Grounding line migration and high‐resolution calving dynamics of Jakobshavn Isbræ, West Greenland

摘要: [1] We performed three field campaigns in 2004, 2007, and 2010 at the southern margin of Jakobshavn Isbrae, West Greenland, order to infer flow velocities their changes from photogrammetric time-lapse imagery with a temporal resolution 20 min spatial spacing about 30 m on glacier surface. Area-wide analysis more than 3000 three-dimensional trajectories individual positions allow for both mapping grounding line detailed observation variations during major calving events. From 2004 2010, Isbrae retreated 3.5 ± 0.2 km. Considering previously published results, retreat amounts 6 km since 1985. The has an ephemeral floating tongue that can establish readvance front break apart after large Observations event show acceleration coincides onset up which 70 m/d be reached. Moreover, vertical displacements 15 m lowering 8 m 500 m beyond were observed 2 days before event. After up, slowly adjusts new boundary conditions within next 4–5 days. Flow velocity caused by detected 1 km upstream only indicates events have no immediate effect large-scale dynamics.