The CGR 3 is a pyrgeometer, designed for meteorological measurements of downward atmospheric long wave radiation. The CGR 3 provides a voltage that is proportional to the net radiation in the far infrared (FIR). By calculation, downward atmospheric long wave radiation is derived. For this reason CGR 3 embodies a temperature sensor. The CGR 3 uses a specially designed silicon window. On the inside a solar-blind filter blocks solar radiation. The CGR 3 data represents the radiation exchange within the whole hemisphere. This is because the reference CGR 3 is calibrated outdoors with respect to a reference CG 4, which has a 180 degrees field of view.
The CGR 3 has been improved in many points over the CG 3, based on customer feedback and years of experience. The CGR 3 has a newly designed sunscreen that covers both body and connector to reduce the instrument temperature and further increase the accuracy. The design of the instruments accounts for the use of existing Kipp & Zonen mounting plates.