Steric sea level variations over 2004-2010 as a function of region and depth: Inference on the mass component variability in the North Atlantic Ocean

Abstract

We investigate the regional-ocean depth layer (down to 2000 m) contributions to global mean steric sea level from January 2004 to March 2010, using Argo-based ocean temperature and salinity data from the SCRIPPS Oceanographic Institution database. We find that Indian ocean warming is almost compensated by Atlantic ocean cooling, so that the total global mean steric sea level increases only slightly over the considered period (0.35 ±0.30 mm/yr). Salinity variations also contribute, at lower rate, to the observed steric compensation. Meanwhile, the Pacific steric sea level increases only slightly (0.35 ±0.25 mm/yr). In the North Atlantic region, the mass component (estimated by the difference between satellite altimetry-based minus steric sea level over the same area) is negatively correlated over 2004-2010 with the steric component. During that period, North Atlantic sea level variability seems mostly driven by the North Atlantic Oscillation (NAO). This is unlike during the previous years (1997 to 2004), a period during which we observe significant correlation between North Atlantic sea level and El Nino-Southern Oscillation (ENSO), with positive sea level corresponding to ENSO cold phases (La Nina). Copyright 2011 by the American Geophysical Union.