The Influence of Daytime Tropical Deep Convective System Initiation on the Diurnal Cycle of Precipitation

Tropical deep convective systems (DCSs) are crucial to Earth’s hydrological cycle via substantial amounts of precipitation. Despite their importance, general circulation models (GCMs) have issues representing their morphological features such as cloud fraction and precipitation. Notably, the diurnal cycle of GCM precipitation over tropical oceans has an overnight peak that is too early and underestimates precipitation during the day, yielding a diurnal cycle that is too large. To better understand the diurnal cycle of tropical oceanic precipitation so that it can be more accurately modeled, the diurnal cycle of DCS initiation and maintenance must be better understood. Focusing on the diurnal cycle of tropical oceanic DCS initiation and its respective contributions to precipitation, this study uses the Tracking Of Organized Convection Algorithm through 3D segmentatioN (TOOCAN) database from 2012 to 2020 to obtain lifecycle information for tropical oceanic DCSs that are matched to precipitation estimates from NASA’s Integrated Multi-satellitE Retrieval for GPM (IMERG) product 3IMERGHH. DCSs are binned by their local solar initiation time to evaluate their morphological characteristics, precipitation contributions, and precipitation statistics. While most previous studies have focused on overnight DCS initiations since they are associated with the peak in precipitation, the focus here will be to evaluate the contributions of the commonly overlooked daytime initiated DCSs to the diurnal cycle of oceanic tropical precipitation.