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.Link to the data repository: https://doi.pangaea.de/10.1594/PANGAEA.845379.
Highlights
Hurd and Johnsons glaciers are located in Hurd Peninsula, Livingston Island, the second largest island of the South Shetland Islands (SSI) archipelago (Fig. 1)
The current study aims to make available to the scientific community the whole set of front positions of Johnsons Glacier, and Argentina, las Palmas and Sally Rocks fronts of Hurd Glacier, between 1957 and 2013
The first subject is relevant, since the glaciers in the Antarctic Peninsula region are an exception among the WGMS-monitored glaciers, in the sense that they have experienced sustained positive surface mass balances starting around 2007–2008
Summary
Hurd and Johnsons glaciers are located in Hurd Peninsula, Livingston Island, the second largest island of the South Shetland Islands (SSI) archipelago (Fig. 1). Glaciological studies covering the whole Livingston Island include the analysis of Livingston ice cap front position changes 1956–1996 (Calvet et al, 1999), ground-penetrating radar surveys (Macheret et al, 2009) and estimates of ice discharge to the ocean (Osmanoglu et al, 2014). Their study only dealt with cartography of ash layers which originated from the eruptions in the neighboring Deception Island (see inset of Fig. 1) They did not determine Johnsons calving front position, since, due to the location of the observation points on the top of Johnsons/Charrúa Peak Molina et al (2007) analyzed the volume changes 1957– 2000 of Hurd Peninsula glaciers comparing digital elevation models (DEMs) for 1957, obtained by photogrammetric restitution from the British Antarctic Survey (BAS) aerial photographs of 1957 and theodolite and GNSS surface-based measurements in 1999–2001. The exclusion of the unnamed glacier basins U1, U2, U3 (Fig. 1) from our study is not relevant, since Hurd and Johnsons glaciers are the only Hurd Peninsula glacier basins included in the WGMS database
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