97 resultados para Event-Study
Resumo:
The study of glacier fronts combines different geomatics measurement techniques as the classic survey using total station or theodolite, technical GNSS (Global Navigation Satellite System), using laser-scanner or using photogrammetry (air or ground). The measure by direct methods (classical surveying and GNSS) is useful and fast when accessibility to the glaciers fronts is easy, while it is practically impossible to realize, in the case of glacier fronts that end up in the sea (tide water glaciers). In this paper, a methodology that combines photogrammetric methods and other techniques for lifting the front of the glacier Johnsons, inaccessible is studied. The images obtained from the front, come from a non-metric digital camera; its georeferencing to a global coordinate system is performed by measuring points GNSS support in accessible areas of the glacier front side and applying methods of direct intersection in inaccessible points of the front, taking measurements with theodolite. The result of observations obtained were applied to study the temporal evolution (1957-2014) of the position of the Johnsons glacier front and the position of the Argentina, Las Palmas and Sally Rocks lobes front (Hurd glacier).
Resumo:
Various physical properties of snow and sea ice were measured during ice stations in the Western Weddell Sea, Antarctic, during the POLARSTERN cruise ANT-XXIII/7 (WWOS) in 2006. Most stations were reached via a gangway directly from the vessels others by helicopter. All vertical positions are corrected to freeboard, e.g. z=0 represents the snow-ice interface. More detailed information about the data sets and methods are available from the cruise report (section 4 sea-ice physics).