Synoptic circulation patterns and its relationship with ground thermal characteristics along an altitudinal transect on sub-Antarctic Marion Island

• Main Author: Bierman, Stefni
• Format: Master Thesis
• Language: English
• Published: University of Fort Hare 2014
• Subjects: Antarc*; Antarctic; Marion Island
• Online Access: http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:11516; http://hdl.handle.net/10353/d1015532

The climate of Marion Island is driven by synoptic weather patterns which have also been suggested to influence the soil thermal characteristics. The primary aim of this work was to examine the effect of synoptic weather systems on soil temperature dynamics on an altitudinal gradient on the eastern side of Marion Island. The study specifically addresses the implications of climate change on future soil thermal dynamics in a maritime sub-Antarctic environment. Ground temperature were obtained from three ground temperature monitoring stations on the eastern side of Marion Island, which were established along an altitudinal gradient at Long Ridge North (200m a.s.l.), Katedraalkrans (750m a.s.l) and at Delta Extension (1000m a.s.l.). To assess the synoptic weather circulation patterns, a synoptic climate classification methodology that is based on the single station principal component (PCA) and cluster analysis were used. Results show that certain clusters were more dominant than others and over the measured time span certain synoptic weather patterns, mainly cyclonic air circulation types, have decreased while anticyclonic circulation have increased. Soil frost occurs at all three stations on Marion Island, not only under cyclonic circulations (as previously suggested) but significantly under anticyclonic air mass circulation as well. Soil frost is dependent on the duration of post-cyclonic Antarctic air mass circulation. Synoptic weather patterns are also affecting ground surface lapse rates. Changes from positive to negative lapse rates were observed and this predominantly occurred under the atmospheric circulation pattern associated with clusters that are predominantly anticyclonic. Long term climatic change as predicted by the PCA show a reduction in low pressure systems or more anticyclonic conditions affecting the island. These change will significantly affect the soil thermal dynamics at an altitudinal scale on sub-Antarctic Marion Island.