(Lompoc) The European Space Agency’s EarthCARE satellite took off from California on Tuesday to explore in detail the effects of clouds on the climate, still poorly understood despite their key role.
The launch took place from Vandenberg Air Force Base in the western United States at 3:20 p.m. local time (6:20 p.m. Eastern Time) aboard a rocket Falcon 9 from SpaceX. “We have started our flight,” the European Space Agency (ESA) immediately wrote on its website.
The 2.2-ton satellite designed by Airbus will operate 400 kilometers above Earth. It must “revolutionize” our understanding of the effects of clouds on the climate – sometimes cooling, sometimes warming – according to the ESA.
“Tonight’s liftoff reminds us that space is not only dedicated to the exploration of distant galaxies and planets, but also to the understanding of our beautiful and fragile Earth,” said in a video published Tuesday on the social networks Josef Aschbacher, the director of the ESA.
Cumulus, cirrus, cumulonimbus… clouds are complex objects which act differently on the climate depending on their altitude in the troposphere, the lowest layer of the atmosphere.
They “are one of the main contributors to climate change and it is one of those that we know the least about”, explained to AFP Dominique Gilliéron, head of the observation projects department of the ESA Land.
Some, like cumulus clouds, formed of water vapor and located quite low, work like a parasol: very white and very bright, they reflect the Sun’s radiation back into space –– an effect called albedo – and cool the atmosphere. .
Others, like high-altitude cirrus clouds, made of ice – very thin clouds whose thin veil can be seen from an airplane – on the contrary allow solar radiation to pass through, which warms the Earth. The latter re-emits thermal radiation that “the cirrus clouds will capture, which keeps the heat in, like a survival blanket,” explained Dominique Gilliéron during a press conference.
Hence the importance of evaluating the nature of clouds according to altitude by dissecting their vertical structure, which no satellite has done until now, underlined Simonetta Cheli, director of observation programs at the Earth at ESA.
“Parasol” or “cover” effect
The mission, in collaboration with the Japanese agency Jaxa, will also study aerosols, tiny suspended particles (dust, pollen, human pollutants such as combustion ashes, etc.), on which water condenses and which are precursors of clouds.
EarthCARE’s two “active” instruments will send their light toward the clouds and calculate the time it takes to return.
Lidar (“Laser imaging detection and ranging”) will emit ultraviolet light to study fine high-altitude clouds and aerosols.
The radar will be able to “see through” the opaque layers of clouds to determine their solid water composition (in the form of droplets).
EarthCARE is also equipped with a multispectral imager, which will provide information on the shape of clouds, and a radiometer to probe their temperature.
All the physical parameters of the clouds will thus be measured below the satellite simultaneously, a first.
Information “highly awaited”, according to the ESA, by the scientific community, which seeks to refine its climate models to assess the Earth’s radiative balance, that is to say the balance between the radiation that our planet receives, coming from the Sun, and those it emits.
With the idea of predicting “if the current effect of the clouds, which is rather cooling at the moment […] will strengthen or weaken,” explained Dominique Gilliéron.
For the moment, the “parasol trumps the cover” effect he compared? But the evolution is uncertain, because global warming is changing the distribution of clouds.
The European mission, planned for three years, takes over from NASA’s CloudSat and CALIPSO satellites, whose missions have now ended.