MILAN — ESA’s EarthCARE satellite, launched in May 2024, has begun delivering promising results with its four advanced instruments, aimed at understanding how clouds and aerosols affect Earth’s energy balance. These initial findings were presented at the International Astronautical Congress (IAC) in Milan, Italy, and reveal the satellite’s potential to measure the complex interactions between clouds, aerosols, and thermal radiation.
The EarthCARE mission is a collaboration between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), dedicated to studying the balance between the energy Earth absorbs from the Sun and the thermal radiation it emits back into space.
This balance is crucial for maintaining Earth’s climate, as it is influenced by various factors, including clouds, aerosols, and greenhouse gases. While it is generally known that clouds and aerosols have a cooling effect on the atmosphere, their roles in heating and cooling processes are intricate and not yet fully understood.
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A synergistic approach
EarthCARE’s four instruments work in unison to measure different properties of clouds and aerosols. The instruments consist of a cloud profiling radar from JAXA, which captures the vertical structure and dynamics of clouds; an atmospheric lidar that provides profiles of aerosols and thin clouds, including cloud-top data; a multispectral imager offering a wide-field view across multiple wavelengths; and a broadband radiometer that measures the amount of solar and infrared radiation reflected and emitted by Earth.
According to Simonetta Cheli, ESA’s Director of Earth Observation Programmes, the mission’s early results are impressive, despite being in the satellite’s commissioning phase.
“Not only do they further confirm that all four instruments and the complex way the data are processed are functioning exceptionally well, but they also highlight the power of their combined measurements,” she said. The data, collected on September 18, provided insights from Central Europe to Sweden, with a focus on a thunderstorm near Milan.
The results highlighted a thunderstorm over northern Italy, which was part of Storm Boris and caused significant flooding in the Emilia Romagna region. This storm served as a case study for the satellite’s synergistic observational capabilities. The cloud profiling radar detected large particles in the thunderclouds, while the atmospheric lidar identified a 1–2 km thick ice layer at the cloud top. Together, these instruments delivered a detailed characterization of the storm’s vertical structure.
The measurements showed a strong cooling effect at the cloud top, where thermal radiation is emitted into space. Beneath this layer, however, the dense clouds trapped heat radiating from the Earth’s surface, causing a localized warming effect.
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Cirrus clouds’ dual role in warming and cooling
The data also captured cirrus clouds over Sweden, part of a high-altitude ice-cloud formation. These clouds are significant because they play a dual role in Earth’s climate: they allow sunlight to pass through and reach the surface, thereby warming it, while also trapping outgoing thermal radiation, thus contributing to atmospheric warming.
The atmospheric lidar provided information on almost the entire altitude range of the cirrus cloud, from 8 to 13 kilometers, whereas the radar mainly focused on the cloud’s lower regions where larger ice crystals were present.
In areas where the cirrus cloud thickened, the emission of thermal radiation into space led to localized cooling at the cloud top. Despite these localized effects, cirrus clouds contribute to an overall warming of the atmosphere.
Clouds and aerosols
The synergistic capabilities of EarthCARE’s instruments allow for comprehensive observations. The mission’s ability to simultaneously measure clouds and aerosols is unparalleled, providing crucial insights into how these elements interact with solar and thermal radiation.
According to Thorsten Fehr, ESA’s EarthCARE Mission Scientist, “Having the data available at this early stage is a testament to the outstanding work of the EarthCARE team, particularly the scientists who developed these data products.”
JAXA’s contributions have also been significant, as noted by Hitonori Maejima, Senior Chief Officer on Earth Observation Missions at JAXA. “By combining measurements from its four sensors, EarthCARE can capture different types of cloud, aerosols, and their function,” he said, underscoring the importance of international collaboration between ESA and JAXA.
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Implications for climate science
The initial results from EarthCARE will ultimately help improve climate models, contributing to a better understanding of how clouds and aerosols influence Earth’s climate. The data reveal both localized cooling effects, such as those observed at the tops of thunderstorms and cirrus clouds, and broader warming trends, highlighting the complex interactions within the atmosphere.
Other features observed in the data included a low-level aerosol layer, likely caused by pollution-related haze over Germany, and a low-altitude marine cloud over the Baltic Sea. These findings further illustrate EarthCARE’s capability to detect a wide range of atmospheric phenomena, that in the coming years will enhance our understanding of their roles in climate regulation.
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