A look inside the clouds: measurement campaign aims to improve the accuracy of climate models
Leipzig,
12.05.2026
Extensive measurement campaign in Brandenburg investigates the influence of spatial cloud structure on radiation, weather and climate
Leipzig/Lindenberg. To improve weather and climate forecasts, clouds must be described more accurately in the relevant models. One problem is that, until now, it has not been possible to represent clouds in their complex three-dimensional structure. The C3SAR group of the German Research Foundation (DFG) aims to change this and, for the first time, determine the scattering of solar radiation in clouds whilst taking their three-dimensional structure into account. The C3SAR measurement campaign (Cloud 3D Structure and Radiation) is a key component of this effort. It will take place from May to August 2026 south-east of Berlin. Over 40 researchers will operate more than 35 instruments at the Lindenberg Meteorological Observatory of the German Weather Service (DWD) and its measurement site in Falkenberg (Tauche). The aim is to measure the influence of the three-dimensional nature of clouds on solar radiation at ground level with unprecedented accuracy. In addition to ground-based measurements, radiation measurements using drones and helicopters will be carried out in parallel for the first time, alongside comparisons with data from the latest generation of weather and climate satellites.
The fact that this extensive measurement campaign is taking place in Brandenburg is due to the expertise of the Lindenberg Meteorological Observatory: the Richard Aßmann Observatory brings together the DWD’s research into the physical structure of the atmosphere, from the ground up to the stratosphere. The atmosphere has been studied here for more than 120 years, and solar radiation for over 30 years. The observatory offers a wide range of routine ground-based measurements. These include cloud radars, ceilometers, microwave radiometers, a Raman lidar, radiosondes, an infrared hemispheric sky imager, short- and long-wave radiometers, and cloud cameras. These extensive measurements are also known as the ‘Lindenberg Column’.
These devices are supplemented by instruments from partner institutions. These include the innovative in-situ instrument AMUDIS from Leibniz University Hannover. This instrument enables the simultaneous measurement of radiation intensities from many directions with high spectral and temporal resolution. The measurements are taken simultaneously across the entire sky above the measurement site and thus provide an important counterpart to the vertical point measurements of the other instruments.
The Leibniz Institute for Tropospheric Research (TROPOS) acts as the consortium leader and, in April, set up its PyrNet measurement network comprising 45 pyranometers, which were last used three years ago during a campaign in the Midwestern United States. The small devices are placed on poles in the countryside and measure the downward solar radiation flux density as well as humidity and temperature. The network will be most densely concentrated at the observatory in Lindenberg and on the measurement field in Falkenberg, but will extend over an area of almost 10 by 10 kilometres. This network of sensors across the area is essential for spatially mapping the fluctuations in solar radiation caused by clouds. In addition, the OCEANET measurement container from TROPOS, which has already been used in the Arctic and Antarctic, is being deployed. Of particular importance here is a laser measuring device that measures the polarised scattered radiation from clouds at two angles of incidence. This allows, for example, the size and number of cloud droplets to be measured in the lower part of the cloud. By August, the DWD measuring station in Falkenberg will thus be equipped with active and passive remote sensing instruments of a cloud and radiation station, including a cloud radar, a microwave radiometer, a ceilometer, a Doppler wind lidar and a sun photometer, a broadband radiation station and other measuring instruments provided by/from the Leipzig Institute for Meteorology (LIM) of Leipzig University.
In addition, there will be cloud cameras from the University of Valladolid and the German Aerospace Centre (DLR). Observations from several cameras will be combined to create so-called ‘cloud masks’. These provide high-resolution information on where clouds were and where they were not at the time of the measurements.
In addition, the Falkenberg site will serve as a base for various aerial measurements: drones will be deployed in both May and July. These will be operated by the University of Tübingen, the Technical University of Braunschweig and the Finnish Meteorological Institute (FMI). On the one hand, the drones enable precise measurements of cloud properties and, above all, variations within the cloud. Secondly, additional drones will record solar radiation beneath the clouds. By repeatedly flying fixed flight patterns, these measurements provide a valuable counterpart to the measurements from the ground-based pyranometer network. TROPOS contributes what are likely to be the most spectacular measurements with ACTOS. The ‘Airborne Cloud Turbulence Observation System’ is a measurement platform suspended from a helicopter by a 150-metre-long cable. During the almost daily flights, ACTOS is pulled through the clouds and measures properties such as droplet number and size distribution – parameters that determine the radiative effect of clouds. The helicopter flights will take off from Falkenberg between 6 and 24 July. At this time of year, convective cumulus clouds usually predominate. Towards the end of the campaign, however, the likelihood of stratus clouds associated with low-pressure systems increases, offering the opportunity to include such cloud scenarios as well and obtain as comprehensive a picture of clouds as possible.
The high-tech instruments on the ground and in the air are further supported by a new generation of modern satellite measurements. Both the METEOSAT Third Generation (MTG) satellites and the EarthCARE satellite, launched in 2024, offer unprecedented opportunities for observing cloud development and measuring three-dimensional cloud fields and their corresponding radiative effects. This combination will compile a unique dataset on cloud properties, radiation intensity and radiation flux at the ground and at the upper boundary of the atmosphere. This dataset will form an important basis both for the work of the C3SAR research group and for future research projects in the field of clouds and climate. “The combination of remote sensing, in-situ measurements and modelling will provide a realistic correlation between cloud properties and their radiative effects, which will be extended to multiple sites in Europe, Africa and the polar regions in the planned second phase of C3SAR, with the ultimate aim of achieving a global understanding of spatial cloud structure within the climate system,” adds Prof. Andreas Macke from TROPOS and spokesperson for the DFG research group C3SAR.
The researchers also intend to use the wide range of equipment and extensive measurements to support the next generation of scientists: from 6 to 12 July, the C3SAR research group will be holding a summer school in Lindenberg. Over a dozen internationally renowned scientists will be delivering a variety of lectures to 30 students and young researchers. Participants will be introduced to the campaign both through working with data from the campaign and by assisting with the measurements. The aim is to spark an interest in this important topic among the next generation of scientists. Tilo Arnhold
Contacts:
Dr Jörg Schmidt,
Coordinator of the DFG Research Group “C3SAR – Cloud 3D Structure and Radiation”,
Department of Remote Sensing of Atmospheric Processes, Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, and University of Leipzig, Germany
Tel. +49 341 2717-7497
https://c3sar.de/contact/
and
Prof. Dr Andreas Macke,
Spokesperson for the DFG Research Group “C3SAR – Cloud 3D Structure and Radiation”,
Director and Head of the Department of Remote Sensing of Atmospheric Processes, Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, and University of Leipzig, Germany
Tel. +49 341 2717-7060
https://www.tropos.de/institut/ueber-uns/mitarbeitende/andreas-macke
and
Dr Christine Knist
Co-leader of the ground-based measurements for the DFG research group “C3SAR – Cloud 3D Structure and Radiation”,
Lindenberg Meteorological Observatory, German Weather Service
Tel. +49 69 8062 5749
and
Dr Stefan Wacker
Co-lead of campaigns in the DFG research group “C3SAR – Cloud 3D Structure and Radiation”,
Head of the Radiation Processes Section at the Lindenberg Meteorological Observatory of the German Weather Service
Tel. +49 69 8062-5860
or
Tilo Arnhold
Public Relations, TROPOS
Tel. +49 341 2717-7189
http://www.tropos.de/aktuelles/pressemitteilungen/
and
Alina-Louise Kramer
Press and Public Relations, DWD
Tel.: +49 (0) 69 8062 4505
https://www.dwd.de/DE/service/kontakt/presse/presse_node.html
Photos:
https://owncloud.gwdg.de/index.php/s/t6xQgEuY1dilOJ4
Links:
C3SAR Campaign: https://c3sar.de/campaign/
Research Unit C3SAR: https://c3sar.de/
DFG Research Group “C3SAR – Cloud 3D Structure and Radiation”: https://www.tropos.de/institut/abteilungen/fernerkundung-atmosphaerischer-prozesse/clouds-aerosols-and-radiation/c3sar
The Lindenberg Meteorological Observatory – Richard Aßmann Observatory (MOL-RAO) of the DWD: https://www.dwd.de/DE/derdwd/standorte/observatorien/mol/mol.html
Advanced MUltiDIrectional Spectralradiometer (AMUDIS) at the University of Hanover: https://www.meteo.uni-hannover.de/institut/ausstattung/messgeraete/mudis
PyrNet pyranometer network: https://www.tropos.de/forschung/grossprojekte-infrastruktur-technologie/technologie-am-tropos/pyranometer-netzwerk
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