These links relate to the Sea Level project.

More on altimetry:

Other websites related to mean sea level:

The reference global mean sea level (GMSL) based on data from the Topex/Poseidon, Jason-1, Jason-2 and Jason-3 missions from January 1993 to present (annual and semi-annual signals removed, 6-month filtered, corrected for a postglacial rebound correction of -0.3 mm/yr).

Regional gridded sea level trend over the period 1993-to present (in mm/year) from the multi-mission Ssalto/Duacs data.

Focus on the current SL_cci achievements

The current phase of the project focuses on the estimate of the sea level close to the coast in order to assess whether the sea level trends at the coast are similar to what can be observed further offshore in the open ocean.

Reprocessed altimeter 10-day Sea Level Anomalies have been computed in all the coastal regions illustrated below.

Regions covered in version 2.1

Then, further validation and editing have led to the production of the v2.1 dataset of monthly sea level anomalies and associated trends at 756 selected coastal sites located in almost all the world coastal ocean (see below) covering 2002-2020.

Closest distance to coast reached by the first valid point along the track at the 756 coastal sites (called ‘virtual coastal stations’ v2.1)

The mean sea level trends observed at the 251 virtual stations located at less than 3.5 km from the coast are shown below during 2002-2020, superimposed with the C3S sea level trends during the same time span.

Coastal mean trends (average over the first 2 km along the track) computed over January 2002 to December 2019 for the 251 virtual stations located at less than 3.5 km from the coast. The background map represents the C3S sea level trends over the same time span.

In more than 80% of cases, the sea level trend at the coast is similar to the open ocean trend (considered here at a distance of 15 km from the coast). In the other 20%, we note smaller trend than offshore for ¾ of the sites. This is particularly seen in the southeast Asia region. The remaining sites show slightly larger trends in the last few km to the coast compared to the open ocean. Illustration of the different trend behaviours is presented below as well as a map synthsizing the results.

Examples of sea level trend behaviours approaching the coast (constant, increasing and decreasing).

Sites where coastal trends differ from offshore trends. Red/blue triangles correspond to increasing/decreasing trends near the coast.

The network of virtual coastal stations proposed here should be of invaluable interest for estimating present-day (absolute) sea level rise along the world coastlines, especially in regions devoid from in situ tide gauges. This is illustrated below with the distribution of the 271 virtual stations located within 3.5 km from the coast and of current tide gauges that have monthly sea level data over the study time span (with not more than 24 months of missing data).

Network of 271 virtual coastal stations located within 3.5 km from the coast (green dots) with tide gauges (from PSMSL) having monthly data over 2002/01-2019/12 (with only 24 months of missing data; 400 sites; white/red squares)