Kipp & Zonen CMP 3 Instruction Manual

Also see for CMA 11: Instruction manual

Kipp & Zonen CMP 3 Instruction Manual Manual pdf 37 page image

Appendix A. Pyranometer physical propertiesA.1 Spectral rangeThe spectrum of the solar radiation reaching the Earth’s surface is in the wavelength range between 280 nm and 4000 nm,extending from ultraviolet (UV) to the far infrared (FIR). Due to the excellent physical properties of the glass dome(s) and blackabsorber paint, Kipp & Zonen CMP and CMA series radiometers are equally sensitive in a wide spectral range. 97 - 98% of thetotal energy will be absorbed by the thermal detector.A.2 SensitivityThe radiometer thermopile sensitivity is mainly determined by the physical properties of the detector itself. The thermoelectricpower, thermal conductivity of the junctions and the overall dimensions of the sensing element are related to its sensitivity. Thesensitivity is determined under standard conditions, and compared with a reference, that are stated on the calibration certificate.A.3 Response timeAny measuring device requires a certain time to react to a change in the parameter being measured. The radiometer requires timeto respond to changes in the incident radiation. The response time is normally quoted as the time for the output to reach 95 %(sometimes 1/e, 63 %) of the final value following a step-change in irradiance. It is determined by the physical properties of thethermopile and the radiometer construction.A.4 ImpedanceThe radiometer impedance is defined as the total electrical impedance at the radiometer output connector fitted to the housing. Itarises from the electrical resistance in the thermal junctions, wires, connections, and passive electronics within the radiometer.A.5 Non-linearityThe non-linearity of a pyranometer is defined in ISO 9060:1990 as the percentage deviation in the sensitivity over an irradiancerange from 100 to 1000 W/m² compared to the sensitivity at the calibration irradiance of 500 W/m². The non-linear effect is largelydue to convective and radiative heat losses at the black absorber surface which make the conditional thermal equilibrium of theradiometer non-linear.Response [arbitrary units]300200100000.51.0400 500 1000 2000 3000 4000Solar radiation spectrum at sea levelSpectral response of CMP 3Spectral response of CMP 6, CMP10, CMP 11, CMA 6 and CMA 11Spectral response of CMP 22Wavelength [nm]37