With the initial images from each of the instruments aboard ESA's EarthCARE satellite now in hand, it's time to reveal how these four advanced sensors work in synergy to measure exactly how clouds and aerosols influence the heating and cooling of our atmosphere. Unveiled today at the International Astronautical Congress in Milan, Italy, these new results clearly highlight how EarthCARE's instruments can take different measurements of clouds and aerosols at the same time. These synergistic measurements promise to yield crucial insights into Earth's delicate energy balance. The energy balance accounts the amount of energy Earth receives from the Sun and the amount of thermal radiation it emits back out to space. Influenced by numerous factors, including clouds, aerosols and greenhouse gases, this balance is vital for regulating Earth's climate.

While it is known that clouds and aerosols generally help cool the atmosphere, their interactions with incoming and outgoing heat are highly complex and still not fully understood. Launched in May 2024, EarthCARE – a mission realised through a joint venture between ESA and the Japan Aerospace Exploration Agency (JAXA) – has the important task of measuring various aspects of our atmosphere to help us understand how clouds and aerosols reflect incoming solar energy back out to space and how they trap outgoing infrared energy.

ESA's Director of Earth Observation Programmes, Simonetta Cheli, stated, "Although we are still in the early stages of the mission and busy with the satellite's commissioning phase, the results we present today are truly remarkable. 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. This demonstrates that the mission is on track to achieve its objectives. The data, which were captured on 18 September, offer a sweeping view from Central Europe to Sweden. Notably, they reveal the many different signatures of a thunderstorm over northern Italy, near Milan where we are today."

Understanding EarthCARE's Instrumentation

EarthCARE integrates four sophisticated instruments that work together to provide a comprehensive view of atmospheric phenomena.

• The cloud profiling radar, provided by JAXA, analyzes the vertical structure and internal dynamics of clouds.

• The atmospheric lidar offers profiles of aerosols and thin clouds along with cloud-top information.

• The multispectral imager captures a wide-scene overview in multiple wavelengths.

• The broadband radiometer measures reflected solar radiation and the outgoing infrared radiation emanating from Earth.

These instruments operate synergistically, giving us a multifaceted understanding of our atmosphere. The animation accompanying this report delineates the capabilities of these instruments through two distinct features.

While the multispectral imager provides an overarching view of the scene, the animation first zeroes in on a recent thunderstorm event over northern Italy and northern Corsica. This storm was particularly devastating, contributing to severe flooding in Italy's Emilia Romagna region. The storm was linked to the larger convective system associated with Storm Boris, which also caused widespread damage throughout parts of Central Europe.

At the initial stage of the animation, the cloud profiling radar takes the lead, delivering substantial data due to the large particles forming within the thunderclouds. Subsequently, the atmospheric lidar ascertains a 1–2 km layer at the cloud's uppermost region, unveiling critical details about the ice layer that constitutes the cloud top. The synergy between the cloud profiling radar and lidar becomes particularly evident when focusing on the areas near the top of the clouds. In these regions, both instruments provide complementary data, enabling a more nuanced cloud characterization.

Insights Into Cloud and Aerosol Effects

Ultimately, EarthCARE's mission aims to elucidate the roles of clouds and aerosols in either warming or cooling the atmosphere. Initial results confirm this effectively. Significant findings indicate a strong cooling effect at the top of the thunderstorm. This cooling effect can be attributed to the heightened emission of thermal radiation into space. Beneath this cooling stratum, however, the dense cloud absorbs heat radiating from Earth's surface, thereby creating a distinctly warming effect.

Further analysis from the animation reveals cirrus clouds over Sweden, which belong to a high-altitude ice-cloud formation. These clouds are particularly important for climate science. They appear thin and permit sunlight to pass through, effectively warming the Earth's surface. However, they also trap thermal radiation emitted from the surface, thereby preventing it from escaping into space. This dual capacity illustrates their contribution toward overall atmospheric warming.

In contrast to the thunderstorm observations, atmospheric lidar delivers data over nearly the entire expanse of the cirrus cloud, between 8 and 13 km in altitude. The radar primarily concentrates on the lower regions, focusing on areas where larger ice crystals are generated. Despite this difference in focus, both the radar and lidar work in tandem within the lower two kilometers, facilitating synergistic retrievals over substantial portions of the cirrus cloud.

The overall heating impact of cirrus clouds, especially within their superior layers, emerges strikingly. Here, the clouds absorb solar radiation descending from above while simultaneously capturing thermal radiation emanating from the Earth's surface below. This warming mechanism is occasionally interrupted in regions where the cloud structure thickens—causing larger ice particles to form—that effectively obstruct thermal radiation from the Earth.

In these denser segments, the cloud top cools by emitting thermal radiation back into space. Despite localized cooling effects, cirrus clouds contribute more significantly to the overall warming of the atmosphere.

Additional Observations

EarthCARE's initial results showcase other noteworthy features, including a low-level aerosol layer likely linked to pollution-related haze over Germany, and a low-altitude marine cloud hovering over the southern Baltic Sea. Such observations underscore the mission's crucial role in observing and detailing various atmospheric conditions.

Thorsten Fehr, ESA's EarthCARE Mission Scientist, remarked, "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. This highlights EarthCARE's unique capability to simultaneously provide direct measurements of both clouds and aerosols, enabling an unprecedented assessment of their impact on climate."

Collaborative Efficiency and Data Processing

The success of EarthCARE can be attributed not only to its sophisticated instrumentation but also to the effective collaboration between ESA and JAXA. Hitonori Maejima, Senior Chief Officer on Earth Observation Missions at JAXA, stated, "By combining measurements from its four sensors, EarthCARE can capture different types of clouds, aerosols, and their function. This is a symbol of the collaboration between ESA and JAXA." This collaboration has allowed for a more comprehensive understanding of how different atmospheric elements interact with one another, leading to vital contributions to climate science.