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

The weather research and forecasting model including a one-dimensional thermal diffusion lake model is adopted to investigate the summer climatic effect of the lake clusters over Tibetan Plateau (TP) during 2008–2014 based on two experiments with and without the lakes. Overall, the model can reasonably reproduce the daily variations of lake surface temperature and the spatial patterns of 2 m air temperature (T2m) and precipitation over TP during summer. Sensitivity results show that the effects of TP lakes on the over-lake T2m and precipitation exhibit distinctive seasonal and diurnal features and strong space dependence. Generally, the TP lakes tend to cool the local T2m and enhance the precipitation over the lake and surrounding areas. With the summer advances, the cooling effect of TP lakes weakens while the lake-induced enhancement of precipitation becomes more evident. During daytime, the TP lakes decrease the T2m and suppress the short-duration (≤ 6 h) rainfall in afternoon. However, the TP lakes increase the T2m and strengthen the convective rainfall over the lake and surrounding areas by simultaneously enhancing both short and long-duration (> 6 h) precipitation during nighttime. The lakes over the southeastern central TP (CTP) lead to slight warming and pronounced precipitation increases, while the other lakes in CTP mainly cause significant cooling and suppressed precipitation. Such opposite effects are mainly because the lakes over the western and northeastern CTP hardly produce nighttime warming and the associated circulation changes favorable for the convective precipitation as found over the southeastern CTP, suggesting that the climate effects of TP lakes may be modulated by the lake intrinsic features, local terrain distributions, and background atmospheric circulations.