Using satellite sea level tracking to anticipate storms and protect coastal areas

The ongoing 2024 Atlantic hurricane season is leaving a lasting footprint due to the resulting fatalities and infrastructure damage in coastal zones. Timely forecasts of extreme sea levels are crucial to mitigate the imminent risk that challenges the capacity of emergency response systems. 

To help counter this increasing risk, scientists from the Joint Research Centre, CEDEFOP, LEGOS (France), and USC (USA) developed a global model to improve predictions of sea levels. The model incorporates satellite measurements with local atmospheric conditions.

The increasing intensity of extreme events 

There is an increasing consensus that human-caused global warming has intensified recent hurricanes, driving more frequent and more energetic episodic sea level along the global coastal zone.

​​For example, Hurricane Beryl, on which Copernicus prepared emergency maps, made history as the earliest Category 5 Atlantic hurricane on record. Category 4 Hurricanes Helene and Kirk along with Category 5 Hurricane Milton resulted in an aftermath totalling over 264 fatalities and costing $172 billion in damage.​ 

As a result, forecasting where and when natural disasters are likely to occur is critical, and satellite measurements, with their global ocean coverage, can be key to making these forecasts more accurate. 

Overcoming satellite limitations to better predict disaster  

Satellites can provide information about the sea level across the world’s oceans, despite their temporal scarcity due to the long and variable revisit times of each satellite mission. 

Aiming to overcome this limitation, which is important for identifying extreme episodic sea levels, the Joint Research Centre, CEDEFOP, LEGOS (France), and USC (USA) conducted an analysis relying only on publicly available satellite-derived measurements from 23 missions - including those from the Copernicus Contributing Missions. 

The analysis led to a continuous in-time description of the open ocean sea level for a period of 63 years, revealing both the areas of the general circulation ocean currents and the areas exposed to intense tropical cyclone activity. 

Improving sea level prediction to better protect coasts

The efficacy of the proposed methodology for real-time sea level forecasts was demonstrated by estimating the sea level triggered by Tropical Cyclone Kong-rey – the most powerful tropical cyclone worldwide in 2018.  

Using 51 atmospheric forecast scenarios and the satellite data-driven model, the researchers estimated both with high accuracy and high likelihood the tropical cyclone-induced peak sea level and footprint on the sea surface, three days before it made landfall in Japan. 

This low-computational-cost method may serve as a complementary tool to conduct rapid analyses of global and local coastal risk. On a later occasion, the model output was again deployed in September 2024 to anticipate the path and severity of hurricanes Helene, Milton and Kirk. 

Text version

Since December 2023, the approach of the study has been applied to derive 15-day and 3-month sea level forecasts for the global ocean. It supported  timely medium-term and long-term response actions to mitigate sea level impacts along the global coastal zone. 

Background 

This model has been used to generate both 15-day and 3-month sea level forecasts since December 2023. 

The medium-term sea level forecast was used in early July 2024 in order to support the Joint Research Centre’s Emergency Report for the landfall of Hurricane Beryl in the Caribbean Sea. 

Both the hindcast and the real-time forecasts of the global ocean sea level will soon be available through the Joint Research Centre Data Catalogue.