Compound intense warming and precipitation events in the Patagonian Icefields and the Antarctic Peninsula Ice Sheet – Part 1: Event frequency, atmospheric circulation and impacts on glacier surface

Abstract. Intense warming events (IWE) and intense precipitation events (IPE) and their impacts on ice bodies remain overlooked. Using in situ observations, a high-resolution regional circulation model and catalogue of atmospheric river (AR) occurrences, we investigate concurrent IWE over the Patagonian Icefields and IPE over the Antarctic Peninsula Ice Sheet associated with landfalling ARs. Our study focuses on summers (November–March) from 1980 to 2022. We identified 127 compound events linked to a dipole circulation pattern characterized by a ridge over southern South America and a low-pressure system over the Bellingshausen Sea. Both regions experience pronounced surface warming and enhanced melt leading to a negative Surface Mass Balance over the Patagonian Icefields, while positive anomalies still prevailed over the Antarctic Peninsula Ice Sheet were related with increased snowfall associated with AR activity. Surface Energy Balance anomalies were mainly driven by enhanced incoming shortwave radiation over Patagonia but increased longwave radiation over the Antarctic Peninsula, whereas sensible heat flux positively contributed in both regions. These findings highlight the interconnected influence of intense events and AR-driven dipole circulation patterns on the Southern Hemisphere cryosphere, even though individual events exhibit substantial thermodynamic variability and distinct life-cycle characteristics.