The Cabauw In-situ Observational Program 2000 - Present: Instruments, Calibrations and Set-up

The Cabauw observational program on land surface-atmosphere interaction aims at monitoring the physical aspects of the atmospheric boundary layer and the underlying surface. The program covers both the measurement of state variables (structure) and fluxes (processes). The measurements of the underlying surface (vegetation and soil) are limited to those aspects that have a significant influence on the state of the atmospheric boundary layer. The datasets derived from this program have been used, among others for: process studies, evaluation of land surface and turbulence schemes in atmospheric models, climate studies, and the validation of satellite retrieval schemes. The observational program has been setup along general physical principles to facilitate a broad range of possible applications. These principles are the surface budgets of radiation, heat, water and momentum. Observed are the profiles of wind speed and wind direction, temperature, humidity and visibility along the 200 m Cabauw meteorological mast, the surface flux of precipitation, the surface radiation budget consisting of the four components short wave up- and downward radiation and long wave up- and downward radiation, the components of the surface energy budget, sensible heat flux, latent heat flux and soil heat flux, the momentum flux and auxiliary parameters to judge the state of the land surface like soil water content and radiative vegetation temperature. As a by-product the surface flux of carbon-dioxide is also measured.

This report is one in a series of 4 information sources. It gives a comprehensive description of relevant aspects of the observations enabling the user to judge the quality of the observations, and whether the observations are suitable for the intended user. Described are the instruments, their calibration and setup of the instruments in the field, data logging and data processing, quality checks and dissemination into datasets. Further relevant aspects of the location and the surroundings of the measurement site at Cabauw and the changes over time are described in so far it is needed to interpret the observations.