Boundary wave communication of bottom pressure and overturning changes for the North Atlantic

The relationship between changes in sea-surface height, bottom pressure, and overturning is explored using isopycnal model experiments for the North Atlantic. Changes in high-latitude forcing are communicated rapidly over the basin through boundary wave propagation along the continental slope, involving a hybrid mixture of Kelvin and topographic Rossby waves, as well as spreading more slowly through advection along the western boundary. This wave communication leads to coherent signals in sea-surface height and bottom pressure variability extending for several thousand kilometers along the continental slope. The model results are in broad agreement with altimetric diagnostics, and the patterns only alter in detail with the realism of the topography. The adjustment in bottom pressure is directly linked to a change in overturning since west-east contrasts in bottom pressure are associated with a zonal integral in the meridional geostrophic flow. Correlation patterns reveal that temporal changes in overturning are primarily connected to the vertical contrast in bottom pressure, across the shelf and continental slope, along the western boundary.