South American Mesoscale Convective Systems: Present and Future Climates

Abstract This study investigates the mesoscale convective systems (MCSs) over South America in a future climate using two distinct modeling approaches: the Weather Research and Forecasting (WRF) regional model with dynamical downscaling and pseudoglobal warming, and the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) global cloud‐resolving model within the Coupled Model Intercomparison Project (CMIP6) High Resolution Model Intercomparison Project (HighResMIP) framework. Results are analyzed in terms of changes in MCS occurrence, precipitation contribution, maximum precipitation rates, and precipitation volume across subregions of South America. MCSs in the future climate tend to exhibit higher maximum precipitation rates and larger precipitation volumes across South America. This tendency toward MCS intensification with increasing temperatures is consistent with previous studies and represents a key aspect of future climate projections. The spatial extent of statistically significant changes is limited, indicating that robust signals common to both models are restricted to specific regions and seasons. Overall, increases in MCS occurrence and precipitation proportion are mainly projected over Northwest South America (NWS) and North South America (NSA), particularly during the austral summer (DJF). Over southern Brazil, they are projected to increase during the austral winter (JJA), suggesting that warmer temperatures may influence the winter climate at the mesoscale level over that region. In contrast, decreases in both variables are found over the South America Monsoon region (SAM), especially during the transition months from dry to wet season (SON) and wet to dry season (MAM).