Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

Charalampos Charalampidis, Dirk van As, William T. Colgan, Robert S. Fausto, Michael Macferrin, Horst Machguth

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

We present in situ firn temperatures from the extreme 2012 melt season in the southwestern lower accumulation area of the Greenland ice sheet. The upper 2.5 m of snow and firn was temperate during the melt season, when vertical meltwater percolation was inefficient due to a ~5.5 m thick ice layer underlying the temperate firn. Meltwater percolation and refreezing beneath 2.5 m depth only occurred after the melt season. Deviations from temperatures predicted by pure conductivity suggest that meltwater refroze in discrete bands at depths of 2.0-2.5, 5.0-6.0 and 8.0-9.0 m. While we find no indication of meltwater percolation below 9 m depth or complete filling of pore volume above, firn at 10 and 15 m depth was respectively 4.2-4.5°C and 1.7°C higher than in a conductivity-only simulation. Even though meltwater percolation in 2012 was inefficient, firn between 2 and 15 m depth the following winter was on average 4.7°C warmer due to meltwater refreezing. Our observations also suggest that the 2012 firn conditions were preconditioned by two warm summers and ice layer formation in 2010 and 2011. Overall, firn temperatures during the years 2009-13 increased by 0.6°C.

Original languageEnglish
Number of pages10
JournalAnnals of Glaciology
Volume57
Issue number72
DOIs
Publication statusPublished - 1 Jul 2016

Keywords

  • accumulation area
  • firn
  • Greenland ice sheet
  • percolation
  • refreezing
  • superimposed ice

Programme Area

  • Programme Area 5: Nature and Climate

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