Benoît Meyssignac (LEGOS/CNES, France); Michael Ablain (Magellium, France); Giorgio Spada (Università di Bologna, Italy); Aurélien Ribes (CNRM, Meteo France, France); Jérôme Benveniste (ESA/ESRIN, Italy)

Satellite altimetry missions provide a quasi-global synoptic view of sea level variations over 27 years and provide regional sea level (SL) indicators such as trends and accelerations. Estimating realistic uncertainties on these quantities is crucial to address current climate science questions. While uncertainty estimates are available for the global mean sea level (GMSL), information is not available at local scales so far.
We estimate a local satellite altimetry error budget and use it to derive local confidence intervals for SL rise rates and accelerations. We estimate the local error variance-covariance matrix, and derive confidence intervals on trends and accelerations at the 90% confidence level.
Error variance-covariance matrices, SL trends and accelerations, along with corresponding uncertainties are provided as a NetCDF file.
Over 1993–2019, we find that the average local sea level trend uncertainty is 0.86 mm/yr with values ranging from 0.8 to 1.3 mm/yr. For accelerations, uncertainties range from 0.06 to 0.13 mm/yr/yr with a mean value of 0.065. We also perform a sensitivity study to investigate a range of plausible error budgets.