A monitoring programme on ice-wedge thermal regime has been undertaken from 2004 to 2016 at three sites in Northern Victoria Land. The selected sites, Baker Rocks (BR) (74°12’27” S; 164°50’01” E; 11 m a.s.l.), Boomerang Glacier (BG) (74°30’13” S; 163°50’09” E; 874 m a.s.l.) and Mount Jackman (MJ) (72°23’07” S; 163°10’49” E; 1326 m a.s.l.), are characterised by differing topographic, climatic and morphologic conditions (Raffi and Stenni, 2011). Active layer depth (ALT) was computed through linear interpolation between the maximum daily temperature at 2 cm and ice-wedge top depth; this depth was approximately assumed coincident with the maximum depth of the permafrost table during the observation period. ALT showed low annual variability, ranging between 46 cm and 50 cm, 21 cm and 30 cm, and 25 cm and 36 cm at BR, BG and MJ, respectively. The shallow active layer at BG was not within the range expected for sites situated along the coast of Northern Victoria Land (Cannone et al.,1998). The BG site is subject to the persistent occurrence of strong katabatic winds channelled by the nearby Priestley Glacier, thus inducing sublimation phenomena. ALT showed a slight increase trend at the three sites (+0.16 cm, +0.22 cm and +0.12 per year at BR, BG and MJ, respectively), and a good correlations with the summer daily mean ground surface temperature (GST) at BR and BG (ALT=2.87x+25.5, R2=0.7, and ALT=1.21x+11.85, R2=0.6) , as also highlighted by Guglielmin and Cannone (2012). On the other hand, ALT showed good correlations with the summer daily mean top temperature at MJ (ALT=2.92x+29.9, R2=0.6). Although the air temperature was almost stable, GST showed a slight warming trend during the summer at the three sites, but only statistically significant at BR (0.2 °C per year). The increase trend of summer GST at BR was enhanced by the increase trend of the summer thawing degree days (TDD at 2 cm; +13.36 °C per year; R2=0.6). References 1 Raffi, R. and Stenni B. 2011. Isotopic Composition and Thermal Regime of Ice wedges in Northern Victoria Land, East Antarctica. Permafrost and Periglacial Processes, 22, 65-83. 2 Cannone, N., Wagner, D., Hubberten, H.W. and Guglielmin, M. 2008. Biotic and abiotic factors influencing soil properties across a latitudinal gradient in Victoria Land, Antarctica. Geoderma, 144, 50-65. 3 Guglielmin, M. and Cannone N. 2012. A permafrost warming in a cooling Antarctica? Climatic Change, 111, 177-195.
Thermal regime and active layer thickness at three ice-wedge polygon sites in Northern Victoria Land, East Antarctica: results from 2004-2016 / Raffi, R.; Bramati, M. C.; Baldassarre, M. A.. - (2017), pp. 36-36. (Intervento presentato al convegno 1st International Workshop on Antarctic permafrost, periglacial processes and soils (ANTPAS) - From an expert group to a research program tenutosi a Varese; Italy).
Thermal regime and active layer thickness at three ice-wedge polygon sites in Northern Victoria Land, East Antarctica: results from 2004-2016
Raffi R.
;Bramati M. C.;Baldassarre M. A.
2017
Abstract
A monitoring programme on ice-wedge thermal regime has been undertaken from 2004 to 2016 at three sites in Northern Victoria Land. The selected sites, Baker Rocks (BR) (74°12’27” S; 164°50’01” E; 11 m a.s.l.), Boomerang Glacier (BG) (74°30’13” S; 163°50’09” E; 874 m a.s.l.) and Mount Jackman (MJ) (72°23’07” S; 163°10’49” E; 1326 m a.s.l.), are characterised by differing topographic, climatic and morphologic conditions (Raffi and Stenni, 2011). Active layer depth (ALT) was computed through linear interpolation between the maximum daily temperature at 2 cm and ice-wedge top depth; this depth was approximately assumed coincident with the maximum depth of the permafrost table during the observation period. ALT showed low annual variability, ranging between 46 cm and 50 cm, 21 cm and 30 cm, and 25 cm and 36 cm at BR, BG and MJ, respectively. The shallow active layer at BG was not within the range expected for sites situated along the coast of Northern Victoria Land (Cannone et al.,1998). The BG site is subject to the persistent occurrence of strong katabatic winds channelled by the nearby Priestley Glacier, thus inducing sublimation phenomena. ALT showed a slight increase trend at the three sites (+0.16 cm, +0.22 cm and +0.12 per year at BR, BG and MJ, respectively), and a good correlations with the summer daily mean ground surface temperature (GST) at BR and BG (ALT=2.87x+25.5, R2=0.7, and ALT=1.21x+11.85, R2=0.6) , as also highlighted by Guglielmin and Cannone (2012). On the other hand, ALT showed good correlations with the summer daily mean top temperature at MJ (ALT=2.92x+29.9, R2=0.6). Although the air temperature was almost stable, GST showed a slight warming trend during the summer at the three sites, but only statistically significant at BR (0.2 °C per year). The increase trend of summer GST at BR was enhanced by the increase trend of the summer thawing degree days (TDD at 2 cm; +13.36 °C per year; R2=0.6). References 1 Raffi, R. and Stenni B. 2011. Isotopic Composition and Thermal Regime of Ice wedges in Northern Victoria Land, East Antarctica. Permafrost and Periglacial Processes, 22, 65-83. 2 Cannone, N., Wagner, D., Hubberten, H.W. and Guglielmin, M. 2008. Biotic and abiotic factors influencing soil properties across a latitudinal gradient in Victoria Land, Antarctica. Geoderma, 144, 50-65. 3 Guglielmin, M. and Cannone N. 2012. A permafrost warming in a cooling Antarctica? Climatic Change, 111, 177-195.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
