Speaker
Dr
Martin Luethi
(University of Zurich, Geography)
Description
Glacier ice at the melting temperature may contain up to 6% of unfrozen water,
as was inferred with indirect methods such as ice-penetrating radar. This
inter-grain water influences ice deformation, the thermal structure of ice
sheets, and subglacial hydrology.
We determined by the content of free water in-situ in ice caves and at the
base of serveral temperate glaciers. The calorimeter consists of an active
cooling system in a central borehole and a set of thermistors which are placed
in several distances from the center. We thus measure the velocity of the
freezing front as well as the cooling rates. With help of a 3D finite element
heat flow model synthetic freezing curves are obtained for various initial
water contents. Matching these synthetic curves to the measurements yields
in-situ water contents between 0 and about 3% in basal ice. These values
confirm the indirectly derived free water contents within the ice matrix of Alpine glaciers.
Significance statement
We present unique in-situ measurements of free water within the ice matrix of Alpine glaciers.
Primary author
Dr
Martin Luethi
(University of Zurich, Geography)
