Optical properties and size distribution of dust aerosols over the Tengger Desert in Northern China

Abstract

A field experiment was performed during 1 April-30 September 2001 in the southeast Tengger Desert in Northern China to measure the solar radiant flux by a solar direct radiometer and a multi-wavelength sun-photometer. The observation and research results are as follows. On fine days, dust aerosols attenuate the direct solar radiant flux by 2.6-47.0%, with an average of 16.9%. On dusty days, dust aerosols attenuate the direct solar radiant flux by 10-90%, with an average of 38%. The mean atmospheric turbidity for broadband (300-4000 nm) flux is 0.26 for fine days and 0.74 for dusty days. Under the typical background, floating dust, and dust storm weather conditions, the aerosol optical depths (AODs; at 550 nm) are about 0.1, 0.9, and 2.0, and the Ångström exponents are about 2.0, 0.38, and -0.24, respectively. The mean AOD of the examples is 0.66, and 0.87 for the Ångström exponents. On dusty days, the aerosol number concentration is 2-10 times higher than that on fine days. The aerosol size distribution is a multi-normal distribution during dusty conditions, while the aerosol size distribution is a logarithmic normal distribution during fine weather. © 2005 Elsevier Ltd. All rights reserved.