Shortwave global radiation
Pyranometer experimental test
KNMI currently operates Kipp & zonen CM-11 pyranometers in its network to measure the global shortwave radiation from the sun. These sensors have been in use since 1989, and development in pyranometer technology has taken advances since its introduction. Despite the sensors are still functional, being exposed to the Dutch weather conditions for such a long time tells us that they are in need of replacement.
In order to evaluate sensors, a test is being conducted using a series of pyranometers from several manufacturers. This gives us an opportunity to investigate performance of several sensors. Furthermore, this gives us an opportunity to evaluate several aspects in solar radiation measurements. For example, the quality of the currently operated Kipp & zonen CM-11 sensors can be determined more accurately, the impact of meteorologic effects such as dew and rime can be quantified, the benefit of sensor ventilation can be quantified, and perhaps more unexpected outcomes.
The instruments are placed at the KNMI Baseline Surface Radiation Network (BSRN) site at Cabauw research location. Here a variety of high quality instruments are already available. Examples are the Kipp & zonen CH1 pyrheliometer that measures the direct solar radiation, the shaded and ventilated CM-22 pyranometer measuring the diffuse solar radiation, an unshaded and ventilated CM-22 for the global radiation, both upward and downward, Kipp & zonen CGR-4 radiometers for the longwave (infrared) radiation, both upward and downward, along with other meteorologic variables, such as wind and temperature. This makes it a unique location for executing a pyranometer test. More information on the BSRN site is available here.
Currently the following sensors are installed:
Quicklooks from the BSRN site (updated every hour)