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Examining Atmospheric River Life Cycles in East Antarctica
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  • Jonathan Wille,
  • Benjamin Pohl,
  • Vincent Favier,
  • Andrew Winters,
  • Rebecca Baiman,
  • Steven Cavallo,
  • Christophe Leroy-Dos Santos,
  • Kyle R Clem,
  • Danielle G Udy,
  • Tessa Rosemary Vance,
  • Irina Gorodetskaya,
  • Francis Codron,
  • Antoine Berchet
Jonathan Wille
ETH Zurich

Corresponding Author:[email protected]

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Benjamin Pohl
CRC / Biogéosciences
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Vincent Favier
Université Grenoble Alpes - CNRS
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Andrew Winters
University of Colorado Boulder
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Rebecca Baiman
University of Colorado Boulder
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Steven Cavallo
University of Oklahoma
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Christophe Leroy-Dos Santos
Laboratoire des Sciences du Climat et de l'Environnementf
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Kyle R Clem
Victoria University of Wellington
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Danielle G Udy
University of Tasmania
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Tessa Rosemary Vance
Antarctic Climate & Ecosystems Cooperative Research Centre
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Irina Gorodetskaya
University of Porto
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Francis Codron
LOCEAN, Sorbonne Université/CNRS/IRD/MNHN
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Antoine Berchet
Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ
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During atmospheric river (AR) landfalls on the Antarctic ice sheet, the high waviness of the circumpolar polar jet stream allows for sub-tropical air masses to be advected towards the Antarctic coastline. These rare but high-impact AR events are highly consequential for the Antarctic mass balance; yet little is known about the various atmospheric dynamical components determining their life cycle. By using an AR detection algorithm to retrieve AR landfalls at Dumont d’Urville and non-AR analogues based on 700 hPa geopotential height, we examined what makes AR landfalls unique and studied the complete life cycle of ARs to affect Dumont d’Urville. ARs form in the mid-latitudes/sub-tropics in areas of high surface evaporation, likely in response to tropical deep convection anomalies. These convection anomalies likely lead to Rossby wave trains that help amplify the upper-tropospheric flow pattern. As the AR approaches Antarctica, condensation of isentropically lifted moisture causes latent heat release that – in conjunction with poleward warm air advection – induces geopotential height rises and anticyclonic upper-level potential vorticity tendencies downstream. As evidenced by a blocking index, these tendencies lead to enhanced ridging/blocking that persist beyond the AR landfall time, sustaining warm air advection onto the ice sheet. Finally, we demonstrate a connection between tropopause polar vortices and mid-latitude cyclogenesis in an AR case study. Overall, the non-AR analogues reveal that the amplified jet pattern observed during AR landfalls is a result of enhanced poleward moisture transport and associated diabatic heating which is likely impossible to replicate without strong moisture transport.
09 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive