Variation of Aerosol Optical Properties over the Taklimakan Desert in China

The aerosol optical properties at the center of the Taklimakan Desert in Northwest China are investigated based on the measurements of aerosol optical depth (AOD) and Angstrom exponent from 2004 to 2008. A seasonal variation is found with high AOD and low Angstrom exponent values in spring and summer, due to the effect of dust storm events, and low AOD in autumn and winter. The maximum and minimum AOD occur in April (0.83 +/- 0.41) and November (0.19 +/- 0.10), respectively, with the maximum and minimum Angstrom exponent in January (0.70 +/- 0.25) and May (0.09 +/- 0.06), respectively. The diurnal variation of AOD (Angstrom exponent) shows the characteristic of high (low) values about 0.50-0.60 in the morning and evening, and is constant around 0.40 during daytime. The relationship between AOD and the Angstrom exponent can be fitted by a power equation with a R-2 of 0.55. The frequency distributions of AOD and the Angstrom exponent occurrence probability have a single peak distribution, and can be well fitted by a two-mode distribution.