ACTRIS, the European Research Infrastructure Consortium (ERIC) for Aersols, Clouds and Trace Gases forms the largest multi-site infrastructure for atmospheric research in the world, involving more than 100 institutions across Europe.

ACTRIS provides data on the short-lived components of the atmosphere from the ground to the stratosphere and thus helps to reduce the uncertainties in the prediction of future climate. The short-lived climate drivers are usually only in the atmosphere for a few hours to weeks - in contrast to the long-lived greenhouse gases such as carbon dioxide or methane, which remain in the atmosphere for many years to decades. For example, water vapor, aerosols and clouds are highly variable components of the atmosphere, but have a major impact on climate. And they are changing in our warming world. 

The Institute of Geophysics and Meteorology at the University of Cologne has been operating the cloud observation platform JOYCE (Jülich Observatory for Cloud Evolution) in cooperation with Forschungszentrum Jülich for more than ten years. JOYCE is located on a roof platform of the Insitut for Climate and Energy Research (ICE3) at Forschungszentrum Jülich. JOYCE is an ACTRIS National Facility and additionally hosts a the Topical Center Unit for MicroWave Radiometers (MWR) within the ACTRIS Center for Cloud Remote Sensing (CCRES). 

While typically satellites deliver two-dimensional cloud observations, the JOYCE instrumentation can continuously  measure the vertical structure of clouds, i.e. their interior concerning water content, phase discrimination, particle size or even number concentration. This is only possible through a combination of different ground-based remote sensing instruments, which can - in addition to the environmental vertical observations of temperature, humidity, winds and turbulence - enhance our knowledge how clouds form, develop and decay; knowledge that is essential for representing clouds correctly in weather and climate models.

ACTRIS Reference

Laj et al. (incl. B. Pospichal): Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS): The European Research Infrastructure Supporting Atmospheric Science, Bulletin of the American Meteorological Society , 2024. https://doi.org/10.1175/BAMS-D-23-0064.1