Instrument Specifications

Response Time:
Characterized by the time during which the instrument reaches 95% of the final value. Eppley performs this test by capping the instrument in full sun and timing the drop to zero.

Zero Off-Set (a):
Test (a) is for cases when the net thermal radiant flux density is 200Wm-2 such as when the instrument is at 30°C and the sky is temperature -10°C. Eppley performs this test in our Blackbody Calibration System.

Zero Off-Set (b):
Test (b) is the result of a 5 degree change in temperature over one hour and is performed in Eppley’s temperature chamber.

Non-Stability:
The change in sensitivity per year is best done through observational data.

Non-Linearity:
The deviation of sensitivity from low intensity (100 Wm-2) to high intensity (1000 Wm-2) is tested on Eppley High Intensity Lamp Bench.

Directional Response:
The cosine response of the Pyranometers is also tested on the High Intensity Lamp Bench at Eppley.

Spectral Selectivity:
Eppley has independently tested the Schott Glass WG295 hemispheres as well as the Black Optical Lacquer to assure uniform spectral transmittance from 0.3 to 2.8 microns.

Temperature Response:
Temperature Dependence Tests are performed in Eppley’s Temperature Chambers. Note that while the tests are often -30°C to +50°C, these are not the operational limits of the instruments. These instruments can be used in hotter (or colder) climates but you may wish to contact Eppley for a special temperature dependence test in these extreme climate areas.

Tilt Response:
The change of sensitivity as a result of orientation is…