Schelt Technology

Net radiation is the sum of the four components shown tothe left (incoming shortwave, outgoing shortwave, incominglongwave, outgoing longwave). Incoming shortwave incidenton the surface is either reflected or absorbed by the surfacematerial, and longwave radiation is emitted from the surfaceand emitted from the molecules of air in the atmosphere.Typical clear sky summer fluxes over grass and clear sky winterfluxes over snow are shown. A typical summer flux at solarnoon would be +650 W m−2; in winter it would be 0 W m−2.

LPNET14 is a 4-component net-radiometer for the measurement of thenet radiation between 0.3 μm and 45 μm.The net-radiometer consists of two pyranometers (one for the measurementof the global radiation Esw↓ and the other one for the measurement ofthe reflected solar radiation Esw↑ ) and a pair of pyrgeometers (one for themeasurement of the infrared radiation emitted by the sky EFIR↓ and theother one for the infrared emitted by the ground surface EFIR↑).The LPNET14 is equipped with a temperature sensor (NTC). Themeasurement of the temperature is needed for the measurement withthe two pyrgeometers, in fact, the far infrared is derived by measuring thethermopile output and by the knowledge of the instrument’s temperature.The net radiometer is suitable for outdoor use in all weather conditionsand requires little maintenance.