Diurnal cycle of precipitation in a climate model

Abstract

An investigation is carried out to study the model capability in resolving the diurnal cycle of June–August rainfall using the Florida State University/Center for Ocean‐Atmospheric Prediction Studies (FSU/COAPS) climate model. The Tropical Rainfall Measuring Mission multisatellite precipitation analysis products are used as the verification data. In order to uncover which model components are more responsible for the diurnal cycle, a number of seasonal (3‐month‐long) integrations are performed by modifying the climate model configurations. It is found that the convective scheme employed is the most crucial component in properly capturing the diurnal cycle of rainfall. A detailed and improved signal of diurnal cycle is obtained in the experiments with a higher horizontal resolution. A negative influence is found when the Community Land Model version 2 as a land surface scheme is used. No additional improvement in the oceanic precipitation diurnal cycle is conferred even if a frequently coupled ocean model is used rather than prescribed weekly sea surface temperatures (SST). This is due to the weak SST diurnal cycle from the ocean model.