Contributions of Altimetry and Argo to Non‐Closure of the Global Mean Sea Level Budget Since 2016

Abstract Over 1993–2016, studies have shown that the observed global mean sea level (GMSL) budget is closed within the current data uncertainties. However, non‐closure of the budget was recently reported when using Jason‐3, Argo and GRACE/GRACE Follow‐On data after 2016. This non‐closure may result from errors in the data sets used to estimate the GMSL and its components. Here, we investigate possible sources of errors affecting Jason‐3 and Argo data. Comparisons of Jason‐3 GMSL trends with other altimetry missions show good agreement within 0.4 mm/yr over 2016–present. Besides, the wet tropospheric correction uncertainty from the Jason‐3 radiometer contributes to up to 0.2 mm/yr. Therefore, altimetry alone cannot explain the misfit in the GMSL budget observed after 2016. Argo‐based salinity products display strong discrepancies since 2016, attributed to instrumental problems and data editing issues. Reassessment of the sea level budget with the thermosteric component provides about 40% improvement in the budget closure.