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Evolution of Melt Pond Fraction and Depth on Multiyear Ice in 2020 from High Resolution Satellite Observations
  • +4
  • Ellen Buckley,
  • Sinéad Farrell,
  • Oliwia Baney,
  • Kyle Duncan,
  • Ute Herzfeld,
  • Thomas Trantow,
  • Matthew Lawson
Ellen Buckley
University of Maryland College Park, University of Maryland College Park

Corresponding Author:[email protected]

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Sinéad Farrell
University of Maryland College Park, University of Maryland College Park
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Oliwia Baney
University of Maryland College Park, University of Maryland, College Park
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Kyle Duncan
University of Maryland, University of Maryland
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Ute Herzfeld
Univ Colorado Boulder, Univ Colorado Boulder
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Thomas Trantow
University of Colorado Boulder, University of Colorado Boulder
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Matthew Lawson
University of Colorado Boulder, University of Colorado Boulder
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Abstract

Observations reveal end of summer Arctic sea ice extent is declining at an accelerating rate. Model projections underestimate this decline and continue to have a broad spread in forecasted September sea ice extent. This suggests some important summer processes, such as melt pond formation and evolution, may not be properly represented in current models. Melt ponds form on the sea ice surface as snow melts, and pools in low lying areas on the sea ice surface. The evolution of the ponds depends on snow depth, ice thickness, and surface conditions. Melt water may spread across a level surface, or be confined to depressions between sea ice ridges. Ponds decrease the albedo of the surface and enhance the positive ice albedo feedback, accelerating further melt. Until recently, Arctic-wide observations of individual melt ponds were not available. ICESat-2, a photon counting laser altimeter launched in 2018, provides high resolution detail of sea ice and snow topography due to its unique combination of a small footprint (~12 m) and high-resolution along-track sampling (0.7 m). The green laser (532 nm) is able to penetrate water, enabling melt pond depth measurements. We have developed methods to track the melt pond surface and bathymetry in ICESat-2 data to determine melt pond depth. We also track melt pond evolution through application of a sea ice classification algorithm to 10 m resolution Sentinel-2 imagery. The combination of these two datasets allows for an evolving, three-dimensional view of the melting sea ice surface. We focus on the evolution of summer melt on multiyear ice in the Central Arctic north of Greenland and Canada in 2020. Our findings are put in context of existing literature on melt pond depth, volume, and evolution. We also discuss our results in relation to the melt pond fraction north of the Fram Strait, where we expect different ice conditions in the vicinity of the 2020 MOSAiC field studies. Observational data products comprising melt pond fraction and pond depth are being developed for public distribution. These products may be of interest to those studying under-ice light and biology, as well as modelers who are interested in understanding the evolution of melt pond parameters for model initialization and validation.