Heat waves under close surveillance from space

How is ESA, the European Space Agency, monitoring the heat waves that have affected Western Europe for weeks? In a video, Clément Albergel, CNRS Research Fellow currently seconded to ESA, describes the different solutions implemented to closely monitor the effects of drought and very high temperatures in the region. And put it all into perspective with data collected over decades.

“The many heat waves that have occurred in Western Europe are a clear sign of global warming caused by human activities and the resulting greenhouse gas emissionsexplains Clément Albergel. To better understand the variations in our climate system, we need to observe this from space, especially thanks to the European satellites that are part of the Copernicus programme. They have the advantage of providing global coverage, uniform analysis but also fast and continuous measurements.

Data from the Copernicus program covers the entire planet. Credit: ESA.

Sentinel satellites deployed to observe Earth

In the family of Sentinel satellites, which has six different models, Sentinel-3 is particularly useful. For example, it is able to examine the surface of the ocean and measures its surface temperature using a radiometer. It also monitors sea and land surface colors with great precision. “During the last two weeks of July, Sentinel-3 measured record heat on the Earth’s surface. Over 45°C in the UK, over 50°C in France and over 60°C in Spain”emphasizes Clément Albergel.

In addition, the Copernicus program combines data from various satellites and data taken directly on Earth to identify major global changes over time and to better understand the current phenomenon of global warming. ESA recently unveiled a report that puts into perspective 25 years of Earth temperature measurement data. Results: “an average increase of 0.2°C per decade globally, but with large regional differences”summarizes the CNRS researcher seconded to ESA.

A satellite device that is also capable of monitoring forest fires

The Copernicus program is also able to provide high monitoring of natural disasters such as the recent forest fires in the Gironde. An accurate and near real-time device that helps firefighters in their fight against fire.

“Satellites are very useful because they are able to follow the different characteristics of a brand. From a risk point of view, they can identify the areas most prone to fires because they are particularly dry. We can also monitor fires, whether it’s the gaps in the grip of the flames or the overall extent of the damage thanks to the tracks that are visible from space.”notes Clément Albergel.

A forest fire under close surveillance from space.  Credit: ESA.
A forest fire under close surveillance from space. Credit: ESA.

Monitor water levels in rivers

Also in drought situations, satellites are useful for assessing the drop in water levels in Europe’s streams and rivers. This is e.g. currently the case for the Loire or the Rhône, which are sometimes almost dry in places and whose flow is very slow. The too shallow draft also prevents river transport on certain parts of these rivers, whether for tourism or goods.

In this case, the Sentinel-2 satellites come into play. “Images taken from space thus show how the Po River in Italy has shrunk enormously between June 2020 and June 2022. This is partly due to the lack of rainfall in Northern Italy in recent years, much less than average. . But also to the heat waves and the absence of snow in the mountains, which generally feed the river”explains Clément Albergel.

The Sentinel-2 satellites closely follow the evolution of rivers, like here the Po in Italy, at the level of Piacenza in Emilia-Romagna.  Credit: ESA.
The Sentinel-2 satellites closely follow the evolution of rivers, like here the Po in Italy, at the level of Piacenza in Emilia-Romagna. Credit: ESA.

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