Cloud Research at Sonnblick Observatory (SBO) in the frame of ACTRIS

At the Sonnblick Observatory SBO of the Central Institute for Meteorology and Geodynamics (ZAMG), an international measurement campaign to study clouds is running until 2 December. 24 measuring instruments, supervised by 38 scientists from nine nations, are investigating the formation of clouds. In addition, the European Centre for ambient Cloud Intercomparison Measurements is established at the SBO at an altitude of 3,16 metres above sea level, according to a press release.

The centre is to provide high-quality measurements for research and predictions in the cloud area. For it is still not fully understood how clouds are formed and which chemical and physical processes take place in them that lead to rain or snowfall. However, these processes are important factors in the calculation of weather forecasts for the next few days and the creation of climate scenarios for the next few decades. In order to intensively research the properties of clouds, ACTRIS, a new European infrastructure for the observation and analysis of aerosols, clouds and trace gases, is currently being built. In the future, it will also take a leading position worldwide.

High-quality measurements

"The Sonnblick Observatory plays a central role in ACTRIS," said the head of the observatory, Elke Ludewig, from ZAMG. "We are setting up the European Centre for Cloud Intercomparison Measurements here, called ECCINT - European Centre for cloud ambient intercomparison. Within the framework of ACTRIS, we are responsible, among other things, for the standardisation of cloud measurements in Europe, the calibration of highly sensitive measuring instruments and data management, and together with around 30 fixed measuring sites of European research institutions as well as mobile platforms such as aircraft and ships, we will provide high-quality measurements for research and forecasts in the cloud domain."

A first international pilot measurement campaign to record cloud properties is currently underway at the Sonnblick Observatory. Such campaigns are to take place every two years in the future. "The current measurement campaign, which runs from 21 November to 2 December, involves 38 researchers from nine countries," says Ludewig. "They are using 24 special measuring instruments to determine a wide variety of cloud parameters, such as the liquid water content, the size and composition of the droplets and ice crystals, and the chemical composition of the cloud water."

Logistical and technical challenge

The measurement campaign is a logistical and technical challenge. Twenty external measuring instruments from the campaign partners, some of them new prototypes, have been installed on the observatory's measuring terraces. Within two weeks, the instruments will be exposed to different weather conditions and the data will be analysed. Two intensive weeks for the science and also for the ECCINT operator Christian Maier, who is responsible for the technical implementation of the campaign: "The transport, power supply, network connections, data transmission, mounts, numerous connections and many small things were planned and prepared individually for the individual instruments for weeks. In sun, wind, snow, cold and even at night, all instruments could be installed within two days. Now we are excited about the instrument performance and the data!"

Organisations from Austria, the Czech Republic, Finland, France, Germany, Greece, the Netherlands, Switzerland and Sweden are involved in the measurement campaign. The aim is to build up a high-quality data set in the long term, which will be available worldwide for research into clouds and will also help to further improve weather forecasts and climate models. Clouds play a special role in weather and climate models because, depending on their size, type and occurrence, they cause the atmosphere to warm up or cool down. There are numerous interactions here that have not yet been completely clarified.