Estimates of the refreezing rate in an ice-shelf borehole

Title Estimates of the refreezing rate in an ice-shelf borehole
Publication Type
Journal Article
Year
2013
Author(s) Kenneth Hughes , Pat Langhorne, Michael Williams
Journal/ Publication
Journal of Glaciology
Volume
59
Issue
217
Pagination
938-948
Abstract

The refreezing rate of a borehole drilled through a 252 m thick region of the Ross Ice Shelf, Antarctica, is determined using oceanographic measurements over two periods of a day. We first use a method based on the conservation of salt in the supercooled salt water of the borehole. This is compared to a model using a numerical solution of the heat equation to find the temperature distribution in the host ice, allowing ice growth to be calculated from the balance of heat fluxes at the ice/water interface. This second method broadly confirms the refreezing rates deduced from salinity measurements, giving confidence in the generalization of this simple heat-flux model to predict refreezing rates of other boreholes. Predictions from both are subject to uncertainty due to the poorly defined value of the solid fraction of ice that freezes in a supercooled volume of sea water. This is taken to be 0.5 ± 0.1 throughout this study. The predicted rates are also strongly dependent on the initial and boundary conditions chosen, but results show the initial diameter of 600 mm decreases at a rate of ∼3–5 mm h−1 in an ice shelf with a minimum temperature of −22°C.

DOI
10.3189/2013JoG12J117
URL
Categories Borehole Closure, Hot Water Drilling
Citation Kenneth Hughes , Pat Langhorne, Michael Williams ( 2013 ) Estimates of the refreezing rate in an ice-shelf borehole. Journal of Glaciology , 59 , 217 , 938-948 . doi: 10.3189/2013JoG12J117
Lead Author
Kenneth Hughes