Seasonal effects on ice-wedge thermal variation in East Antarctica: a time series approach

• Main Authors: RAFFI, Rossana, BRAMATI, Maria Caterina, M. Baldassarre, M. Guglielmin
• Other Authors: Royal Society Expert Panel on Antarctic Sciences, Raffi, Rossana, Bramati, Maria Caterina, M., Baldassarre, M., Guglielmin
• Format: Conference Object
• Language: English
• Published: 2014 SCAR Open Science Conference - XXXIII SCAR 2014
• Subjects: Ice wedge; Antarctica; thermal regime; Baker Rocks; Boomerang Glacier; East Antarctica; Jackman; Mount Jackman; Victoria Land; Antarc*
• Online Access: http://hdl.handle.net/11573/656630; http://www.scar2014.com/assets/SCAR_and_COMNAP_2014_Abstract_Document.pdf

This research aims at studying the thermal variation of ice wedges at various depths. In particular, the analysis of ice-wedge top and bottom, ground surface and air temperatures are undertaken. The active layer depth is calculated through seasons and years using hourly data at three sites in northern Victoria Land: Baker Rocks, Boomerang Glacier and Mount Jackman. The recording period is from 2004 to 2013 at Baker Rocks and Boomerang Glacier, and from 2006 to 2013 at Mount Jackman. Daily mean ground surface temperatures (DMGST) and daily mean air temperatures are highly correlated at Baker Rocks (r2=0.96), Boomerang Glacier (r2 =0.95), and Mount Jackman (r2=0.92) sites. This shows that the ground surface temperature at measurement sites responds strongly to air temperature. Moreover, hourly ground surface temperature and DMGST are generally lower than the air temperature in the winter season, which shows the absence of a significant snow cover. Standard deviations of the hourly temperature show that high temperature variability can exist over one month, with higher variability in winter than in summer. Frequent and large temperature fluctuations are common throughout winter with either a sharp drop or a rapid increase both in air and ground surface temperature. Variations of 25°C to 30°C were recorded over periods of one to four days. The overall variability of temperatures is decomposed using spectral analysis in order to isolate seasonal effects from cycles and long term trends. Moreover, spectral analysis is also applied to the long term temperature data (26 years) from six automatic weather stations, located in northern Victoria Land, to compare the temperature series recorded over different time spans and to identify possible fitting trends. The time series approach in the frequency domain is quite new in this field and it represents therefore the main contribution to the existing literature.