It is required by the World Meteorological Organisation (WMO) that to provide data to the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) Brewers must be calibrated at least every two years.
Ozone calibration of Brewers MkII, MkIII and MKIV can be done at the Kipp & Zonen factory in Delft, from the beginning of April until the end of September, or at the customer’s site at dates depending on the solar zenith angle and the expected weather conditions at the location.
In both cases the Ozone calibration is by comparison to the Kipp & Zonen ‘travelling standard’ Brewer Mk III serial number 158, and UV calibration is by comparison both to this Brewer and to traceable calibrated reference UV lamps.
In order to calibrate a Brewer it must be in good operating condition, so recent data files will be required as well as some diagnostic tests. From this information Kipp & Zonen technicians can determine whether the Brewer is operating correctly and if any service work or parts might be needed.
Before calibration a full functional check and optimization of the Brewer will be carried out and consumables replaced as necessary. 2 to 3 days of good sky conditions are required for a reliable Ozone calibration.