Authors: Jian Wu Feng Hui Zhi Liu Ji Hua Sun Lei Wang
Publish Date: 2015/08/04
Volume: 126, Issue: 1-2, Pages: 303-312
Abstract
The turbulence spectra and energy budget were investigated based on eddy covariance method over an openwater highland lake Erhai Lake in Southwest China We estimated the annual total evaporation and CO2 emission from the lake and the evaporation trend in the past few decades was also discussed Due to the large thermal inertia of lake water the surface water temperature lagged behind the air temperature Maximum lakeair temperature difference of about 4 °C had been observed in November Water temperature profile measurements revealed that the stratification of lake water was not evident throughout the year The spectra and cospectra of wind speed and temperature roughly satisfied the −2/3 and −4/3 rule in inertial subrange respectively The w spectra were observed to have a larger contribution from higher frequencies than other variables Obvious shifts of spectra and cospectra peaks toward higher frequencies were observed as the atmospheric stratification became more stable The lake acted as a heat sink from March through June and quickly released heat into the atmosphere from September through December Average energy balance closure for the lake was about 80 in 2012 The lake majorly acted as a source of CO2 to the atmosphere but weak sinks of CO2 were observed in the summer and early fall The total annual emission of CO2 was estimated to be 33328 g C m−2 year−1 The annual evaporation over the lake decreased due to the increased amount of low cloud and precipitation with the lower annual evaporation in the 1990s compared to that in the 1980sThis work was supported by the National Natural Science Foundation of China Grant Nos 41030106 and 41021004 and CMA key project GYHY201406001 We thank the staffs from the Yunnan Provincial Institute of Meteorology and Dali National Climatic Observatory for their helps to maintain the measurement and provide historical data
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