Fuelling Earth’s climate system

The climate system is fuelled by incoming radiation and cooled by long-wave thermal radiation emitted back into space. As solar radiation reaches Earth, some is reflected back into space by the surface, clouds as aerosols.

Solar radiation not reflected or ‘scattered back’ to space is converted to heat and emitted by Earth as thermal radiation. Gases such as water vapour, carbon dioxide and methane along with clouds and aerosols trap some of this outgoing radiation – in what is commonly described as the ‘greenhouse effect’, heating the atmosphere.

Aerosols also play a central role in the life cycle of clouds by acting as condensation nuclei – thereby having an indirect effect on radiation through their influence on cloud formation.

Owing to their high variability in time and space and their physical properties, clouds and aerosols are particularly difficult to represent quantitatively in numerical models.

Vertical structures of clouds vary from barely visible thin layers to massive cumulonimbus towers that stretch through the troposphere and, in the tropics, penetrate the tropopause.

Because of the lack of appropriate global datasets, information on cloud formation, aerosol-cloud interaction and cloud radiative properties are the largest source of uncertainty in today’s climate models.

In response to these needs, the objective of the EarthCARE mission is to improve the understanding of the interactions of clouds, aerosols and radiation on a global scale. This will be achieved with globally collocated datasets of vertical cloud and aerosol profiles along with radiative heating profiles and radiative flux observations at the top of the atmosphere.

Data from EarthCARE will mean that these variables can be included correctly and reliably in climate and numerical weather prediction models.