CESAR Observatory

The Cesar Observatory is located in the western part of the Netherlands (51.971° N, 4.927° E) in a polder 0.7 m below mean sealevel. At the site a large set of instruments is operated to study the atmosphere and its interaction with the land surface.

The Cesar site is used for:

  • Monitoring of long term tendencies in atmospheric changes
  • Studies of atmospheric and land surface processes for climate modeling
  • Validation of space-borne observations
  • The development and implementation of new measurement techniques
  • Training of young scientists at post-doc, PhD and master level.

Three universities and five major research institutes collaborate in Cesar. It is the focal point of experimental atmospheric research in The Netherlands.

If you have any questions about this website or request for additional pages, please contact Henk Klein Baltink at KNMI (henk.klein.baltink@knmi.nl). Also if you are a member of CESAR and don't have the username/password for the member section, please contact Henk Klein Baltink.

A link to the CESAR database portal is listed in the menu on the right hand side.


2016-AUG-08: CINDI-2 Campaign 2016

In September 2016, the CINDI-2 campaign will be held in Cabauw. CINDI-2 (Cabauw Intercomparison Campaign of Nitrogen Dioxide measuringInstruments) is a preparatory campaign for the validation of Sentinel-5p/TROPOMI that is scheduled for launch by late 2016. During CINDI-2, additional experiments will also be carried out for the ACTRIS-2 project for light absorption of aerosols and turbulent transport of aerosols. Campaign information is posted on CINDI-2 and the ACTRIS website.

2016-AUG-08: CESAR on National Landscape of Large Research Facilities

CESAR is listed on the Dutch National Landscape of Large Research Facilities of the Netherlands Organisation for Scientific Research (NWO). Click here for the NWO page about CESAR.

2016-FEB-01: CESAR now a certified GRUAN station

GRUAN, the GCOS Reference Upper Air Network (www.gruan.org), is an international reference observing network, designed to fill an important gap in the current global observing system. GRUAN measurements will provide long-term, high-quality climate data records from the surface, through the troposphere, and into the stratosphere. These will be used to determine trends, constrain and calibrate data from more spatially comprehensive observing systems (including satellites and current radiosonde networks), and provide appropriate data for studying atmospheric processes. GRUAN is envisaged as a global network of eventually 30-40 sites that, to the extent possible, builds on existing observational networks and capabilities.

Cabauw is a distributed GRUAN site, together with De Bilt. The radiosondes launched from De Bilt are the first certified data stream to GRUAN. Data streams under development are the ozone sonde, GNSS water vapour columns, Microwave water vapour columns and Raman lidar water vapour profiles. Cabauw/De Bilt is actively involved in the development of these reference quality data products.

2015-JUL-28: TNA ACTRIS-2 now open

The ACTRIS-2 call for Transnational Access (TNA) is now open!

ACTRIS-2 (Aerosols, Clouds, and Trace gases Research InfraStructure) is a European H2020 Project aiming at integrating European ground-based stations for long-term observations of aerosols, clouds, and short-lived gas-phase species. ACTRIS aims to construct a user-oriented research infrastructure in Europe.

ACTRIS-2 provides hands-on access for researchers to CESAR and other world-class observing platforms in Europe. Limited financial support is available to contribute to the travel and subsistence costs of the users. For more information and to apply, please visit the ACTRIS-2 website (click here)

2014-OCT-07: ACCEPT Campaign

During October and the first half of November 2014 the TROPOS institute executes the ACCEPT campaign in collaboration with TU-Delft and KNMI. ACCEPT is performed with support for Trans National Access (TNA) from the ACTRIS project. Click here to visit the ACCEPT weblog.

2014-JUN-02: CESAR flyers

Both an English and Dutch version of the CESAR flyer have been published (click on "other" under "Publications" in menu to download).

2014-JAN-15: Report on 40 year Cabauw research

An overview of research conducted at the Cabauw site in the past 40 years has been published as a KNMI report (click on "reports" under "Publications" in menu to download).

2013-SEP-19: CESAR Science Day 2013

On 19th of June 2013 a CESAR Science Day was organised at KNMI. The presentations and posters have been posted on the website now (click on link in menu section Consortium).

2012-OCT-26: Symposium 40 years Cabauw

In october 1972 the Cabauw mast was officially opened after a few years of preparation and building. For more information click on the link in the menu on the right.

2012-MAY-21: PEGASOS Campaign

In the second half of May 2012 CESAR Observatory is the main focus of the PEGASOS Campaign. Click here to visit the project website.

the 213 m. high meteorological tower

General information

Cabauw 40 year



CESAR Consortium

CESAR Database