Skillful Polar WRF Cloud Modeling of a Warm Winter Atmospheric River at the Antarctic Peninsula

Atmospheric rivers are episodic events that can advect relatively large quantities of moisture to Antarctica, contributing to both disproportionate precipitation and melting events. The Year of Polar Prediction, an international effort to improve weather prediction over the southern polar region, presents an opportunity to study the clouds and precipitation associated with winter atmospheric river events. This study uses enhanced surface, profile, and remote-sensing observations from the Antarctic Peninsula (AP) during a Targeted Observing Period around 16 May 2022, when an event occurred with local warming similar to a warm front. We compare regional atmospheric simulations with the polar-optimized version of the Weather Research and Forecasting Model to various in situ and remote-sensing observations. The study emphasizes data from three stations: Escudero, Vernadsky, and Rothera. Mixed-phase clouds were simulated at the three stations, with the precipitation being primarily rain at Escudero and primarily snow at Vernadsky and Rothera. The model produced reasonable simulations of the clouds and precipitation. Furthermore, modeled longwave cloud forcing at Escudero had small errors compared to observed values. A sensitivity test enhancing secondary ice production indicates mixed-phase cloud sensitivity to the Hallett-Mossop process, especially at Rothera.