Exploration on the Changes and Causes of Lake Surface Temperature and Lake Heatwave in Qinghai Lake from 1980 to 2022 

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  • 1. State Key Laboratory of Cryospheric Science and Frozen Soil EngineeringNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000GansuChina
    2. Qinghai Lake Comprehensive Observation and Research StationChinese Academy of SciencesGangcha 812300QinghaiChina
    3. College of Petrochemical EngineeringLanzhou University of TechnologyLanzhou 730050GansuChina

Online published: 2025-05-20

Abstract

Under the influence of global warmingthe surface temperature of lakes on the Qinghai-Xizang Plateaualong with the total duration and mean intensity of lake heatwaveshas exhibited significant increases. These trends amplify the susceptibility of lake surface temperatures to heating during thermal stratification periodsaccelerating summer warming rates and potentially inducing surface hypoxia. Previous studies analyzing lake heatwave characteristics have predominantly focused on spatially averaged metrics across broad regionsleaving the specific heatwave dynamics of Qinghai Lake poorly characterized. To address this knowledge gapthis study integrates in-situ observations of Qinghai Lake's water temperature and surface temperaturemeteorological data from Gangcha StationMODIS land surface temperature productsthe Third Pole high-resolution near-surface meteorological forcing datasetTPMFD),and simulations from the one-dimensional Freshwater Lake ModelFLaketo investigate long-term changes in surface temperature and heatwave characteristics of Qinghai Lake from 1980 to 2022. Through correlation analysis and detrended decomposition methodsthe driving mechanisms underlying these changes were systematically elucidated. The research shows that:(1The air temperaturespecific humidity and wind speed of TPMFD reanalysis data are highly correlated with those observed by Gangcha meteorological stationand the biasesBIASand root mean square errorsRMSEare small. The correlation coefficients of the two data are 0. 960. 84 and 0. 74respectivelyand the BIAS is 0. 55 ℃0. 00068 g·g-1 and -0. 31 m·s-1respectively. The RMSE is 0. 59 ℃0. 00069 g·g-1 and 0. 38 m·s-1respectively. The change rate of the air temperature in TPMFD0. 48 °C·10a-1is close to that of the observed air temperature0. 44 °C·10a-1. The variation rate of the specific humidity in TPMFD0. 0001 g·g-1·10a-1is consistent with the observed variation rate. The variation rate of the wind speed in TPMFD-0. 1 m·s-1· 10a-1is slightly smaller than that of the observation-0. 25 m·s-1·10a-1. Moreoverthe change rates of the air temperaturespecific humidityand wind speed in both TPMFD and the Gangcha Meteorological Station have passed the significance test at the 95% confidence level. The simulated water temperature and lake surface temperature of Qinghai Lake have a very good correlation with the in-situ observed water temperature and lake surface temperature of Qinghai Lakeand the biases and root mean square errors are relatively small. The longterm sequential simulated lake surface temperature also has a good correlation with the MODIS surface temperatureand both the BIAS and RMSE are within a reasonable range. The correlation coefficients between the simulation results and the three kinds of observations are 0. 990. 96and 0. 98 respectivelythe BIAS are 0. 25 °C-0. 1 °Cand 0. 87 °C respectivelyand the RMSE are 0. 58 °C2. 65 °Cand 2. 20 °C respectively.2From 1980 to 2022both the characteristics of the lake surface temperature and lake heatwaves in Qinghai Lake showed a significant increasing trendp<0. 05. The frequency of lake heatwaves fluctuated between 0 and 6 times. The total number of days with lake heatwaves each year increased significantly. The total number of days in 2022 reached 150 days. The mean lake heatwave duration in most years exceeded 10 days per occurrence. The maximum lake heatwave duration in 2022 even reached 76 daysand the mean lake heatwave intensity increased significantly. The intensity levels of heatwaves in Qinghai Lake in 2016 and 2022 were in a "severe" statewhich is two orders of magnitude stronger than the multi-year average intensity level"moderate" level.3Air temperaturespecific humiditydownward long-wave radiationdownward short-wave radiationand air pressure are positively correlated with the increase in the simulated lake surface temperature. Moreoverthey are positively correlated with the increase in the total days of lake heatwaves. Furthermorethey are positively correlated with the enhancement of the mean intensity. However wind speed is negatively correlated with the increase in the simulated lake surface temperature and positively correlated with the increase in the total days of lake heatwaves and the enhancement of the mean intensity. The meteorological factors that positively contribute to the increase in lake surface temperaturefrom largest to smallestare air temperature23. 83%),specific humidity20. 52%), wind speed 16. 05%),downward long-wave radiation 14. 79%),and downward short-wave radiation 10. 68%. The meteorological factors that positively contribute to the increase in the total days of lake heat‐ waves are air temperature37. 54%),wind speed35. 86%),specific humidity30. 03%),downward longwave radiation28. 27%),and downward short-wave radiation27. 72%. The meteorological factors that positively contribute to the enhancement of lake heatwave intensity are air temperature13. 25%),wind speed 13. 07%),specific humidity12. 35%),downward long-wave radiation11. 05%),and downward shortwave radiation10. 98%. Air pressure has an inhibitory effect on the increase in lake surface temperaturethe total days of lake heatwavesand the mean intensity.

Cite this article

WANG Tiantian, WEN Lijuan, XIE Gang, WANG Mengxiao, HAN Tianxiang, CHEN Shiqiang, YU Tao . Exploration on the Changes and Causes of Lake Surface Temperature and Lake Heatwave in Qinghai Lake from 1980 to 2022 [J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00062

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