Observed and Simulated Lake Effect Precipitation Over the Tibetan Plateau: An Initial Study at Nam Co Lake

摘要

Thousands of lakes are located on the Tibetan Plateau. However, few studies examine the impacts of these lakes on local climate. To investigate lake effect precipitation over the plateau environment, we take Nam Co Lake as a case study, due to its large size and the availability of in situ observations. Using the Weather Research and Forecasting (WRF) model, the impacts of Nam Co Lake on downwind precipitation events (i.e., the generation and causes) are studied quantitatively. First, we compare meteorological station observations downwind of the lake with observations from other nearby stations. In total, four stations are located around Nam Co Lake in different directions, and these stations accurately represent the spatial distribution of observed precipitation. The largest amount of precipitation is observed at Nam Co station (downwind) in October, and this precipitation amount is more than twice that observed at the other three stations. Second, simulations are carried out using the WRF model, and the results show that WRF model accurately captures the precipitation events that occurred at Nam Co station in October 2006. Finally, the WRF_lake and WRF_nolake simulations, which do and do not include the lake, respectively, are carried out using the WRF model. Nam Co Lake caused an increase in precipitation of up to 70% downwind of the lake on 24 October 2006. The simulation results also show that the lake caused an increase in precipitation of up to 60% over the lake's area and downwind of the lake in October of 2006.