Coherent multidecadal variability in North Atlantic sea level

Abstract

Tide gauge records from around the North Atlantic are examined and found to show variability on 20–30 year time scales. Sea surface height variability along the western boundary of the North Atlantic shows a particularly strong and coherent signal. Similar variability is also found in an ensemble of runs using a state-of-the-art climate model (GFDL CM2.1). This sea surface height variability is linked to variability of temperatures in the upper layers of the ocean and thence to the Atlantic Multidecadal Oscillation. The variability is consistent with the excited internal ocean mode mechanism of multidecadal variability derived from idealised models and the timescale is consistent with that derived from observations of sub-surface temperature variability