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Antarctic elevation drives hemispheric asymmetry in polar lapse-rate climatology and feedback
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  • Lily Hahn,
  • Kyle Armour,
  • David Battisti,
  • Aaron Donohoe,
  • Andrew Pauling,
  • Cecilia Bitz
Lily Hahn
University of Washington, University of Washington

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Kyle Armour
University of Washington, University of Washington
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David Battisti
University of Washington, University of Washington
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Aaron Donohoe
University of Washington, University of Washington
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Andrew Pauling
University of Washington, University of Washington
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Cecilia Bitz
University of Washington, University of Washington
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Abstract

The lapse-rate feedback is the dominant driver of stronger warming in the Arctic than the Antarctic in simulations with increased CO2. While Antarctic surface elevation has been implicated in promoting a weaker Antarctic lapse-rate feedback, the mechanisms in which elevation impacts the lapse-rate feedback are still unclear. Here we suggest that weaker Antarctic warming under CO2 forcing stems from shallower, less intense climatological inversions due to limited atmospheric heat transport above the ice sheet elevation and elevation-induced katabatic winds. In slab ocean model experiments with flattened Antarctic topography, stronger climatological inversions support a stronger lapse-rate feedback and annual-mean Antarctic warming comparable to the Arctic under CO2 doubling. Unlike the Arctic, seasonality in warming over flat Antarctica is mainly driven by a negative shortwave cloud feedback which exclusively dampens summer warming, with a smaller contribution from the winter-enhanced lapse-rate feedback.
28 Aug 2020Published in Geophysical Research Letters volume 47 issue 16. 10.1029/2020GL088965