In:
The Cryosphere, Copernicus GmbH, Vol. 12, No. 10 ( 2018-10-08), p. 3215-3227
Abstract:
Abstract. To assess the influence of various heat transfer processes on the
thermal structure of near-surface ice in Greenland's ablation zone, we
compare in situ measurements with thermal modeling experiments. A total of
seven temperature strings were installed at three different field sites,
each with between 17 and 32 sensors and extending up to 21 m below the
ice surface. In one string, temperatures were measured every 30 min, and
the record is continuous for more than 3 years. We use these measured
ice temperatures to constrain our modeling experiments, focusing on four
isolated processes and assessing the relative importance of each for the
near-surface ice temperature: (1) the moving boundary of an ablating surface,
(2) thermal insulation by snow, (3) radiative energy input, and (4) subsurface
ice temperature gradients below the seasonally active near-surface layer. In
addition to these four processes, transient heating events were observed in
two of the temperature strings. Despite no observations of meltwater
pathways to the subsurface, these heating events are likely the refreezing
of liquid water below 5–10 m of cold ice. Together with subsurface
refreezing, the five heat transfer mechanisms presented here account for
measured differences of up to 3 ∘C between the mean annual air
temperature and the ice temperature at the depth where annual temperature
variability is dissipated. Thus, in Greenland's ablation zone, the mean
annual air temperature is not a reliable predictor of the near-surface ice
temperature, as is commonly assumed.
Type of Medium:
Online Resource
ISSN:
1994-0424
DOI:
10.5194/tc-12-3215-2018
DOI:
10.5194/tc-12-3215-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2393169-3
