Structure of Boundary Current in the Nansen Basin of the Arctic Ocean

It is believed that circulation of the intermediate (150-800m) water of Atlantic origin (the so-called Atlantic Water, AW) in the eastern Arctic Ocean is topography-steered confining with deep-basin margins and enveloping the shelf breaks. However, recent observations from Fram Strait show barotropic structure of water transport. Mooring records from Svalbard area (~30E) show very different structure of flow with a maximum velocity at ~200m in the AW core. Mooring observations over the Laptev slope showed erosion of the AW jet-like flow and further eastward observations at the Lomonosov Ridge found a barotropic flow with velocity generally decreasing with depth. Modeling results suggest the existence of topographically-controlled two-core along-slope flow near the Spitsbergen slope. The shallow core is located over the shelf break at ~400m. The second core is shifted in the basin interior and located at ~1200m. Similar to observations, the vertical structure of deeper branch of AW flow has a maximum at an intermediate depth caused by baroclinic balance of forces. This finding may be important for interpretation of warm AW pulses in the Arctic Ocean interior.