Distribution of cold and temperate ice in glaciers on the Nordenskiold Land, Spitsbergen, from ground-based radio-echo sounding

• Published in: Ice and Snow
• Main Authors: Yu. Macheret Ya., A. Glazovsky F., I. Lavrentiev I., I. Marchuk O., Ю. Мачерет Я., А. Глазовский Ф., И. Лаврентьев И., И. Марчук О.
• Other Authors: This work was supported by the Statе contract № 0148-2019-0004 (АААА-А19119022190172-5). Cartographic work was carried out under the grant RFBR № 18-05-60067, Статья подготовлена по теме Государственного задания № 0148-2019-0004 (АААА-А19-119022190172-5). Картографические работы проводились в рамках гранта РФФИ № 18-05-60067
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: IGRAS 2019
• Subjects: cold and temperate ice; glaciers; ground-based radio-echo sounding; Svalbard; ледники; наземное радиозондирование; холодный и тёплый лёд; Шпицберген; Annals of Glaciology; Antarctic and Alpine Research; Arctic; glacier; Polar Research; Polar Science; The Cryosphere; Spitsbergen
• Online Access: https://ice-snow.igras.ru/jour/article/view/557; https://doi.org/10.15356/20766734-2019-2-430

Data of ground-based radio-echo sounding of 16 glaciers located on the Nordenskiold Land, Spitsbergen, carried out in springs of 1999, 2007 and 2010–2013, allowed defining five glaciers as of the cold thermal type while other eleven ones were polythermal glaciers. In the last ones (polythermal) the average thickness of the upper layer of cold ice and the bottom layer of temperate ice was equal to 11-66 m and 15-96 m, respectively. The ratio of these thicknesses varies from 0.32 to 2.28, and the volume fraction of temperate ice in the total volume of the glaciers varies from 1 to 74% and changes from 0 to 50% in the ablation zone up to 80% in the accumulation zone. Thickness of cold ice was determined by measured delay time of radar reflections from cold-temperate surface (CTS) while thickness of temperate ice was derived as a difference between the total thickness of the glacier and the thickness of its cold ice. For interpretation of radar reflections from CTS we used the noticeable distinction in character of the radar reflections from the upper and lower thicknesses of glacier: absence of internal reflections (excluding reflections from buried crevasses and glacier wells) from upper cold ice layer and a great number of reflections of hyperbolic form from the lower layer related to strong scattering of radio waves by water inclusions in the temperate ice. According to the measurements, relative power of the radar reflections from CTS is by 5,5–14,2 dB smaller than those from the bedrock, that can be considered as an indicator of smaller water content at CTS; so, the repeated measurements of their relative power can be used for estimation of temporal changes in the water content at these boundaries. In layers of the temperate ice, the series of vertical hyperbolic reflections penetrating the cold ice down to CTS and further to the bedrock were detected. Such reflections are related to buried crevasses and/or the glacier wells and can serve as sources of the water permeating during the melt periods from the ...