Relative Contributions of Ocean Mass and Deep Steric Changes to Sea Level Rise Between 1993 and 2013

Regional and global trends of Sea Level Rise (SLR) owing to mass addition centered between 1996 and 2006 are assessed through a full-depth SLR budget using full-depth in situ ocean data and satellite altimetry. These rates are compared to regional and global trends in ocean mass addition estimated directly using data from the Gravity Recovery and Climate Experiment (GRACE) from 2003 to 2013. Despite the two independent methods covering different time periods with differing spatial and temporal resolution, they both capture the same large-scale mass addition trend patterns including higher rates of mass addition in the North Pacific, South Atlantic, and the Indo-Atlantic sector of the Southern Ocean, and lower mass addition trends in the Indian, North Atlantic, South Pacific, and the Pacific sector of the Southern Ocean. The global mean trend of ocean mass addition is 1.5 (±0.4) mm yr ⁻¹ for 1996–2006 from the residual method and the same for 2003–2013 from the GRACE method. Furthermore, the residual method is used to evaluate the error introduced into the mass budget if the deep steric contributions below 700, 1000, 2000, 3000, and 4000 m are neglected, revealing errors of 65%, 38%, 13%, 8%, and 4% respectively. The two methods no longer agree within error bars when only the steric contribution shallower than 1000 m is considered.