Atmospheric buoyancy is likely to influence the amount and intensity of precipitation on the Qinghai-Tibetan Plateau

Abstract

Precipitation over the Qinghai-Tibetan Plateau is complex and primarily affected by the interaction between atmospheric circulation and the complicated topography due to the high altitude. The impacts of the increased altitudes on precipitation over the Qinghai-Tibetan Plateau remain largely unknown. This study designs numerical simulation experiments in the Weather Research and Forecasting (WRF) model, with actual altitudes reduced by 1000 m, 2000 m, and 3000 m, to simulate convective precipitation on the Qinghai-Tibetan Plateau. Furthermore, the effects of high altitude on convective precipitation were revealed by analyzing the buoyancy effect combined with the dynamic and thermal effects on precipitation. The results show that altitude has played a crucial role in modulating both convective precipitation intensity and precipitation amount on the Qinghai-Tibetan Plateau. At high altitudes, the water vapour on the Qinghai-Tibetan Plateau was regulated by the high plateau-induced dynamic blocking effect. The high plateau also affects atmospheric lifting conditions through thermal effects, and the atmospheric pressure at the level of free convection was lower due to the decreased atmospheric density and lower atmospheric pressure, forming less energy and weaker buoyancy effects, resulting in a low intensity of convective precipitation and insufficient precipitation amount on the plateau. In the future, it is necessary to add factors such as atmospheric aerosols and atmospheric chemical processes to improve the simulation accuracy and analyze the process of cloud-forming rain caused by convective precipitation on the high-altitude Qinghai-Tibetan Plateau.