A SCM intercomparison Study on Understanding Diurnal Cycle of Precipitation Over Tropical and Midlatitude Lands

General Circulation Models (GCMs) for weather forecasts and climate simulations continue having difficulties in modeling the diurnal and sub-diurnal precipitation particularly over land. The issue is related to inappropriate representation of the processes that controls sub-diurnal phenomenon like convection, and phenomena with timescales around the order of diurnal, like mesoscale systems. We use a set of single-column models (SCM) from different modeling centers over the world to investigate the interactions between convection and environmental conditions, processes that control nocturnal convections, and the transition from shallow to deep convection in diurnal time scale. The simulations are performed over the research sites at the Southern Great Plains in the U.S. and in the center of the Amazonia in Brazil in which nocturnal convection and afternoon deep convection are major components of summertime precipitation. The goal of this SCM intercomparison study is to understand what processes control the diurnal and sub-diurnal variation of precipitation over different climate regimes in observations and in models and identify the deficiencies and missing physics in current GCMs to gain insights for further improving the parameterization of convection in GCMs.