I wonder, Paul (@WebHubTel), whether this kind of analysis could be adapted to studies of the North Wall of the Gulf Stream, per https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-18-0212.1 or Wolfe, Hameed, Chi, "On the drivers of decadal variability of the Gulf Stream North Wall", *Journal* *of* *Climate*, February 2019. They are looking at frequency domain connections between North Wall variability and NAO as well as the less well known Atlantic meridional mode (AMM) which is an equatorial process in the Atlantic. The Stream and its North Wall are important for Northeastern U.S. weather as well as primary production in the region.