Characterising fjord circulation patterns and ice flux from time-lapse imagery at Sermilik Fjord, southeast Greenland

Abstract:

Evidence suggests that the synchronous acceleration and thinning in the early 2000s of Greenland’s southeast glaciers were triggered by increased submarine melting. This important control on the region’s mass balance is influenced by changes in the strength of coastal currents, which are also believed to be the cause of the subsequent slowdown of the mid-2000s. While warming of the subpolar North Atlantic and increased runoff are blamed for the enhanced submarine melting at the glacier margins, the physical processes that connect them remain largely unknown. Our lack of understanding of coastal currents and associated fluxes is due largely to a lack of observations of a complex system. Typically, data in these regions, if available at all, consist of point measurements at sparse moorings or 2D profiles of a snapshot in time. Here we present a methodology using monoscopic time-lapse imagery to characterise fjord circulation at the mouth of Sermillik Fjord near Helheim Glacier in southeast Greenland. Image resection methods are used to assign a 3D coordinate system to the 6-minute time-lapse images and the movement of icebergs and sea ice are mapped using feature tracking. Along with local wind data, these results will provide much needed information about the patterns of circulation at the fjord’s mouth on the surface and at depth, ice fluxes and the influence of wind.