HAPpy Hour Seminar : Future Rainfall Extremes in the Tropics in Convection-Permitting Models

Abstract: The tropics frequently experience rainfall extremes due to tropical cyclones, mesoscale convective systems (MCSs), and isolated convection that are dictated by the interaction of large-scale dynamics with local-scale processes. Using convection–permitting models allows us to better understand these multi-scale interactions giving rise to rainfall extremes and to more accurately capture rainfall processes. Here, we use the MPAS-A model to simulate rainfall extremes in two understudied regions of the world- Africa and Puerto Rico- in a current and future climate. Over Africa, we use MPAS-A and the Pseudo-Global Warming (PGW) method to simulate how MCSs could change by the end-of-century. Future changes in CAPE, CIN, and relative humidity influence the change in MCS characteristics, with distinct differences over water and land. Over Puerto Rico and the Caribbean region, we use MPAS-A to directly downscale 0.25 degree global climate model (GCM) data to a 3-km grid-spacing to study how different storm types change by mid-century. Here, we show that differences in storm types leading to extreme rainfall events over Puerto Rico differ in the early versus late rainy season. Both simulations highlight the utility of using convection-permitting models to study future rainfall extremes in tropical regions.