Results of Aerosol Optical Depth (AOD) measurements for the Damxung region, the Tibetan Plateau are presented. The measurements were performed with a multi-spectral photometer in the wavelength range 448.2~902.3 nm during May/June of 1998. The AOD was found to be very low (≤0.1) and had a good positive correlation with relative moisture. They exhibit larger diurnal as well as day-to-day variations at all wavelengths in dry seasons than in wet seasons. Also a general decreasing trend was seen in the AOD from...