Space data help unravel the complexities of Earth’s atmosphere
As the impacts of the climate crisis intensify, scientists are using ESA’s Earth observation archives to investigate our atmosphere and how it influences the planet’s changing environment.
The atmosphere is a blend of gases that envelops and protects the planet against heat and radiation emitted by the Sun. It’s composed of five layers: the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
Most satellites orbit in the highest layers of the atmosphere - the thermosphere and exosphere - and atmospheric measurements acquired by satellites focus on the lowest layers: the troposphere and stratosphere.
Emissions from humankind activities are having a long-term impact on this protective blanket. ESA has been helping to track these changes for decades, thanks to a series of remote sensing missions.
One such mission is Envisat, which is no longer operational but is still relevant because of the amount of environmental data it provided during its 10 years of activity. The mission has been key to our understanding of Earth's atmosphere.
For example, one of Envisat's imaging spectrometers provided insights into how greenhouse gases are distributed across the planet. Another spectrometer onboard Envisat the mission to monitor the annual Antarctic ozone hole.
International missions are also improving our understanding of the atmosphere. Japan's GOSAT satellites measure greenhouse gases, clouds and aerosols, while the commercial GHGSat constellation monitors greenhouse gas emissions from industrial sites.
GOSAT and GHGSat data are promoted by ESA's Third Party Missions Programme, which encourages international cooperation an aims to foster science by making information on Earth's environment more accessible.
As well as monitoring the composition of the air, ESA's missions also improve our understanding of atmospheric processes. In 2018, the agency launched Aeolus, a satellite that uses laser technology to monitor the winds that sweep across the planet.
The now inactive Aeolus mission carried an ultra-violet dopplar lidar. Once in orbit, the instrument would fire short pulses of UV light at the planet. These bounced off air molecules and other particles as they were blown through the atmosphere.
The fraction of light that scattered back towards the satellite was collected by a telescope. By measuring the shift in frequency of this light, Aeolus determined the speed and direction of the wind in the lower 30 km of the atmosphere.
Aeolus is one of many Earth Explorer missions designed to study the interactions between the planet's systems. The program was extended in May 2024 with a new mission called EarthCARE.
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