Atmospheric River‐Cyclone Events Disrupting an Antarctic Peninsula Field Campaign: Dynamics, Mesoscale Wind Amplification, and Long‐Term Context

Abstract

Extreme weather in the Antarctic Peninsula arises from interactions among large‐scale circulation variability, atmospheric rivers (ARs), extratropical cyclones, and complex coastal terrain, yet the linkages across these scales remain insufficiently resolved. We examine an austral‐summer storm sequence in early January 2025, when three storms within 8 days disrupted a glaciological field campaign in the northern Antarctic Peninsula, forcing repeated shutdowns and transfer of personnel. Reanalysis diagnostics show that recurrent Bellingshausen Sea cyclones, together with a blocking ridge over the Atlantic‐Scotia sector, sustained poleward flow and repeatedly directed ARs toward the Peninsula. Wave decomposition indicates that the hemispheric circulation was largely described by combined wave‐1 and wave‐3 components. Active Madden–Julian Oscillation phases 6‐7 in late December, followed by phases 8‐1 in early January, coincided with a transition toward negative Southern Annular Mode conditions. Lagged climatological composites support this sequence as a plausible preconditioning pathway for enhanced meridional moisture transport toward the Peninsula. High‐resolution Polar‐WRF simulations show that these synoptic conditions produced strong terrain‐modified wind amplification over only a few kilometers, with wind speeds exceeding 20 m s ⁻¹ at the campsite while nearby coastal areas remained partially sheltered. Forecast diagnostics indicate scale‐dependent predictability, with the broader storm and moisture environment largely captured for the third storm, whereas local near‐surface winds remained more uncertain. In the longer record, detected warm‐season AR‐affected days increase more clearly than cyclone counts, suggesting that moisture‐laden, successive storms and terrain exposure may become increasingly important contributors to Antarctic Peninsula operational risk.