Multiscale Controls on Oceanic Tropical Precipitation in Observations and Models

Precipitation over tropical oceans is modulated by processes that span a wide range of spatiotemporal scales. Recent studies have shown that precipitation is strongly influenced by both large-scale equatorial waves and by the mesoscale organization of convection. Using high-resolution observational satellite products and reanalysis, we characterize the statistical importance of each of these processes in modulating the intensity and frequency of strongly precipitating systems. We find that the most heavily precipitating systems tend to occur in regions of wave-scale deep vertical ascent. However, we also find that heavily precipitating systems are associated with a greater degree of mesoscale convective organization even in regions not undergoing large-scale ascent. We additionally use output from a state-of-the-art global cloud-permitting model to examine how large-scale equatorial waves interact with mesoscale tropical convection. We find that this class of model can capture mesoscale circulations associated with larger-scale convective variability. This study hopes to contribute to the discussion surrounding the relationship between tropical moist cumulus convection and large-scale atmospheric structures, and further our understanding of how these “scale interactions” project onto changes in the tropical hydrologic cycle.