03/12/2025
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True to its promise, the European Space Agency’s EarthCare satellite is now being used to directly calculate how clouds and aerosols affect Earth’s energy balance – the most important balance that controls our climate. In doing so, EarthCARE sets out to accelerate the accuracy of climate models, the same tools that guide global climate policy and action.
Although clouds and aerosols are currently known to have an overall cooling effect, their interactions with energy coming from the Sun and thermal radiation emitted back into space by the Earth are highly complex, and not fully understood.
As the planet warms from greenhouse gas emissions, it’s unclear how clouds will respond. For example, a decrease in cloud cover will allow more sunlight to reach the surface, increasing temperatures.
earth radiation budget
Aerosols add another layer of uncertainty. They cool the climate by reflecting sunlight and making clouds more reflective and long-lived. But recent changes – from sharp declines in industrial pollution to huge plumes of wildfire smoke – could significantly alter their key role in the climate system. However, the full impact of these changes is unclear.
Predictions of future climate change depend on computer models that simulate the atmosphere, oceans, and the broader Earth system under different scenarios. Climate model representations of clouds, aerosols, and their interactions with sunlight and infrared radiation are based on simplified mathematical descriptions of their behavior, often dependent on measurements and many assumptions.
EarthCARE on Hurricane
Launching in May 2024, EarthCARE – an ESA Earth Explorer mission developed in partnership with the Japan Aerospace Exploration Agency (JAXA) – carries four specialized instruments designed to simultaneously take various measurements of clouds and aerosols.
This synergy is important: by combining these observations, EarthCARE can work out important cloud properties such as how much water they contain and the size of cloud particles. In turn, this can be used to improve how these aspects are represented in climate models, leading to more reliable climate projections.
The animation below presents a sequence of measurements obtained by EarthCare on Typhoon Ragasa near the Philippines on 20 September 2025, and shows one of the mission’s key science goals – ‘radiative closure’.
EarthCARE tools work in synergy to improve climate models
The animation first shows how data from EarthCARE’s Cloud Profiling Radar (CPR), Atmospheric Lidar (ATLID) and Multispectral Imager (MSI) are combined to obtain vertical slices of properties such as cloud and precipitation water content – that is, water in liquid droplets, ice crystals, rain and snow.
Next, information from MSI’s horizontal imagery is used to extrapolate these vertical cloud profiles onto the satellite’s track. By identifying pixels with similar optical properties, the system reconstructs the 3D cloud structure.
Using a computational technique known as radiative transfer modeling, this 3D cloud representation is used to estimate how incoming sunlight is scattered by cloud particles and the Earth’s surface, and how much is consequently reflected back into space.
In the animation, this calculated reflected sunlight appears as a blue shaded horizontal bar and a red line at the top. This is then compared to independent measurements by EarthCARE’s Broadband Radiometer (BBR), shown by the yellow line at the top, and the agreement is very good.
Robin Hogan, Principal Scientist at the European Center for Medium-Range Weather Forecasts (ECMWF), said: “We always expected EarthCare to deliver on its promises, and these results certainly show that it is doing just that.
EarthCARE improves estimates of the impact of clouds on Earth’s energy balance
“Here we see that EarthCARE is able to work out the detailed properties of clouds and aerosols in the atmosphere, and then immediately check that their predicted radiative effects are consistent with solar and infrared energy fluxes that are also measured by the satellite. This onboard validation of EarthCARE’s data gives additional confidence in the use of cloud and aerosol properties to test and improve climate models.”
As an ESA Earth Explorer, EarthCare is a research mission, but its data are so reliable that they will also be used in daily weather forecasts.
Professor Hogan explained, “At ECMWF we want to integrate EarthCare data into our models in real time: by providing a more accurate picture of cloud locations at the start of the forecast, these data will help models to better capture the evolution of weather systems and give more reliable predictions.
“Work on integrating EarthCare’s data streams is progressing rapidly, and the system is on track to be operational very soon. EarthCare is therefore not only advancing our understanding of our climate, but also providing immediate benefits for day-to-day forecasting and climate services.”
ESA’s EarthCare Mission Manager, Björn Fromknecht, said, “On 1 December, during the second joint workshop bringing together European, Canadian and Japanese scientists, the full suite of EarthCare Level-2 data products was released to the public for the first time. This follows the release of some Level-1 data in January and Level-2 data in March.
“This new release includes the much-anticipated ‘Radiative Closure’ product, which links measurements of clouds and aerosols directly to observed energy fluxes – providing an unprecedented window into the processes that shape Earth’s climate.”
Making the full dataset openly available means researchers around the world can now begin to test new hypotheses, validate climate and weather models, and explore how recent atmospheric changes – from wildfire smoke to changes in pollution – are affecting the planet’s energy balance. It also strengthens international collaboration: by sharing tools and expertise across agencies and continents, the EarthCare community is accelerating scientific progress and expanding the reach of the mission.
Data are available from the EarthCARE online dissemination service.
Also read news from JAXA: All observational data now publicly available.
