Closing the Global Sea Level Rise Budget with GRACE, Argo, and Altimetry Observations

An important goal of climate studies is to determine the relative contribution of steric (heating and salinty) and eustatic (melting ice, runoff) sea level rise and to understand how and why these contributions vary. Concurrent measurements from the Argo array of profiling floats and the GRACE gravity mission, which respectively measure steric and eustatic changes, provide an independent measure of total sea level change. An analysis of the steric and ocean mass components of sea level shows that the sea level rise budget for the period January 2004 to December 2007 can be closed. Using corrected and verified Jason-1 and Envisat altimetry observations of total sea level, upper ocean steric sea level from the Argo array, and ocean mass variations inferred from GRACE gravity mission observations, we find that the sum of steric sea level and the ocean mass component has a trend of 1.5 ± 1.5 mm/year over the period, in agreement with the total sea level rise observed by either Jason-1 (2.2 ± 1.6 mm/year) or Envisat (1.7 ± 1.8 mm/year). This provides verification that the altimeters, Argo buoys, and GRACE are providing consistent results and opens the way to routine monitoring of the major components of sea level rise.