Shifts of the Recirculation Pathways in Central Fram Strait Drive Atlantic Intermediate Water Variability on Northeast Greenland Shelf

Abstract

Increased oceanic heat transport plays a key role in the accelerated mass loss of Greenland's marine‐terminating glaciers. The melt rate of major glaciers in Northeast Greenland (NEG) is controlled by ocean variability, in particular warm Atlantic Intermediate Water (AIW), on the continental shelf. A high‐resolution configuration of the ocean sea‐ice model FESOM2.1 is assessed at local and regional scales, and used to investigate the drivers of AIW temperature variability on the NEG continental shelf. The seasonal to decadal variability of AIW is characterized, featuring both pronounced interannual fluctuations and a long‐term warming trend. A major source of AIW is Atlantic Water (AW) originating from the West Spitsbergen Current that recirculates in Fram Strait. AW anomalies are advected westwards and partly control the AIW temperatures on the continental shelf. Increased AIW temperatures are also connected to pronounced northern and central branches of recirculating AW in Fram Strait, and enhanced AW temperatures more regionally. The strengthening of the pathways brings more warmer AIW onto the northern part of the NEG continental shelf. There, it circulates anti‐cyclonically and results in shelf‐wide warming. Regional atmospheric forcing is connected to the changes in the AW circulation. The strengthening of the northern AW branches is likely caused by anticyclonic wind anomalies over the Barents Sea that drive an enhanced northward AW transport in Fram Strait. Thus, controlled by a combination of both upstream and regionally forced circulation conditions, the changes in local AIW temperatures may also affect the oceanic heat transport reaching the Central Arctic Ocean.