Ocean dead zones: On the Lack of Sea Surface Height Variability near the Continental Shelf Edge

We analyse the spatial pattern of sea surface height variability (SSV) in the North
Atlantic using monthly data from satellite altimetry (1993-2013). In this dynamically very
active area of the globe the spatial pattern of SSV varies over nearly two orders of
magnitude. We show that remarkably tranquil regions exist, that appear to be ``ocean
dead zones'' as far as their SSV is concerned. Natural hotspots for these quiet waters
are in the vicinity of continental shelf edges where waters are on the one hand deep
enough to be relatively unaffected by atmospheric variability forcing (storm surges
etc.), yet are not affected by variability of deep ocean currents. The low variability
makes these regions near the continental shelf edge ideal for identifying temporal SSH
trends, because of the high signal-to-noise ratio. They are also the key areas where
possible accelerations of the SSH trend, as anticipated in most future climate
projections, can be detected in the observations much earlier than elsewhere.