Calibration of near-infrared absorption band for a sun-photometer
近红外大气吸收波段太阳辐射计定标

The atmospheric transmittance properties for three near-infrared channels of POM02 skyradiometer at the wavelengths of 1020 nm, 1627 nm, and 2200 nm, were studied by using a combined atmospheric radiative transfer model (CART). Results showed that, the extinctions at the bands of 1020 nm, 1627 nm, which are located in atmospheric window channel, obeyed the Beer-Lambert law. For the 2200 nm channel located in an absorption band, the absorption exhibited an exponential distribution. Then these channels of POM02 skyradiometer were calibrated with traditional Langley method and modified Langley method, respectively. Two calibration methods were applied for four clear days. It proved that the accuracy of derived transmittance has been improved by 3.8% using modified Langley method to 2200 nm channel.