The CGR 4 differs from all other Pyrgeometers in that it allows accurate daytime measurements on sunny days without the need for a shading device. Due to the unique construction of the CGR 4, solar radiation of up to 1000 W/m² induces window heating of less than 4 W/m² in the overall calculated downward radiation. In the Baseline Surface Radiation Network (BSRN) manual (WMO/TD-No.897) an extended formula is described. This formula corrects for window heating and so called “solar radiation leakage”. Due to the very low window heating offset and optimal spectral cut-on wavelength, these corrections are not necessaire for the CGR 4.
We advise to re-calibrate the Pyrgeometer every two years.
More information about our calibration service can be found here.
If the CVF 3 is used for a Pyrgeometer the effect of sunrise is not valid and continuous 5 Watt is preferred. In extreme cold climates , polar / mountain tops, the 10 Watt heater can be used continuously.
Kipp & Zonen B.V.
Delft - The Netherlands
T: +31 15 2755 210
Kipp & Zonen France S.A.R.L.
Emerainville - France
T: +33 1 64 02 50 28
Kipp & Zonen USA Inc.
Bohemia - USA
T: +1 631 589 2065
Kipp & Zonen Asia Pacific Pte. Ltd.
T: +65 6748 4700