20-year-long sea level changes along the world’s coastlines from satellite altimetry: a new data set of coastal virtual stations

In the context of the ESA Climate Change Initiative (CCI) Coastal Sea Level project, a complete reprocessing (including retracking of the radar waveforms) of high resolution (20 Hz, i.e. 350 m) along-track altimetry data of the Jason-1, Jason-2 and Jason-3 missions since January 2002 was performed along the world coastal zones. Different versions have been provided so far. The latest release (SL_cci+ coastal altimeter sea level dataset, v2.3) is now available to users. It is an extension in time of the previous data set (v2.2) which covers the period January 2002 to June 2021. A new improved processing for the waveform retracking and computation of the coastal sea level anomalies was developed and a new editing procedure for the coastal sea level trend computation was implemented. This new data set shows spectacular reduction of the data noise compared to previous versions, both in terms of sea level anomaly time series and trends. As a consequence, compared to the previous versions we now obtain an important increase of the number of virtual coastal stations (i.e., the location of the first valid point along the satellite track, with about 1200 sites at an average distance from the coast of about 3 km, including more than 200 stations at less than 2 km from the coast). The coastal sea level anomalies and trends of the altimetry-based virtual stations have been validated with tide gauge data where possible. An example in the Mississippi Delta is presented.