Impacts of spatiotemporal variation in lake surface temperature on a convection over Poyang Lake

Abstract

Four experiments, uniform experiment (UF) with a constant lake surface temperature (LST), spatial experiment (SP) with the space change of LST, temporal experiment (TM) with the time change of LST and spatiotemporal experiment (SP-TM) with the space and time changes of LST, were performed to explore the response of a convection over Poyang Lake (PL) in China on 12–13 August 2015 to the time and space variations of LST based on the Weather Research and Forecasting (WRF) model. Simulation results show that the spatiotemporal variation of LST significantly affects the convection. Compared with the observation, the UF and SP simulated convection advances about 3 h, with greater coverage and a more southerly location, while the TM simulated convection also advances about 3 h, with smaller coverage. The SP-TM simulated convection is well consistent with the observation in time evolution, coverage, location and intensity, improving the simulation of the convection greatly. The diagnostic analysis shows that the time and space variations of LST in PL change the atmospheric stability and low-level uplift movement by adjusting low-level air temperature, humidity and wind over PL and its nearby areas, finally affecting the development of the convection. The fact that convection, atmospheric stability and near-surface wind over the lake are sensitive to the spatiotemporal variation of LST strongly suggests the need to monitor and forecast the distribution and time evolution of LST for accurate prediction of convection over PL.