Cloud Radiative Heating and its Role in Controlling Oceanic Tropical Mesoscale Convective Lifecycles

Cloud radiative heating has long been considered to be a critical part of the diurnal cycle of tropical oceanic convection and is thought to be a strong control on convective organization. Here, we investigate the role of cloud radiative heating on the mesoscale convective lifecycle and how these relationships imprint upon the diurnal cycle of precipitation. To do so, the Weather Research and Forecasting (WRF) model is run over the east Pacific at 3 km resolution and forced by European Center for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis with cloud radiation interactions disabled by making clouds transparent to radiation (e.g., in Clouds On/Off Klima Intercomparison Experiments, or COOKIE). Nocturnal systems are generally shorter-lived when cloud-radiation interactions are disabled. For shorter-lived systems, there is a clear diurnal cycle in precipitation intensity regardless of whether cloud radiation interactions are disabled. However, for longer-lived systems, the diurnal amplitude of precipitation intensity substantially reduces when cloud radiation interactions are disabled. These preliminary results suggest that cloud-radiation interactions are important for the longevity and upscale growth of oceanic mesoscale convective systems, yet they may be less important for deep convective onset and smaller, shorter-lived isolated deep convection.