Features

Rural, grass and peat land
213 m tower, remote sensing, in situ sensor networks

Vertical profiling of aerosols, clouds, humidity, temperature, wind
Total column measurement of aerosols, liquid water, water vapour, trace gases
Soil moisture, energy fluxes, turbulence
Greenhouse gases
Precursor trace gases, aerosols, condensation nuclei
Clouds, rainfall, radiation

Background

The Cabauw station is located in the western part of The Netherlands (51.971° N, 4.927° E) in a polder 0.7 m below average sea level. At the site, a large set of instruments is operated to study the atmosphere and its interaction with the land surface. The Cabauw site is used for:
– Monitoring of long-term tendencies in atmospheric conditions and composition;
– Studies of atmospheric and land surface processes for climate modelling;
– Validation of space-borne observations and atmospheric models;
– The development and implementation of new measurement techniques.

The 213 meter high mast at the Cabauw site was built for meteorological research, specifically to establish relations between the state of the atmospheric boundary layer, land surface conditions and the general weather situation for all seasons. The nearby region is agricultural, and surface elevation changes are at most a few metres over 20 km. Within 40 km radius there are four major synoptic weather stations, among which is the regular radiosonde station at De Bilt, ensuring a permanent supporting mesoscale network. To ensure undisturbed measurements at low levels, auxiliary 20m masts are installed. On site are also well-kept observation fields for micrometeorological observations, including soil heat flux, soil temperatures and various radiation measurements (including a BSRN station). Remote sensing observations, of e.g. clouds, aerosols, moisture and temperature, are performed at the Remote Sensing Site located 300m SSE of the main tower, using a suite of active and passive remote sensors. A scanning X-band radar is operated on the top of the tower. Greenhouse gas concentrations, including a gradually increasing number of additional tracers, have been measured since 1995.

 

Rationale for including in the Ruisdael Observatory

The observation program performed at the site provides a unique set of observations bringing the characterization of the atmosphere at Cabauw to a level that is matched by only a very few station world-wide.

  • In the Ruisdael observatory, Cabauw will fulfil the role of main station, where the largest and most complete set of observations is collected;
  • The Cabauw dataset will be routinely used to initialize and verify the model runs performed by the computational models run for the Ruisdael Observatory;
  • Observing cloud-aerosol interactions over the central part of The Netherlands, under influence of varying air masses. A combination of cloud, aerosol microphysics and chemistry measurements enables a detailed long-term aerosol-cloud interaction study and comparison with satellite measurements;
  • Observing the regional evolution of aerosol;
  • Observing and quantifying the Dutch anthropogenic greenhouse gas fluxes;
  • Observing 3D time-resolved distributions of key atmospheric parameters.

 

Added functionality in Ruisdael

For the Ruisdael Observatory, the integrated observation strategy of the measurement program will be enhanced from the ‘soda straw’ view to a 3D cylinder for key parameters by including scanning radars and lidars as well as regional networks. These parameters will include radiation, aerosols, clouds and trace constituents, in a radius of 30 km around the site. In addition, the existing Cabauw greenhouse gas profile measurements (CO2, CH4, N2O,CO) will be brought to ICOS level 1 standard. The measurement will be extended with NO2/NO/O3/NH3 profiles to make the link between the gas and aerosol themes. The chemical speciation of the aerosols will both allow for air mass foot printing and aerosol chemical process studies and cloud formation studies. The optical instrumentation will provide the input for the aerosol physics.

Coordinator of the Cabauw site is consortium partner KNMI.

Contact-details: Arnoud Apituley

www.cesar-observatory.nl

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