Regional Assessment of Sea Level Variability from the ORA-IP multi-reanalyses ensemble study

Eighteen ocean reanalyses and three sea level observation derived products are collected as part of the CLIVAR GSOP ORA-IP [Balmaseda et al., 2015]. Ocean synthesis on monthly basis can be performed by studying jointly heat content [Palmer et al., 2015], salt content, sea level (SL), and steric height [Storto et al., 2015] contributions to ocean interannual and seasonal variability. SL variability is primarily provided by altimeter derived products, e.g;, from AVISO or ESA-CCI projects. We discuss here the benefit of ensemble approaches, and the added value of reanalysis products for assessing SL variability and patterns. Focus is made on the North, Tropical and South Atlantic basin, as well as in the Pacific Tropical band. Depending on modelling and assimilation approaches, reanalyses reliability for SL assessment differs, but the most realistic ocean reanalyses offer the benefit of consistent SL and water mass distribution for evaluating relative contribution of volume and mass changes. These patterns can also be independently assessed using GRACE derived ocean mass fluctuations at regional scale.

Balmaseda, M.A., et al. The Ocean Reanalyses Intercomparison Project (ORA-IP), Journal of Operational Oceanography, 8:sup1, s80-s97, 10.1080/1755876X.2015.1022329, 2015.

Palmer, M.D., et al. Ocean heat content variability and change in an ensemble of ocean reanalyses, Climate Dynamics, 1-22, 10.1007/s00382-015-2801-0, 2015.

Storto, A., et al., Steric sea level variability (1993–2010) in an ensemble of ocean reanalyses and objective analyses, Climate Dynamics, 1-21, 10.1007/s00382-015-2554-9, 2015.