近红外大气吸收波段太阳辐射计定标

Calibration of near-infrared absorption band for a sun-photometer

用通用大气辐射传输软件CART模拟了POM02太阳辐射计的1020nm、1627nm和2200nm等3个近红外通道的大气透过率特性。结果表明,前两通道处于大气非吸收波段,其透过率很好的遵从Beer-Lambert定律,而2200nm通道则有较强的吸收,吸收光学厚度随大气质量的变化服从指数分布,与Beer-Lambert定律有一定的偏差,其定标需采用改进的Langley法。通过选取好天的5个定标实例证明,采用改进的Langley法定标2200nm通道,可提高其透过率测量精度约3.8%。

The atmospheric transmittance properties for three near-infrared channels of POM02 skyradiometer at the wave-lengths 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.