GBaTSv2: a revised synthesis of the likely basal thermal state of the Greenland Ice Sheet
<p>The basal thermal state (frozen or thawed) of the Greenland Ice Sheet is under-constrained due to few direct measurements, yet knowledge of this state is becoming increasingly important to interpret modern changes in ice flow. The first synthesis of this state relied on inferences from wide...
Main Authors: | , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2022-08-01
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Series: | The Cryosphere |
Online Access: | https://tc.copernicus.org/articles/16/3033/2022/tc-16-3033-2022.pdf |
Summary: | <p>The basal thermal state (frozen or thawed) of the Greenland Ice
Sheet is under-constrained due to few direct measurements, yet knowledge of
this state is becoming increasingly important to interpret modern changes in
ice flow. The first synthesis of this state relied on inferences from
widespread airborne and satellite observations and numerical models, for
which most of the underlying datasets have since been updated. Further, new
and independent constraints on the basal thermal state have been developed
from analysis of basal and englacial reflections observed by airborne radar
sounding. Here we synthesize constraints on the Greenland Ice Sheet's basal
thermal state from boreholes, thermomechanical ice-flow models that
participated in the Ice Sheet Model Intercomparison Project for CMIP6
(ISMIP6; Coupled Model Intercomparison Project Phase 6), IceBridge BedMachine Greenland v4 bed topography, Making Earth Science Data Records
for Use in Research Environments (MEaSUREs) Multi-Year Greenland Ice Sheet Velocity
Mosaic v1 and multiple inferences of a thawed bed from airborne radar
sounding. Most constraints can only identify where the bed is likely thawed
rather than where it is frozen. This revised synthesis of the Greenland
likely Basal Thermal State version 2 (GBaTSv2) indicates that 33 % of the
ice sheet's bed is likely thawed, 40 % is likely frozen and the remainder
(28 %) is too uncertain to specify. The spatial pattern of GBaTSv2 is
broadly similar to the previous synthesis, including a scalloped frozen core
and thawed outlet-glacier systems. Although the likely basal thermal state
of nearly half (46 %) of the ice sheet changed designation, the assigned
state changed from likely frozen to likely thawed (or vice versa) for less
than 6 % of the ice sheet. This revised synthesis suggests that more of
northern Greenland is likely thawed at its bed and conversely that more of
southern Greenland is likely frozen, both of which influence interpretation
of the ice sheet's present subglacial hydrology and models of its future
evolution. The GBaTSv2 dataset, including both code that performed the
analysis and the resulting datasets, is freely available at
<a href="https://doi.org/10.5281/zenodo.6759384">https://doi.org/10.5281/zenodo.6759384</a> (MacGregor, 2022).</p> |
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ISSN: | 1994-0416 1994-0424 |