Short-term Glacial Calving Processes at Kronebreen-Kongsvegen, Svalbard
Tinder, Phaedra Calista
MetadataShow full item record
Calving is an important component of glacier mass loss, but it remains difficult to model and directly influences sedimentological processes at the ice margin. As part of the Svalbard REU, this study aims to characterize the short-term calving processes at a tidewater glacier and establish a baseline dataset to which future and contemporary studies can be compared. The study was conducted during two weeks in July and August of 2009 at the head of Kronebreen-Kongsvegen glacier system in Kongsfjorden, Svalbard. Two water pressure gauges deployed on the north and south sides of the fjord, adjacent to the glacier face, logged water levels at ten-second intervals. Air pressure and fjord salinity were used to convert water pressure to water depth. The higher frequency water level changes were analyzed to identify large calving events and study their frequency, size, and origin along the calving front. The timing and magnitude of calving events also were compared with potential external forcing mechanisms, such as weather, tidal stage, and local water depth. The pressure-logged wave records were calibrated and confirmed by comparison with observational data from visual logging of calving events at the site. The 15-day study period occurred during the height of the summer melt season. Over the entire record, the frequency of calving events appears to follow the changing tidal amplitude, with reduced calving after the neap tide interval. The observed relationship between calving frequency and tidal stage has been documented at Alaskan glaciers and other locations, and linked causatively by the explanation of increased circulation at the glacier front, as well as the destabilizing effect of buoyancy on the ice front. Fjord water depth at the glacier front influences the formation of “calving bays” where a majority of calving events were observed and the majority of ice loss occurred, as confirmed by satellite imagery. This project is part of a multi-year study of the response of Kronebreen-Kongsvegen to climate change, and also addresses the problem of constraining calving mechanisms and dynamics. Proper methodology in association with deployment of multiple water depth/pressure loggers placed close to a calving glacier terminus are recommended as an effective means of studying calving processes at a high resolution over various time intervals.