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Strong Warming over the Antarctic Peninsula during Combined Atmospheric River and Foehn Events: Contribution of Shortwave Radiation and Turbulence
  • +9
  • Xun Zou,
  • Penny Marie Rowe,
  • Irina Gorodetskaya,
  • David H. Bromwich,
  • Matthew Lazzara,
  • Raul R. Cordero,
  • Zhenhai Zhang,
  • Brian Kawzenuk,
  • Jason M. Cordeira,
  • Jonathan D Wille,
  • F. Martin Ralph,
  • Le-sheng Bai
Xun Zou
University of California, San Diego

Corresponding Author:x4zou@ucsd.edu

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Penny Marie Rowe
NorthWest Research Associates
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Irina Gorodetskaya
University of Aveiro
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David H. Bromwich
Ohio State University
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Matthew Lazzara
University of Wisconsin-Madison
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Raul R. Cordero
USACH
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Zhenhai Zhang
UC San Diego
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Brian Kawzenuk
Scripps Institution of Oceanography
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Jason M. Cordeira
Plymouth State University
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Jonathan D Wille
Université Grenoble Alpes
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F. Martin Ralph
SIO
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Le-sheng Bai
Byrd Polar Research Center
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Abstract

The Antarctica Peninsula (AP) has experienced more frequent and intense surface melting in recent years, jeopardizing the stability of ice shelves and ultimately leading to ice loss. Among the key phenomena that can initiate surface melting are atmospheric rivers (ARs) and leeside foehn; the combined impact of ARs and foehn led to moderate surface warming over the AP in December 2018 and record-breaking surface melting in February 2022. This study uses high-resolution Polar WRF simulations with advanced model configurations, Reference Elevation Model of Antarctica topography information, and surface observed albedo to improve our understanding of the relationship between ARs and foehn and their impacts on surface warming. With an intense AR (AR3) intrusion during the 2022 event, weak low-level blocking and heavy orographic precipitation on the upwind side resulted in latent heat release, which led to a more deep-foehn like case. On the leeside, sensible heat flux associated with the foehn magnitude was the major driver during the night and the secondary contributor during the day due to a stationary orographic gravity wave. Downward shortwave radiation was enhanced via cloud clearance, especially after the peak of the AR/foehn events, and dominated surface warming over the northeastern AP during the daytime. However, due to the complex terrain of the AP, ARs can complicate the foehn event by transporting extra moisture to the leeside via gap flows. During the peak of the 2022 foehn warming, cloud formation on the leeside hampered the downward shortwave radiation and slightly increased the downward longwave radiation.