Rising sea level is a growing threat to coastal areas across the globe. Despite this, sea level changes at the coast remained poorly characterised, until now.
To date, there has been a lack of systematic coastal sea level observations along most of the world coastlines. To address this issue, the research team created a novel altimetry-based coastal sea level data set consisting of high-resolution (~300 m) monthly sea level data along the satellite tracks, at distances of less than 3-4 km from the coastlines in general, at some locations even closer, within 1-2 km from the coast.
This data set is based on a complete reprocessing of raw radar altimetry waveforms (a process called ‘retracking’) from the Jason-1, Jason-2 and Jason-3 missions.
The data set provides coastal sea level trends over 2002-2018 at 429 coastal sites across the Northeast Atlantic, Mediterranean Sea, West Africa, North Indian Ocean, Southeast Asia and Australia.
Interestingly, the coastal sea level trends show no significant difference (within +/-1 mm/yr) with open ocean trends for 80% of the studied sites - a totally unexpected result considering the theoretical predictions about the potential influence of small-scale coastal processes. However, this was found not to be true everywhere. Indeed, at a few sites, the team observed a larger sea level trend close to the coast than offshore, while in some other cases, a decrease in trend is observed as the distance to the coast decreases. Causes of such trend departures remain to be studied.
Benveniste, J., Birol, F., Calafat, F. et al. Coastal sea level anomalies and associated trends from Jason satellite altimetry over 2002–2018. Sci Data 7, 357 (2020).https://doi.org/10.1038/s41597-020-00694-w
SEANOE repository - https://doi.org/10.17882/74354
CCI Sea level project information - https://climate.esa.int/en/projects/sea-level/