Research On Response Process Of Surface Water Temperature Of Dianchi Lake Under Climate Warming

Lake Surface Water Temperature is an important physical property that affects the aquatic environment of the lake,and it plays an important role in the water chemical and ecological processes in the lake.At the same time,the surface water temperature of the lake has a significant impact on the environment of the lake basin,especially urban lakes will play an important role in climate regulation of the cities where the lake basin is located,and affect the living comfort of urban residents.It is instructive to explore the changing trend and characteristics of the water temperature on the surface of the lake,It is also of great significance for improving the overall water ecological environment of the lake.Among them,plateau lakes have a more sensitive response to climate warming due to their special geographical location.And the change of the water temperature on the surface of the lake will have a very important impact on the climatic diversity,species diversity and cultural diversity of the plateau and mountainous regions.Therefore,carrying out the analysis of the spatiotemporal process of the lake surface water temperature change is the basis for controlling and improving the lake's water ecological environment and regional ecological environment.Dianchi Lake,a typical plateau urban lake in this study selection area,is the research area.Taking the Landsat series data from 1988-2018 and the Dianchi watershed temperature data from 2001-2018 and MOD11A2(including day and night)product data as research data.Regression analysis,mutation analysis,Morlet wavelet analysis,and correlation analysis were used to analyze trends,significance analysis,mutation analysis,and cycle analysis of air temperature and surface temperature of Dianchi Lake in the past 20 years.Then,the kriging interpolation method was used to analyze the spatial distribution and change characteristics of Dianchi Lake surface water temperature at different time scales.Finally,the Pearson correlation coefficient was used to analyze the correlation between the temperature of Dianchi Lake water temperature and the surface water temperature of Dianchi Lake.The results show that the water area of Dianchi Lake has undergone two processes of decreasing and increasing since 1988,and tended to be relatively stable in 2016.From 2001 to 2018,the temperature of the Dianchi Lake Basin generally showed an upward trend.The average annual temperature increase rate of the Dianchi Lake basin was about 0.03 ° C / year,and a sudden change occurred in 2008.Except for a slight downward trend in winter,the seasonal average value showed a warming trend in spring,summer,and autumn;the monthly average value decreased for 5 months,and the rest of the months showed an upward trend.The surface water temperature of Dianchi Lake increased from day to night during 2001-2018(day: +0.12 ° C / year,night: +0.09 ° C / year),and both increased significantly(day: P <0.001,night: P <0.05).The average surface water temperature of Dianchi Lake during the day and night in spring and summer showed a non-significant increase.The average surface water temperature of Dianchi Lake during the day and night increased significantly.During the day and at night,there are the average monthly surface water temperature of Dianchi Lake showed a downward trend(small in total).The mutation test analysis showed that the average annual temperature of Dianchi Lake during the day was 2011 and the night was 2008.There were abrupt changes in the surface water temperature of Dianchi Lake during the day and night seasons in spring,summer,autumn and winter.The annual average temperature of the surface of the Dianchi Lake has quasi-two oscillations of cold-warm alternation,and the average monthly temperature of the surface of the Dianchi Lake has quasi-17 oscillations of cold-warm alternation.There are basically consistent periodic fluctuations on the same time scale during the day and night.During the day,the average annual and seasonal average surface water temperature distribution of Dianchi Lake is similar,showing a downward trend from the lake's coast to the center of the lake,and vice versa at night.The correlation analysis results showed that the annual average surface water temperature of Dianchi Lake during the day had a low correlation with the average annual temperature,and the average annual surface water temperature of Dianchi Lake at night had a high correlation with the annual average temperature,which were all non-significant.The correlation between the seasonal average Dianchi surface water temperature and the seasonal average temperature is better than the annual average correlation,and the correlation in autumn is significant.The monthly average surface water temperature of Dianchi Lake has the highest correlation with the monthly average temperature,and it is significant.This research has certain theoretical contribution and engineering significance to the related departments to control the pollution of Dianchi Lake water environment and improve the water ecological environment of Dianchi Lake.