on the LSWT of low-latitude plateau lakes.