First class albedometer ISO9060

The PCTRA068 albedometer measures the net global radiation, as well as the albedo of grounds (albedo is the ratio between diffuse radiation from a determined surface and the quantity of radiation that arrives on the surface).

The sensor is manufactured by mounting two pyranometers in one housing only. The two pyranometers, one measuring the incident radiation striking the ground and the other one measuring the reflected radiation, are combined in such a way to have the same sensitivity.

The signals of the two pyranometers are obtainable from the output cable. These signals can be processed to get the desired physical quantity.

The albedometer can be used as a pyranometer for measuring global radiation, it falls into the First Class pyranometers meeting ISO 9060 specifications and the criteria of WMO “Guide to meteorological Instruments and Methods of Observation”, fifthedition (1983).

The albedometer is based on a pair of thermopile sensors, one of them measuring the incident radiation on the ground and the other one the reflected radiation. Each thermopile works as an independent pyranometer.

The thermopile sensitive surface is coated with a black matt paint, which allows the pyranometer not to be selective at different wave lengths. The pyranometer spectral range is determined by the transmittance of the two glass domes type K5. Radiant energy is absorbed by the thermopile black surface, creating a difference of temperature between the center of the thermopile (hot junction) and the pyranometer body (cold junction).

The difference of temperature between hot and cold junction is converted in a Difference of Potential thanks to the Seebeck effect. In order to grant the thermopile a proper thermal insulation from the wind and to reduce sensitivity to thermal irradiance, the PCTRA068 is equipped with two concentric domes on each side, having a diameter of 50mm and 30mm, respectively.

The domes protect the thermopile from the dust, which, laying down on the black surface, might change the spectral sensitivity.

Through an external interface the signal generated by the sensor can be converted into a standard electrical signal (current or voltage). Note: must be purchased an amplifier module for each electrical output.

First class albedometer