EarthCARE satellite to probe how clouds affect climate May 26, 2024

Clouds can both protect the Earth from the Sun's radiation and trap it like a blanket, say scientists (Daniel ROLAND)

By AFP - Agence France Presse

EarthCARE satellite to probe how clouds affect climate

Will clouds help cool or warm our world in the coming years? The EarthCARE satellite will soon set out on a mission to find out, to investigate the role clouds can play in the fight against climate change.

The collaboration between the European Space Agency and the Japanese space agency JAXA is scheduled to launch on Tuesday on a SpaceX Falcon 9 rocket from the Vandenberg base in California.

The two-ton satellite will orbit about 400 kilometers (250 miles) above the Earth for three years, tracing a complete profile of these fluffy clouds over our heads.

“They are one of the main factors contributing to climate change and one of the least understood,” Dominique Gillieron, head of ESA's Earth observation projects department, told AFP.

Clouds - from cumulus and cirrus to cumulonimbus - are a varied and complicated phenomenon.

Their composition depends on where they are located in the troposphere, the lowest layer of the Earth's atmosphere, Gillieron explained.

The troposphere begins about eight kilometers (five miles) above the polar regions, but near the equator, it begins about 18 kilometers (11 miles) above. This means that clouds affect the weather differently depending on their altitude and latitude.

For example, the bright white cumulus clouds, which are made up of water droplets, sit very low and act like an umbrella, reflecting the Sun's radiation into space and cooling the atmosphere.

Higher up, cirrus clouds, made of ice crystals, allow solar radiation to pass through, warming our world.

The cirrus clouds then trap the heat like a “blanket”, said Gillieron.

- Parasol or blanket? -

Therefore, understanding the nature of clouds has become very important, said Simonetta Cheli, head of ESA's Earth observation programs.

EarthCARE will be the first satellite to measure the vertical and horizontal distribution of clouds, she told a press conference.

Two of the satellite's instruments will emit flashes of light on the clouds to probe their depths.

The Lidar instrument will use a laser pulse to measure both clouds and aerosols, which are tiny particles in the atmosphere such as dust, pollen, or man-made pollutants like smoke or ash.

Aerosols are the “precursors” of clouds, Gillieron explained.

The satellite's radar will pass through the clouds to measure the amount of water they contain.

It will also track the speed of clouds moving through the atmosphere, in a similar way to how radar helps police detect speeding cars.

The satellite's other instruments will measure the shape and temperature of the clouds.

All this data will create the first complete image of clouds from the perspective of a satellite.

The scientific community is eagerly awaiting this information so that it can update climate models that estimate how quickly our world will warm up, said ESA.

The amount of solar radiation passing through the Earth's clouds could therefore be crucial to understanding and mitigating the impact of man-made global warming.

The mission aims to find out “whether the current effect of clouds, which is cooling down a lot at the moment - the umbrella outweighs the blanket - will get stronger or weaker,” said Gillieron.

This trend has become more difficult to predict as global warming has altered the distribution of clouds.

“EarthCARE is being launched at an even more important time than when it was conceived in 2004,” said Cheli.

juc/dl/cw