Mr Wilfred Theakstone - Research
The Svartisen Research Project is concerned primarily with the area’s glaciers. Initially, studies were concentrated on the largest glacier, Austerdalsisen: investigations beneath the glacier and at its upper surface were carried out through a period of several years. Twentieth-century changes of Austerdalsisen have been dominated by calving into marginal lakes. In the 1960s, I established photographic stations in front of many of the Svartisen glaciers and I have monitored their subsequent variations. These have been influenced by climatic changes since the late 19th century. Together with colleagues from Aarhus University, I carried out terrestrial photogrammetric surveys of the largest outlet glaciers of the East Svartisen ice cap in the 1970s and 1980s. Annual outbursts of the lake dammed at the western margin of Austerdalsisen were ended by the completion of a flood relief tunnel in 1959. Permanent lowering of the lake surface level resulted in the exposure of lacustrine sediments, which subsequently were eroded and reworked by terrestrial and fluvial processes. Older glacial sediments north of the East Svartisen ice cap contain calcareous concretions.
The programme of the Okstindan Glacier Project, undertaken jointly with personnel from Aarhus University, has included observations of the area’s two easternmost glaciers, but the principal focus has been the largest glacier, Austre Okstindbreen. Mass balance studies between 1985 and 1995, observations of surface flow and strain and mapping using Global Positioning System surveys were undertaken alongside oxygen isotope analyses of the snow which accumulated on the glacier in winter and of the river water issuing from the glacier in summer. Oxygen isotope analysis of daily precipitation at Tustervatn, 25 km south-west of Austre Okstindbreen, through a 7-year period, 1997-2004, revealed a strong seasonal pattern that reflected the influence of regional temperatures, air mass trajectories and the North Atlantic Oscillation.
Since 2000, I have taken part in a programme of glaciological studies in south-west China with Dr He Yuanqing and his colleagues at the Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences at Lanzhou. Changes of the monsoonal temperate glaciers during recent decades have been influenced byrising temperatures. Most of the annual precipitation in the Mount Yulong area, Yunnan Province, falls during the summer monsoon. The chemistry of winter precipitation differs from that of the summer, as dust is brought to the glacier from continental areas.