Weather measurement system using near‐infrared differential spectroscopy.

A weather measurement system was constructed using near‐infrared light‐emitting diodes and indium gallium arsenide photodiodes for the 1–2 µm near‐infrared region. The difference in the absorbance of water for near‐infrared light at wavelengths of 945 and 1450 nm was used to distinguish between three different precipitation types: snow, sleet and rain. From the ratio of the number of generated light absorption events at the two wavelengths, a distinction between snow, sleet and rain events was demonstrated. The judgement results by this system were consistent with those obtained from the meteorological observatory weather database. [ABSTRACT FROM AUTHOR]