CESAR ObservatoryCabauw Experimental Site for Atmospheric Research

Contact details:

Arnoud Apituley
KNMI, Utrechtseweg 297, 3731GA De Bilt

CESAR Observatory is a leading atmospheric observatory in the world. The observatory is one of the few that can characterize the atmosphere from the ground up to the top of the atmosphere, by combining in situ sensors on the ground, along a 213 meter measurement tower, and ground-based remote sensing to reach higher altitudes for measuring wind, turbulence, aerosols, trace gases and clouds and radiation. The observatory provides essential state-of-the-art data to understand atmospheric processes, validate satellite observations, and detect long-term trends. The freely available data are used to improve climate, weather and air quality models. The station is a focal point of experimental atmospheric research in The Netherlands, and a core station in the global network of observatories

CESAR Observatory is a leading atmospheric observatory in the world. The observatory is one of the few that can characterize the atmosphere from the ground up to the top of the atmosphere, by combining in situ sensors on the ground, along a 213 meter measurement tower, and ground-based remote sensing to reach higher altitudes for measuring wind, turbulence, aerosols, trace gases and clouds and radiation. The station is a focal point of experimental atmospheric research in The Netherlands, and a core station in the global network of observatories. The observatory provides essential state-of-the-art data to understand atmospheric processes, validate satellite observations, and detect long-term trends. The, freely available, data are used to improve climate, weather and air quality models. Furthermore, the observatory provides data to develop underpinning scientific knowledge for topics like extreme weather events, water management, visibility conditions for road and air traffic, air pollution and volcanic ash episodes, wind climatology and the radiation balance. This knowledge serves policy makers in various ministerial departments as well as economic activities.
The 213 m high mast was specifically built in 1972 for meteorological research to establish relations between the state of the atmospheric boundary layer, land surface conditions and the general weather situation for all seasons. On site are well-kept observation fields for micrometeorological observations, including soil heat flux, soil temperatures and various radiation measurements. Detailed observations, of e.g. clouds, aerosols, moisture and temperature, are performed with (remote) sensors near the main tower. A scanning rain radar is operated on the top of the tower. A full list of instruments presently located in Cabauw is available online (http://www.cesar-observatory.nl).
CESAR is used for:
- Monitoring of long term tendencies in atmospheric changes,
- Studies of atmospheric and land surface processes,
- Validation of satellite observations,
- The development of new measurement techniques,
- Training of young scientists.
Three universities and five major research institutes collaborate in Cesar. The facility has a strong integrating effect on atmospheric and environmental science in The Netherlands: the multi-disciplinary character of the science of clouds and precipitation stimulates cooperation, and provides fertile grounds for joint observations and campaigns that lead to better understanding of atmospheric processes by confronting models to those data: numerous model studies are performed with CESAR observations.
CESAR has compiled a long-term dataset of advanced parameters. International research groups aiming at targeted measurement campaigns are attracted by the complete set of observations continuously available at CESAR. The CESAR database is coupled to the database infrastructure of ACTRIS and embedded in EU-US cooperation programs to enable easy global dissemination.
The long-term European participation in the European ACTRIS infrastructure, now included in the ESFRI Roadmap 2016, ensures a strong international embedding of CESAR. The facility is one of the core stations in the ACTRIS infrastructure, and will host a radar calibration facility. Furthermore, itis one of the main tall towers for greenhouse gas observations in ICOS ERIC, and a main station for transnational access, instrument development and testing of the ACTRIS and InGOS research infrastructures.