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Observations of fog-aerosol interactions over central Greenland
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  • Heather Guy,
  • Ian M. Brooks,
  • David D. Turner,
  • Christopher J. Cox,
  • Penny Marie Rowe,
  • Matthew D. Shupe,
  • Von P. Walden,
  • Ryan R. Neely
Heather Guy
University of Leeds

Corresponding Author:[email protected]

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Ian M. Brooks
University of Leeds
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David D. Turner
NOAA Earth System Research Laboratory
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Christopher J. Cox
CIRES/NOAA-ESRL
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Penny Marie Rowe
NorthWest Research Associates
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Matthew D. Shupe
University of Colorado Boulder
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Von P. Walden
Washington State University
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Ryan R. Neely
National Center for Atmospheric Research (UCAR)
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Abstract

Supercooled fogs can have an important radiative impact at the surface of the Greenland Ice Sheet, but they are difficult to detect and our understanding of the factors that control their lifetime and radiative properties is limited by a lack of observations. This study demonstrates that spectrally resolved measurements of downwelling longwave radiation can be used to generate retrievals of fog microphysical properties (phase and particle effective radius) when the fog visible optical depth is greater than ~0.25. For twelve cases of fog under otherwise clear skies between June and September 2019 at Summit Station in central Greenland, nine cases were mixed-phase. The mean ice particle (optically-equivalent sphere) effective radius was 24.0±7.8 µm, and the mean liquid droplet effective radius was 14.0±2.7 µm. These results, combined with measurements of aerosol particle number concentrations, provide observational evidence supporting the hypotheses that (a) low surface aerosol particle number concentrations can limit fog liquid water path, (b) fog can act to increase near-surface aerosol particle number concentrations through enhanced mixing, and (c) multiple fog events in quiescent periods gradually deplete near-surface aerosol particle number concentrations.
21 Feb 2023Submitted to ESS Open Archive
27 Feb 2023Published in ESS Open Archive