A major measurement campaign in Germany is aiming to improve the representation of clouds in weather and climate models by capturing their three-dimensional structure and impact on solar radiation.
The C3SAR (Cloud 3D Structure and Radiation) campaign, led by the German Research Foundation (DFG), is taking place from May to August 2026, southeast of Berlin. More than 40 researchers are deploying over 35 instruments at the German Meteorological Service’s (DWD) Lindenberg Meteorological Observatory and its Falkenberg measurement site.
The project focuses on quantifying how the spatial structure of clouds affects solar radiation at ground level – an area that has been difficult to model accurately. Current models struggle to represent the complex three-dimensional nature of clouds, limiting forecast precision.
As part of the campaign, researchers will measure radiation scattering in clouds while accounting for their full 3D structure. In addition to ground-based instruments, radiation measurements will be carried out using drones and helicopters, alongside comparisons with data from next-generation weather and climate satellites.
The Lindenberg site was selected due to its long-standing atmospheric research capabilities. The Richard Assmann Observatory has studied the atmosphere for more than 120 years and solar radiation for over 20 years. Its Lindenberg Column reference data set includes data from instruments such as cloud radars, ceilometers, microwave radiometers, Raman lidar, radiosondes and radiation sensors.
These systems are being supplemented by additional instruments from partner organizations. Among them is the AMUDIS in-situ instrument from Leibniz University Hannover, which measures radiation intensity from multiple directions across the sky with high spectral and temporal resolution.
The Leibniz Institute for Tropospheric Research (TROPOS), which leads the consortium, has also deployed its PyrNet network of 45 pyranometers across an area of almost 10 x 10km. The network measures solar irradiance, humidity and temperature, enabling spatial analysis of radiation variability caused by clouds.
Additional systems include the OCEANET measurement container, equipped with laser-based instruments to analyze polarized scattered radiation and derive cloud droplet size and concentration.
Cloud cameras from the University of Valladolid and the German Aerospace Center are being used to generate high-resolution ‘cloud masks,’ mapping cloud presence across the observation area.
The Falkenberg site is also serving as a base for aerial measurements. Drones operated by multiple research institutions, including the University of Tübingen, Technical University of Braunschweig and the Finnish Meteorological Institute, are being used to capture detailed cloud properties and solar radiation within and around cloud formations.
In related news, Copernicus launches Weather Replay app to explore historical weather data