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

Charalampidis, Charalampos,1983-Uppsala universitet,Luft-, vatten- och landskapslära,Geol Survey Denmark & Greenland GEUS, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark,Ice, Climate and Environment (author)

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 c. 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 degrees C and 1.7 degrees 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 degrees 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 degrees C.

van As, DirkGeol Survey Denmark & Greenland GEUS, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark (author)
Colgan, William T.Geol Survey Denmark & Greenland GEUS, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark.; York Univ, Dept Earth & Space Sci & Engn, 4700 Keele St, Toronto, ON M3J 1P3, Canada (author)
Fausto, Robert S.Geol Survey Denmark & Greenland GEUS, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark (author)
MacFerrin, MichaelUniv Colorado, CIRES, 216 UCB, Boulder, CO 80309 USA (author)
Machguth, HorstGeol Survey Denmark & Greenland GEUS, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark.; Tech Univ Denmark, Arctic Technol Ctr ARTEK, Byg 118, DK-2800 Lyngby, Denmark (author)
Uppsala universitetLuft-, vatten- och landskapslära (creator_code:org_t)

In:Annals of Glaciology: International Glaciological Society57:72, s. 1-100260-30551727-5644

By the author/editor: Charalampidis, C ...; van As, Dirk; Colgan, William ...; Fausto, Robert S ...; MacFerrin, Micha ...; Machguth, Horst

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Earth and Relate ...; and Climate Research

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