Validation of Satellite Altimetry for Coastal Storm Surge Detection

A critical manifestation of anthropogenic climate change is the intensification of extreme weather events, particularly storm surges. Driven primarily by strong winds and atmospheric pressure fluctuations associated with severe storm systems, storm surges can devastate coastlines through a rapid rise in sea level. Much of the current research using altimetry to monitor storm surges focuses on localized case studies and utilizes a combination of in-situ, model-generated, and remote sensing data. The overarching objective of this research is to develop a global approach for monitoring extreme sea level events at the coast using altimetry-derived sea level anomaly (SLA) and wave parameters. This study focuses on assessing the capability of altimetry-derived products to detect storm surge events through validation against in-situ observations and reanalysis data. The data used in this project are 20 Hz, along-track altimetry data sourced from the ESA Climate Change Initiative (CCI)¹ Sea State and Sea Level products. Supplementary datasets used for validation purposes are tide gauges sourced from the GESLA-4² dataset and reanalysis data from the hydrodynamic model, GTSMv3.0³. The analysis approach entails performing extreme value statistics on tide-gauge and GTSM data to flag potential surge days, then evaluating individual altimetry tracks on flagged days for signatures of storm surges, then computing wave parameters to improve surge identification. Initial results demonstrate that 20 Hz coastal SLA data can successfully detect storm surge events. However, the intensity and appearance of the surge signature are contingent on the temporal alignment between the surge peak and the satellite pass. The evaluation framework supports the integration of altimetry products into digital flood models, enhancing the ability to quantify coastal risk and predict the impacts of extreme sea-level events. The work contributes to the broader climate adaptation strategies within the European Space Agency (ESA) FRACCEO⁴ project in collaboration with Deltares in Delft, the Netherlands, TU Delft in Delft, the Netherlands, and the Nansen Environmental and Remote Sensing Center in Bergen, Norway.

¹https://climate.esa.int/en/projects/
²https://gesla787883612.wordpress.com/
³https://www.deltares.nl/en/expertise/projects/global-modelling-of-tides-and-storm-surges
⁴https://climate.esa.int/en/supporting-the-paris-agreement/fracceo/