Processes influencing heat transfer in the near-surface ice of Greenland's ablation zone

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...

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Vydané v:The cryosphere Ročník 12; číslo 10; s. 3215 - 3227
Hlavní autori: Hills, Benjamin H., Harper, Joel T., Meierbachtol, Toby W., Johnson, Jesse V., Humphrey, Neil F., Wright, Patrick J.
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: Katlenburg-Lindau Copernicus GmbH 08.10.2018
Copernicus Publications
Predmet:
Ablation
Air temperature
Analysis
Annual temperatures
Environmental aspects
Heat transfer
Heating
Ice
Ice temperatures
In situ measurement
Insulating materials
Mathematical models
Meltwater
Modelling
Near-surface layer
Strings
Surface boundary layer
Surface layers
Surface-ice melting
Temperature
Temperature effects
Temperature gradients
Temperature variability
Thermal analysis
Thermal insulation
Thermal models
Thermal structure
Transient heating
Greenland
ISSN:1994-0424, 1994-0416, 1994-0424, 1994-0416
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Popis
Shrnutí: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.
Bibliografia:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 14
ISSN:1994-0424
1994-0416
1994-0424
1994-0416
DOI:10.5194/tc-12-3215-2018