Pathways and Upstream Origins of Warming Dense Waters Supplying the Faroe Bank Channel Overflow

Dense, cold water passes through the Faroe Bank Channel contributing to the lower branch of the Atlantic Meridional Overturning Circulation. Observations show that the bottom water warmed at an average rate of 0.1C per decade since the early 2000s. Using GLORYS12 reanalysis (1/12), we find that it captures the observed variability, including warming and a lagged salinification trend. To investigate the sources and pathways of warming dense bottom waters, we use GLORYS12 output and seed Lagrangian particles in the Faroe‐Shetland Channel (FSC) from 2000 to 2020, backtracking them for 10 years. We find two upstream flow pathways, one via the East Greenland and one through the Jan Mayen (JM) Channel. These two source flows converge, both via cyclonic circulation around the Iceland Sea into the East Icelandic Current (EIC), and where the EIC and southward flow along the JM Ridge merge. The total western‐sourced overflows subsequently follow the north slope of the Iceland‐Faroe Ridge (IFR) and the Faroe plateau before entering the FSC. Particles either directly enter the FSC or overshoot the channel and recirculate southwards along the Norwegian shelf slope. An additional eastern pathway emerges from a previously overlooked source along the Norwegian shelf slope originating from the Lofoten Basin. The Greenland Sea deep gyre warms faster than other deep regions in the Nordic Seas, but particle transit through the basin center is rapid, indicating limited retention. However, recirculation and lateral exchanges can distribute warmer interior waters from the Greenland Sea into surrounding basins.