The much-awaited EarthCARE satellite successfully embarked on its journey into space on 29 May 2024, at 00:20 CEST, aboard a Falcon 9 rocket from the Vandenberg Space Force Base in California, USA—anticipation of the new data is causing excitement in the remote sensing community.

Carefully designed to revolutionise our understanding of how clouds and aerosols affect our climate, while the climate crisis firmly takes hold, the Earth Cloud Aerosol and Radiation Explorer, known as EarthCARE, will soon be providing crucial data to illustrate the complex interactions between clouds, aerosols and radiation within Earth’s atmosphere.

A joint venture between ESA and the Japan Aerospace Exploration Agency, JAXA, it is the most complex of ESA’s research missions to date, with its set of four state-of-the-art instruments.

Unique to the mission is that these instruments will work together to provide a holistic view of complex interplay between clouds, aerosols and radiation, bringing new insight into Earth’s radiation balance, in relation to the climate crisis.

Just 10 minutes after its launch, the satellite separated from the rocket. Then, at 01:14 CEST, the Hartebeesthoek ground station in South Africa received the all-important signal indicating that EarthCARE is safely in orbit around Earth.

So what happens now?

The EarthCARE satellite is now being controlled from ESA’s European Space Operations Centre in Darmstadt, Germany. Controllers will spend the next few months carefully checking and calibrating the mission as part of the commissioning phase.

Launch and Early Orbit Phase (LEOP) has been successfully completed, now followed by a six month commissioning period, during which EarthCARE’s four instruments are gradually switched on, calibrated and their performances are verified.

During this period, data collections may be accessed by a restrained user group of the EarthCARE Commissioning Team, followed by members of the Calibration and Validation (Cal/Val) teams. Scientists are planning to validate EarthCARE data in global Cal/Val campaigns, where the data are compared to reference data from other satellite, airborne, shipborne and ground-based sensors.

Level-1 data public release is expected 6 months after launch, in early 2025, while Level-2 data public release is expected to start 3 months later, when first single and two sensor products, and then multi sensor synergistic products will be released to the public, following ESA’s free and open data policy.

But just why are scientists interested in EarthCARE data?

The state of our climate depends on a highly complex system involving intricate feedback loops and interactions between various components. It encompasses the processes that control the distribution of energy from the Sun across Earth's surface, and the subsequent redistribution of heat through various mechanisms. Understanding these interactions and mechanisms is essential for assessing the impact of humankind’s activity, predicting future climate trends and implementing effective strategies for climate mitigation and adaptation.

While scientists know that clouds and aerosols play extremely important roles in both cooling and warming our atmosphere, there remains uncertainty when it comes to accounting for the exact influence they have on Earth’s energy balance and, given the ongoing climate crisis, if they will exert an overall cooling or warming effect in the future.

EarthCARE’s suite of instruments will provide for the first time sufficient spatial resolution to see inside clouds and profile them, to help us understand how clouds and aerosols contribute to Earth’s radiation balance.

Whilst EarthCARE was under preparation, despite it being beyond the mission’s initial scope, forecasters at ECMWF were already investigating whether the satellite’s novel cloud data might contribute to weather prediction.

To do that, they had to check whether information such as radar and lidar data could be added to their global weather models. Using data from past missions, such as NASA’s CloudSat and the NASA/CNES CALIPSO satellite, they already started seeing improvements in prediction of temperature, wind, and precipitation.

Then Aeolus came along, carrying a very similar lidar instrument to EarthCARE’s. Aeolus’s wind data hugely boosted weather forecasts, and scientists have already been using its data to prepare the way for EarthCARE.

With EarthCARE, scientists can refine our atmospheric models and climate forecasts, giving us the tools to tackle the challenges of a changing climate with greater accuracy and precision.

What kind of data can we expect?

Science data acquired by the various EarthCARE instruments will be processed in ground segments in Europe and Japan, which will produce four Level-1 instrument data streams containing calibrated and geolocated instrument measurements, and a large number of geophysical data products (Level-2 products).

The data products cover, for example, target classifications, vertical profiles of microphysical properties of ice, mixed and liquid clouds, particle fall speed, precipitation parameters, and aerosol types.

EarthCARE Level-1 data products include two categories:

• Nominal products - contain calibrated instrument signals and are widely disseminated. They are fully calibrated, self-standing products

• Calibration products - used to optimise instrument settings, to monitor instrument performance, to update calibration coefficients as needed and contribute to the calibration of the nominal products. Calibration products are only disseminated to selected expert users

Calibrated Level-1b data from the Atmospheric Lidar, the Multispectral Imager and the Broadband Radiometer are produced by ESA, while Level-1b data from the Cloud Profiling Radar are produced by JAXA. Both ESA and JAXA produce and exchange EarthCARE Level-2 data products that include a comprehensive range of geophysical parameters related to aerosols, clouds, precipitation and radiation.