The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet
Authors: Wille Jonathan D. , Alexander Simon P. , Amory Charles , Baiman Rebecca , Barthélemy Léonard , Bergstrom Dana M. , Berne Alexis , Binder Hanin , Blanchet Juliette , Bozkurt Deniz , Bracegirdle Thomas J. , Casado Mathieu , Choi Taejin , Clem Kyle R. , Codron Francis , Datta Rajashree , Battista Stefano Di , Favier Vincent , Francis Diana , Fraser Alexander D. , Fourré Elise , Garreaud René D. , Genthon Christophe , Gorodetskaya Irina V. , González-Herrero Sergi , Heinrich Victoria J. , Hubert Guillaume , Joos Hanna , Kim Seong-Joong , King John C. , Kittel Christoph , Landais Amaelle , Lazzara Matthew , Leonard Gregory H. , Lieser Jan L. , Maclennan Michelle , Mikolajczyk David , Neff Peter , Ollivier Inès , Picard Ghislain , Pohl Benjamin , Ralph F. Martin , Rowe Penny , Schlosser Elisabeth , Shields Christine A. , Smith Inga J. , Sprenger Michael , Trusel Luke , Udy Danielle , Vance Tessa , Vignon Étienne , Walker Catherine , Wever Nander , Zou Xun 
Published: November 2023

Abstract
Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. In Part I, we assessed the meteorological drivers that generated an intense atmospheric river (AR) that caused these record-shattering temperature anomalies. Here, we continue our large collaborative study by analyzing the widespread and diverse impacts driven by the AR landfall. These impacts included widespread rain and surface melt that was recorded along coastal areas, but this was outweighed by widespread high snowfall accumulations resulting in a largely positive surface mass balance contribution to the East Antarctic region. An analysis of the surface energy budget indicated that widespread downward longwave radiation anomalies caused by large cloud-liquid water contents along with some scattered solar radiation produced intense surface warming. Isotope measurements of the moisture were highly elevated, likely imprinting a strong signal for past climate reconstructions. The AR event attenuated cosmic ray measurements at Concordia, something previously never observed. Last, an extratropical cyclone west of the AR landfall likely triggered the final collapse of the critically unstable Conger Ice Shelf while further reducing an already record low sea ice extent.

Significance Statement
Using our diverse collective expertise, we explored the impacts from the March 2022 heat wave and atmospheric river across East Antarctica. One key takeaway is that the Antarctic cryosphere is highly sensitive to meteorological extremes originating from the midlatitudes and subtropics. Despite the large positive temperature anomalies driven from strong downward longwave radiation, this event led to huge amounts of snowfall across the Antarctic interior desert. The isotopes in this snow of warm airmass origin will likely be detectable in future ice cores and potentially distort past climate reconstructions. Even measurements of space activity were affected. Also, the swells generated from this storm helped to trigger the final collapse of an already critically unstable Conger Ice Shelf while further degrading sea ice coverage.