A subannual subsurface pathway from the Gulf Stream to the Subpolar Gyre and its role in warming and salinification in the 1990s

The transport of warm, saline subtropical water to the subpolar gyre (SPG) in the North Atlantic has been the subject of a range of Lagrangian studies, establishing intergyre exchange on timescales of 2–7 years, with greater subsurface throughflow. Here calculating particle trajectories in a high‐resolution, global hindcast, we present new evidence for a direct, subsurface pathway to the SPG from the Gulf Stream (GS) on subannual timescales. The pathway is most evident for particles initially at 200‐m depth in the GS and is enhanced after a prolonged period of positive North Atlantic Oscillation. This occurred in the mid‐1990s and led to warming and salinification of the western SPG consistent with observations. The more realistic advective pathways and timescales in the high‐resolution model enable, for the first time, attribution of temperature and salinity changes in the SPG to a direct influx of GS water.