In:
The Cryosphere, Copernicus GmbH, Vol. 16, No. 10 ( 2022-10-26), p. 4513-4535
Abstract:
Abstract. The thermal regime of glaciers and ice caps represents
the internal distribution of ice temperatures. An accurate knowledge of the
thermal regime of glaciers and ice caps is important to understand their
dynamics and response to climate change and to model their evolution.
Although the assumption is that most ice masses in the Tien Shan are
polythermal, this has not been examined in appropriate detail so far. In
this research, we investigate the thermal regime of the Grigoriev ice cap
and the Sary-Tor glacier, both located in the inner Tien Shan in Kyrgyzstan,
using a 3D higher-order thermomechanical ice flow model. Input data and
boundary conditions are inferred from a surface energy mass balance model, a
historical air temperature and precipitation series, ice thickness
measurements and reconstructions, and digital elevation models. Calibration
and validation of the englacial temperatures are performed using historical
borehole measurements on the Grigoriev ice cap and radar measurements for
the Sary-Tor glacier. The results of this study reveal a polythermal
structure of the Sary-Tor glacier and a cold structure of the Grigoriev ice
cap. The difference is related to the larger amount of snow (insulation) and
refreezing meltwater (release of latent heat) for the Sary-Tor glacier,
resulting in higher surface layer temperature, especially in the
accumulation area, which is subsequently advected downstream. Further, ice
velocities are much lower for the Grigoriev ice cap, with consequent lower
horizontal advection rates. A detailed analysis concerning the influence of
temperature and precipitation changes at the surface reveals that the
thermal structure of both ice bodies is not constant over time, with recent
climate change causing increasing ice temperatures in higher areas. The
selected ice masses are representative examples of the (inner) Tien Shan
glaciers and ice caps. Therefore, our findings and the calibrated parameters
can be generalised, allowing improved understanding of the dynamics and
future evolution of other glaciers and ice caps in the region.
Type of Medium:
Online Resource
ISSN:
1994-0424
DOI:
10.5194/tc-16-4513-2022
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2393169-3
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