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Limited Impact of Subglacial Supercooling Freeze‐on for Greenland Ice Sheet Stratigraphy
Author(s) -
Dow Christine F.,
Karlsson Nanna B.,
Werder Mauro A.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl076251
Subject(s) - geology , supercooling , ice sheet , greenland ice sheet , ice stream , cryosphere , freezing point , depth sounding , ice formation , geomorphology , climatology , geophysics , atmospheric sciences , oceanography , sea ice , meteorology , geography , physics , thermodynamics
Large units of disrupted radiostratigraphy (UDR) are visible in many radio‐echo sounding data sets from the Greenland Ice Sheet. This study investigates whether supercooling freeze‐on rates at the bed can cause the observed UDR. We use a subglacial hydrology model to calculate both freezing and melting rates at the base of the ice sheet in a distributed sheet and within basal channels. We find that while supercooling freeze‐on is a phenomenon that occurs in many areas of the ice sheet, there is no discernible correlation with the occurrence of UDR. The supercooling freeze‐on rates are so low that it would require tens of thousands of years with minimal downstream ice motion to form the hundreds of meters of disrupted radiostratigraphy. Overall, the melt rates at the base of the ice sheet greatly overwhelm the freeze‐on rates, which has implications for mass balance calculations of Greenland ice.