Indication of high basal melting at EastGRIP drill site on the Northeast Greenland Ice Stream

• Main Authors: Zeising, Ole, Humbert, Angelika
• Format: Text
• Language: English
• Published: 2021
• Subjects: Greenland; glacier; Ice Sheet
• Online Access: https://doi.org/10.5194/tc-2021-37; https://tc.copernicus.org/preprints/tc-2021-37/

The accelerated ice flow of ice streams that reach far into the interior of the ice sheet, is associate with lubrication of the ice sheet base by basal melt water. However, the amount of basal melting under the large ice streams – such as the Northeast Greenland Ice Stream (NEGIS) – are largely unknown. In-situ measurements of basal melt rates are important from various perspectives as they indicate the heat budget, the hydrological regime and the role of sliding in glacier motion. The few previous estimates of basal melt rates in the NEGIS region were 0.1 m a −1 and more, based on radiostratigraphy methods. These finding raised the question of the heat source, since even an increased geothermal heat flux could not deliver the necessary amount of heat. Here, we present basal melt rates at the recent deep drill site EastGRIP, located in the center of NEGIS. Within two subsequent years, we found basal melt rates of (0.16–0.22) ± 0.01 m a −1 , that are based on analysis of repeated phase-sensitive radar measurements. In order to quantify the contribution of processes that cause a heat flux into the ice, we carried out an assessment of the energy sources and found the subglacial water system to play a key role in facilitating such high melt rates.