PNNL

Abstract

Multiple independent mesoscale convective systems (MCSs) can occur closely in space and time, subjecting common geographic regions to multiple precipitation events over short periods. Motivated by an earlier study highlighting significant hydrological impacts of clustered MCSs in the US, we extend the analysis to seven global continental MCS hotspots using a 20-year global MCS dataset. Our findings reveal that (1) 40-80% of MCSs occur in clusters, depending on the region; (2) clustered MCSs exhibit larger rainfall areas and higher rainfall-per-unit-area, with the strongest impacts observed in Argentina and India; and (3) clustered MCSs contribute increasingly to 24-h and 72-h precipitation extremes across all regions. Our results underscore the critical role of clustered MCSs in driving hydrological extremes over global land regions and highlight the need to better understand how their formation mechanisms differ from non-clustered events across the globe.