Aerosol optical properties at Nam Co, a remote site in central Tibetan Plateau

To reduce uncertainties in the assessment of aerosol effects on regional climate and validate the satellite products, aerosol optical measurements were made at a remote site, Nam Co Station (AERONET) in central Tibetan Plateau, since August 2006. Very low aerosol optical values were observed with annual mean Aerosol Optical Depth (AOD) of 0.05 at 500 nm during August 2006 to July 2007. Angstrom parameters were also low with an average of 0.42 +/- 0.27, Angstrom parameter varies greatly over a narrow range of AOD, indicating the occurrence of different types of aerosol particles. The seasonal variation of the monthly average AOD shows maximum values in the spring (April, May) and remains high values in summer monsoon season (June, July, August, and September). The former corresponds to the prevalence of soil dust particle in spring and the later reflects the enhanced human activities in summer. The seasonal variation of columnar size distribution is also consistent with this result. Distinct seasonal variation of water vapor content was observed, with high that occurred in summer monsoon season. Nam Co appears to represent a clean continental background site for atmospheric composition investigation. This work could fill the gap which exists in our knowledge on the global aerosol distribution over the huge high elevation area (i.e. Tibetan Plateau). (C) 2008 Elsevier B.V. All rights reserved.