MIXSED postdoc opportunity at AWI

8 July 2025

Photo: Wilken-Jon von Appen

F4 triangle array in Fram Strait, July 2024-July 2026

One of the source regions of North Atlantic Deep Water is the Nordic Seas. Water flows northward in the Norwegian Atlantic Slope and Front Currents and gets cooled and densified by strong atmospheric heat loss. This water then leaves the surface in Fram Strait between Greenland and Svalbard in a region where the horizontal density gradient at the surface is large. The water then flows southward and eventually crosses the Denmark Strait upon which it descends along the seafloor as a gravity plume. Along this pathway the water is subject to water mass transformation associated with submesoscale instabilities: In Fram Strait those submesoscale instabilities take place in the surface mixed layer and south of Denmark Strait those submesoscale instabilities take place in the bottom mixed layer, where the strong flow also affects sedimentation. A collaborative project funded by the German Deutsche Forschungsgemeinschaft (DFG) and the Spanish Agencia Estatal de Investigación (AEI) called Mixsed (“Mixing and Sediment Dynamics”) aims to understand this water mass transformation. The Alfred Wegener Institute (AWI) (PI Wilken-Jon von Appen) has deployed a mooring array resolving submesoscale gradients in the surface mixed layer in the eastern Fram Strait in summer 2024 which will be recovered in summer 2026. The University of Hamburg (PI Eleanor Frajka-Williams) will deploy a mooring array resolving submesoscale gradients in the bottom mixed layer south of Denmark Strait for spring to fall 2026. Further shipboard activities in Denmark Strait will target associated sediment dynamics (PIs David Amblas, Anna Sànchez Vidal, Maria Dolores Pérez Hernández).
Here, we advertise a Postdoc position within MixSed work package 1 at AWI that will analyze the mooring data in Fram Strait. A particular focus will be on quantifying the temporal variability from hours to seasons of the submesoscale gradients in the surface mixed layer in Fram Strait. This will be used for dynamical analyses (for example the analyses might be similar to these studies: DOI:10.1175/JPO-D-18-0253.1, DOI:10.1175/JPO-D-21-0099.1, DOI:10.1175/JPO-D-15-0170.1) revealing processes participating in the water mass transformation. The Postdoc may participate in the shipboard work in Denmark Strait and Fram Strait in 2026 (mooring deployment and recovery). Historical data from those areas may also be analyzed to better quantify the background conditions that the novel submesoscale resolving observations are embedded in. The Postdoc will closely collaborate with the PIs and with a Postdoc at the University of Hamburg who will perform similar analyses using the data from the bottom mixed layer in Denmark Strait.