Subtropical PRECIpitation extremeS and their atmospheric drivers in a changing climatE

Objective

Extreme precipitation events frequently cause flooding with catastrophic impacts. Counterintuitively, such extreme events are particularly impactful in regions with an arid climate, which are home to more than a third of the world’s population. While theory, observations, and models generally suggest amplifying precipitation extremes under climate warming, these changes remain uncertain in the dry subtropics. Specifically, current climate model simulations are hampered by (i) the poor representation of highly complex precipitation processes in coarse-resolution models, (ii) natural variability masking anthropogenically forced trends, and (iii) the regionally varying response of atmospheric circulation patterns to climate warming. PRECISE aims to unravel the climate model representation and future changes of precipitation extremes in arid subtropical regions through the lens of their driving atmospheric processes. This objective will be achieved by applying cutting-edge diagnostics of a key atmospheric process - Rossby wave breaking - to available model output from two classical global climate model large ensembles and three new global storm-resolving model simulations. First, I will identify biases in these processes in model output for the present-day climate compared with observations. Second, I will quantify the future changes in these extreme events in climate projections. Third, I will examine how local precipitation extremes at hourly timescales and associated convective processes respond to climate warming. This project focuses on precipitation extremes and their future changes in societally vulnerable yet scientifically overlooked regions. PRECISE combines the researcher’s expertise in subtropical precipitation processes and the supervisor’s experience in studying weather extremes and their future changes using climate models.