7.4.2 Traceability to World Radiometric Reference
Reference radiometers, which are calibrated annually by the World Radiation Centre in Davos, are used for the calibration of
radiometers manufactured by Kipp & Zonen. The reference radiometers are fully characterized, i.e. linearity, temperature
dependence and directional response are recorded.
Kipp & Zonen keeps two reference radiometers for each radiometer model. These reference radiometers are sent alternate years
to WRC for calibration, so production and calibration in Delft can carry on without interruption.
7.4.3 Recalibration
Radiometer sensitivity changes with time and with exposure to radiation. Periodic calibration every two years is advised.
Accurate calibrations can be done outdoors under clear sky conditions by comparison to a reference pyrgeometer of equal or
higher standard.
34
