资源环境科技发展态势分析平台

This study reports the improvements in the diurnal rainfall phase over the Southern Great Plains (SGP) with the Community Atmosphere Model by incorporating two convective initiation designs into the Zhang-Mcfarlane scheme. To capture the convection initiation of the nocturnal rainfall regime, the triggers emphasized the importance of suppression of convective inhibition and identification of elevated buoyancy for initiating convection. Consistent with the single-column study of Wang et al. (2015), the model rainfall bias reduced with an increase in the heavy nocturnal rainfall and with the suppression of the spurious daytime convection in global domain experiments. We found that, with the climate model resolution of 1 degrees, the nocturnal convection over the SGP can be well represented when the destabilization mechanisms of potentially buoyant layer at the low-level troposphere is appropriately captured. Such destabilization is caused by the moisture convergence between the Rocky Mountains-SGP circulations and the uplifted low-level jets from the Gulf of Mexico. Similar improvements are also found in other regions on the lee side of high terrains, such as the Tibetan Plateau.