Physical controls on half‐hourly, daily, and monthly turbulent flux and energy budget over a high‐altitude small lake on the Tibetan Plateau

Abstract

Precise measurements of evaporation and understanding of the physical controls on turbulent heat flux over lakes have fundamental significance for catchment‐scale water balance analysis and local‐scale climate modeling. The observation and simulation of lake‐air turbulent flux processes have been widely carried out, but studies that examine high‐altitude lakes on the Tibetan Plateau are still rare, especially for small lakes. An eddy covariance (EC) system, together with a four‐component radiation sensor and instruments for measuring water temperature profiles, was set up in a small lake within the Nam Co basin in April 2012 for long‐term evaporation and energy budget observations. With the valuable measurements collected during the ice‐free periods in 2012 and 2013, the main conclusions are summarized as follows: First, a bulk aerodynamic transfer model (B model), with parameters optimized for the specific wave pattern in the small lake, could provide reliable and consistent results with EC measurements, and B model simulations are suitable for data interpolation due to inadequate footprint or malfunction of the EC instrument. Second, the total evaporation in this small lake (812 mm) is approximately 200 mm larger than that from adjacent Nam Co (approximately 627 mm) during their ice‐free seasons. Third, wind speed shows significance at temporal scales of half hourly, whereas water vapor and temperature gradients have higher correlations over temporal scales of daily and monthly in lake‐air turbulent heat exchange. Finally, energy stored during April to June is mainly released during September to November, suggesting an energy balance closure value of 0.97.

Factors controlling evaporation and the CO2 flux over an open water lake in southwest of China on multiple temporal scales

“…However, the correlation coefficient for the relationship between LE and VPD on half‐hourly scale is relatively low. Similar results were obtained over a small high‐altitude lake on the Tibetan Plateau, where a weak relationship between LE and VPD on half‐hourly scale was also reported (Wang et al ., ). Other studies have found a large effect of VPD on the half‐hourly LE over lakes in Germany and Finland (Nordbo et al ., ; Goldbach and Kuttler, ).…”

“…Wang et al . () investigated a small highland lake and found the main driver of heat flux on half‐hourly scales was wind speed, while on daily and monthly scales the water vapour and temperature gradients. A shallow subtropical lake has a small heat capacity and responds quickly to changes in atmospheric forcing, leading to a typically unstable atmospheric boundary layer (ABL) and persistently positive H and LE (Liu et al ., ).…”

Numerical study on the climatic effect of the lake clusters over Tibetan Plateau in summer

“…Recently, with the gradual development of field measurement techniques and computer performances, more observations and simulations have been conducted to study the lake properties and the lake-air interactions over the alpine and cold regions, such as over the TP (Biermann et al 2014;Gerken et al 2013;Lazhu et al 2016;Liao et al 2013;Lu et al 2017;Wang et al 2010Wang et al , 2017Zhu et al 2017). Based on the multi-source sounding data at Lake Nam Co and the MM5 model, Lv et al (2008) revealed that the variations of heat fluxes induced by the lake-land thermal contrast is an important reason for the dramatic changes of the local circulations and mesoscale weather.…”

An integrated investigation of lake storage and water level changes in the Paiku Co basin, central Himalayas

“…Until now, in-situ investigations have only been conducted for a few lakes in the interior TP, e.g. Nam Co (Wang et al, 2009;Zhou et al, 2013;Wang et al, 2017) and Siling Co (Guo et al, 2016;Zhou et al, 2015), which are expanding. In contrast, there have been no detailed in-situ investigations to lakes in the southern TP, where most closed lakes are shrinking.…”