Ice-wedge temperature trends in East Antarctica: a thermal puzzle?

• Main Authors: Raffi R., Bramati M. C., Baldassarre M. A.
• Other Authors: Raffi, R., Bramati, M. C., Baldassarre, M. A.
• Format: Conference Object
• Language: English
• Published: place:Goa, India 2015
• Subjects: ice wedge; temperature; time serie; Antarctica; Antarc*; East Antarctica; Victoria Land
• Online Access: http://hdl.handle.net/11573/1427372

A monitoring programme on ice-wedge thermal regime has been undertaken from 2004 to 2014 at three sites in northern Victoria Land: Baker Rocks (74°12’27” S; 164°50’01” E; 11 m a.s.l.), Boomerang Glacier (74°30’13” S; 163°50’09” E; 874 m a.s.l.) and Mount Jackman (72°23’07” S; 163°10’49” E; 1326 m a.s.l.). Four sensors took hourly temperature of the air, the ground surface, the ice-wedge top and bottom. In the recording period the mean monthly ground surface temperature (recorded at 2 cm) (GST) ranged between -37.7°C (July 2004) and 9°C (January 2015) at Baker Rocks, -34.4°C (July 2004) and -8.9°C (January 2015) at Boomerang Glacier and -38°C (July 2010) and -0.7°C (December 2012) at Mount Jackman respectively. In the same period the mean monthly air temperature ranged between -34.4°C (July 2004) and 1.3°C (January 2007) at Baker Rocks, -33.5°C (July 2004) and -3.1°C (January 2013) at Boomerang Glacier and -34.7 (July 2010)°C and -7.7°C (January 2014) at Mount Jackman, respectively. Air temperature is always higher than GST in winter, indicating the absence of a significant snow cover. On the other hand, during summer the air temperature is lower than the GST. As for the mean monthly temperature of the ice-wedge top (recorded at -50 cm) ranges between -27.6°C and 0°C at Baker Rocks, between -29.9°C and -4.1°C at Boomerang Glacier and between -36.1°C and -1.5°C at Mount Jackman, respectively. At the ice-wedge bottom (at -80cm), the monthly average temperature is between -26.4°C and -2.6°C at Baker Rocks, between -30°C and -4.6°C at Boomerang Glacier and between -35.1°C and -3.2°C at Mount Jackman, respectively. The thermal offset measured at the top of ice wedges is small, ranging between -2.0 °C and -0.5 °C at Baker Rocks, -0.5 °C and -0.1 °C at Boomerang Glacier and -0.6 °C and -0.1 °C at Mount Jackman, respectively. The active layer has been computed daily for each of the three sites, according to Gold and Lachenbruch (1973). The monthly average thickness of the active layer ranges between 0.17 m and 0.61 m at ...