Variability of North Atlantic Water Mass Properties along Western Boundary and Interior Pathways

The Atlantic Meridional Overturning Circulation (AMOC) exports cold, fresh, dense waters formed in the subpolar North Atlantic to equatorward latitudes along the western boundary and interior pathways. The properties of the water formed in the North Atlantic vary from year to year, however the strength and time scale for the downstream communication of this variability is still unclear. While several past studies have focused on tracking specific property anomalies, particularly from the Labrador Sea, we approach our study by investigating property variance downstream of the water mass source region. In effect, we aim to understand the downstream memory of water mass property variability in the North Atlantic along western boundary and interior pathways. To do so, we analyze hydrographic properties on neutral density isopycnal surfaces in the subpolar North Atlantic and along the western boundary and interior pathways with two reanalysis products from the Met Office, the hydrographic dataset (EN4) and ensemble prediction system (GloSea5), over their overlapping time period (1993-2019). Our results show different patterns of downstream variance for the interior compared to the western boundary, which we interpret in terms of known circulation features in the deep North Atlantic and what we have learned from past Lagrangian studies.