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 temperate, subpolar and polar glaciers. Shallow, intermediate and deep ice cores have been obtained in Arctic, Antarctic and on high elevation glaciers. Many merits and drawbacks of antifreeze thermal technology have been discovered over the past 25 years. A modified version of the antifreeze thermal electric ice coring drill has recently been developed and tested in the laboratory and in the field for use with an ethanol–water solution. This thermal 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 the high Russian Arctic. It is viewed as a practical and cost-effective alternative to the electromechanical fluid-operated drills for intermediate depth ice coring in subpolar and 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 environmental impact on subglacial lakes and allow making multiple access holes. Previous results of ice coring with an ethanol–water solution are summarized below. Then, the new thermal drilling equipment along with the results of laboratory and field tests are presented. All aspects of the antifreeze thermal electric drilling process are discussed along with prospects for further improvements. q 1998 Elsevier Science B.V. All rights reserved.