In this paper we presented the variation of atmospheric aerosol optical thickness and Angstrom exponent a (which symbolizes the width of particle spectrum) in Beijing in recent three years.是什么意思_In this paper we presented the variation of atmospheric aerosol optical thickness and Angstrom exponent a (which symbolizes the width of particle spectrum) in Beijing in recent three years.在线翻译_英语_读音_用法_例句