Geomatic methods applied to the study of the front position changes of Johnsons and Hurd Glaciers, Livingston Island, Antarctica, between 1957 and 2013

Abstract

Abstract. Various geomatic measurement techniques can be efficiently combined for surveying glacier fronts. Aerial photographs and satellite images can be used to determine the position of the glacier terminus. If the glacier front is easily accessible, the classic surveys using theodolite or total station, GNSS (Global Navigation Satellite System) techniques, laser-scanner or close-range photogrammetry are possible. When the accessibility to the glacier front is difficult or impossible, close-range photogrammetry proves to be useful, inexpensive and fast. In this paper, a methodology combining photogrammetric methods and other techniques is applied to determine the calving front position of Johnsons Glacier. Images taken in 2013 with an inexpensive nonmetric digital camera are georeferenced to a global coordinate system by measuring, using GNSS techniques, support points in accessible areas close to the glacier front, from which control points in inaccessible points on the glacier surface near its calving front are determined with theodolite using the direct intersection method. The front position changes of Johnsons Glacier during the period 1957-2013, as well as those of the land-terminating fronts of Argentina, Las Palmas and Sally Rocks lobes of Hurd glacier, are determined from different geomatic techniques such as surface-based GNSS measurements, aerial photogrammetry and satellite optical imagery. This provides a set of frontal positions useful, e.g., for glacier dynamics modeling and mass balance studies.

Geomicrobiological Heterogeneity of Lithic Habitats in the Extreme Environment of Antarctic Nunataks: A Potential Early Mars Analog

“…We thus concluded that carbon fixation in the three substrate ecosystems occurred dominantly through the Calvin-Benson-Bassham cycle, whereas other autotrophic pathways (e.g., reductive acetyl-CoA resulting into δ 13 C values from −28 to −44‰; (Preuß et al, 1989) were most likely minority. The range of δ 15 N observed in the soils (from −4 to −7 ‰) suggested fractionations related to N 2 fixation via nitrogenase (Robinson, 2001), consistent with the widespread presence of nitrogen fixing proteins detected by the LDChip. Therefore, we are able to suggest photosynthetic and diazotrophic microorganisms may play a pivotal role in the ecosystem as primary producers, thus permitting an active microbial cycling at these nunataks.…”

“…Hurd Peninsula, located in the southern half of Livingston Island, comprises about 27 km 2 , from South Bay in the northwest to False Bay in the southeast (Figure 1A). The interior of the peninsula is mainly covered by the temperate ice cap of Johnsons' tidewater glacier, flowing northwestwards, and Hurd Glacier, which presents various land-terminating tongues flowing southwestwards (Molina et al, 2007;Rodríguez Cielos et al, 2016). Two main lithological sequences in the exposed areas of the peninsula emerge from the ice cap as nunataks and surround the milder terrestrial ends of Hurd Glacier (Garrido-Benavent et al, 2020).…”

Differential Colonization and Succession of Microbial Communities in Rock and Soil Substrates on a Maritime Antarctic Glacier Forefield

“…13 and 23 years since ice retreat. The glacier retreat dates are known because they correspond to measurements of glacier front positions determined in situ by the authors using Global Navigation Satellite System (<1 and 13 years) or from aerial photographs (23 years), both made during periods when the snow cover had melted away (Rodríguez-Cielos et al, 2016;Machío et al, 2017). These sites ranged from bare soils close to the glacier terminus to 23-years ice-free areas dominated by mosses ( Figure 1B).…”

Remote Sensing of Antarctic Glacier and Ice-Shelf Front Dynamics—A Review

“…For example, many studies are designed to only assess the overall change between two time steps to calculate the average retreat or advance rate in order to identify long-term trends [27]. Many studies also assess front fluctuations based on more or less decadal intervals [23,33] or even on an annual basis [133]. The length of an interval is strongly connected to scene availability [24,40,81].…”