At the start of November 2004 the new equipment was installed at Cabauw tower. Details can be found on this website in the news section. The CO2 measurements are now performed by a Licor 7000 monitor, stabilized at 30 (+/- 0.1) °C and 1 µbar pressure difference between cell A and B. The other greenhouse gases (CH4, N2O and SF6) and additionally CO are measured using a Agilent 6890N Gas Chromatograph.
Calibration is performed daily at 1:00 UTC using four secondary standards produced by MPI Jena, these are linked directly to NOAA CMDL primary standards. Vertical concentration gradients of all gases are measured every half hour. One measurement takes five minutes. We measure at 4 heights above ground level: 200, 120, 60 and 20m. Every half hour also the concentrations of two target cylinders are measured in order to detect drift of the sensors. The data is transferred on a hourly basis to Petten through an internet link. In the following pictures you can see the measured concentration gradients of all components of the last 24 hours and last week respectively. Be aware that this data has been calibrated using an automated routine without human intervention so is not guaranteed to be accurate.