Antifreeze thermal ice core drilling: an effective approach to the acquisition of ice cores

Antifreeze thermal electric drills have a long history of ice drilling in t emperate, subpolar and polar glaciers. Shallow, intermediate and deep ice c ores have been obtained in Arctic, Antarctic and on high elevation glaciers . Many merits and drawbacks of antifreeze thermal technology have been disc overed over the past 25 years. A modified version of the antifreeze thermal electric ice coring drill has recently been developed and tested in the la boratory and in the field for use with an ethanol-water solution. This ther mal drill reduces thermal stresses in an ice core by a factor of 5 compared to that of conventional thermal drills and produces good quality ice core. The new drill was used to obtain a 315-m ice core in Franz Josef Land in t he high Russian Arctic. It is viewed as a practical and cost-effective alte rnative to the electromechanical fluid-operated drills for intermediate dep th ice coring in subpolar sand remote high elevation glaciers. Alternating an electromechanical drill with the antifreeze thermal drill in the bottom of Antarctic Ice Sheet may provide a cost effective way for acquiring good quality multiple ice cores. This approach would also reduce possible enviro nmental impact on subglacial lakes and allow making multiple access holes. Previous results of ice coring with an ethanol-water solution are summarize d below. Then, the new thermal drilling equipment along with the results of laboratory and field tests are presented. All aspects of the antifreeze th ermal electric drilling process are discussed along with prospects for furt her improvements. (C) 1998 Elsevier Science B.V. All rights reserved.