Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet
2016 (English)In: Annals of Glaciology, ISSN 0260-3055, E-ISSN 1727-5644, Vol. 57, no 72, S0260305516000021Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
Cambridge University Press, 2016. Vol. 57, no 72, S0260305516000021
Greenland ice sheet, accumulation area, firn, percolation, refreezing, superimposed ice
IdentifiersURN: urn:nbn:se:uu:diva-284357DOI: 10.1017/aog.2016.2OAI: oai:DiVA.org:uu-284357DiVA: diva2:920213
ProjectsStability and Variations of Arctic Land Ice (SVALI)Programme for Monitiring of the Greenland Ice Sheet (PROMICE)Greenland Analogue Project (GAP)