The onset of a surge in Dyngjujökull outlet glacier in N-Vatnajökull, Iceland

Dyngjujökull is a surge-type outlet glacier, which in 2025 covered ~1030 km2, corresponding to more than 1/8 of Vatnajökull ice cap. Dyngjujökull has a surge interval of 20–30 years with the last surge occurring in 1998–2000. During that surge, ~12 km3 of ice was transported from Dyngjujökull’s reservoir area to the receiving area and the glacier margin advanced by ~2 km. The motion of Dyngjujökull has been measured at mass-balance stakes near its centre flow line since 1993. In spring 2025, a GNSS station was deployed at stake location D7, at elevation 1350 m a.s.l., slightly above the glacier equilibrium line. The velocity at this site had in recent years been gradually increasing from 60 to 90 m a–1 repeating similar development as observed prior to the last surge. The measured average velocity at D7 in the summer 2025 was 150 m a–1, approximately the same as observed at the start of the last surge in summer 1998, strongly indicating the onset of a new surge. Here we will present the evolution of ice motion of Dyngjujökull at the start of this surge, in winter 2025–26, extracted from multiple radar satellites, including ICEYE, Sentinel-1, TerraSAR-X/TanDEM-X and SAOCOM, and GNSS stations operated on the glacier. We also aim to present elevation changes deduced from Pléiades satellite DEMs planned for February to April, 2026.