Will clouds help cool or warm our world in the years ahead? The EarthCARE satellite is getting ready for lift-off on a SpaceX Falcon 9 from Vandenberg, California, with a target launch date of no earlier than 28 May 2024. Developed as a cooperation between ESA and the Japan Aerospace Exploration Agency (JAXA), EarthCARE will examine the role that clouds and aerosols play in reflecting solar radiation back into space and also in trapping infrared radiation emitted from Earth’s surface.
The two-tonne satellite will orbit nearly 400 kilometers above Earth for three years, building a complete profile of those fluffy clouds over our heads.
“They are one of the main contributors to how the climate changes — and one of the least understood,” Dominique Gillieron, head of the ESA’s Earth observation projects department, told Agence France-Presse.
Clouds — from cumulus and cirrus to cumulonimbus — are a varied and complicated phenomenon. Their composition depends on where they are located in the troposphere, Earth’s lowest layer of atmosphere, Gillieron explained.
The troposphere starts at around eight kilometers above the polar regions, but near the equator, it begins at around 18 kilometers up. This means that clouds affect the climate differently depending on their altitude and latitude.
For example, white and bright cumulus clouds, which are made out of water droplets, sit quite low and work like a parasol, reflecting the Sun’s radiation back into space and cooling the atmosphere.
Higher up, cirrus clouds made of ice crystals allow solar radiation to pass through, heating up our world. Cirrus clouds then trap in the heat like a “blanket,” Gillieron said.
EarthCARE will become the first satellite to measure the vertical and horizontal distribution of clouds, she told a press conference. Two of the satellite’s instruments will flash light at the clouds to probe their depths.
The Lidar instrument will use a laser pulse to measure clouds and aerosols, tiny particles in the atmosphere such as dust, pollen, or human-emitted pollutants like smoke or ash.
Aerosols are the “precursors” to clouds, Gillieron explained.
The satellite’s radar will pierce through the clouds to measure how much water they contain. It will also track the speed of the clouds moving through the atmosphere, similar to how radar helps police nab speeding cars.
The amount of solar radiation that passes through Earth’s clouds could, therefore, be crucial to understanding and mitigating the impact of human-driven global warming.
The mission aims to find out “whether the current effect of the clouds, which is rather cooling at the moment — the parasol outweighs the blanket — will become stronger or weaker,” Gillieron said.
This trend has become more difficult to predict as global warming has changed the distribution of clouds. “EarthCARE is being launched at an even more important time than when it was conceived in 2004,” Cheli said.
