Analysis of the vertical structure and size distribution of dust aerosols over the semi-arid region of the Loess Plateau in China
Author:
Zhou B.,Zhang L.,Cao X.,Li X.,Huang J.,Shi J.,Bi J.
Abstract
Abstract. Using measurements of dual-wavelength polarisation lidar, particle sizer, and nephelometer from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), the properties of dust aerosol extinction coefficient, optical depth, depolarisation ratio, colour ratio, size distribution, and concentration over the semi-arid region of the Loess Plateau in north-western China are analysed in a case study of dust storms from 16–18 March 2010. The results show that dust aerosols are distributed mostly within the lower layer (below 3.0 km), with the dust aerosol extinction coefficient ranging from 0.1 to 1.0 km−1. The average optical depth and depolarisation ratio are near 0.6 and 0.3, respectively, while the colour ratio ranges from 0.8 to 1.0. The mass size distribution of dust aerosols has two peaks at 0.7 μm and 5.0 μm, respectively, while the number size distribution of dust aerosols is log-normal with a maximum near 0.8 μm. Particles in the fine mode (r ≤ 2.5 μm) are predominant in the dust storm. Their number concentration decreases while those of particles in the moderate (2.5 μm < r ≤ 10.0 μm) and coarse (10.0 μm < r ≤ 20.0 μm) modes increase. Based on Mie theory and the number size distribution of the aerosol, the dust aerosol scattering coefficient and its variation with particle size are calculated and analysed. A fairly close correlation is found with that measured by the nephelometer, for which the correlation coefficients are 0.89 and 0.94, respectively, at 520 and 700 nm. It shows a Gaussian distribution of dust aerosol scattering coefficient against effective diameter, with a fitting coefficient of 0.96 and centre diameter of 5.5 μm. The contribution percentages of aerosol within fine, moderate, and coarse modes to dust aerosol scattering coefficient are 20.95%, 62.93%, and 16.12%, respectively, meaning that PM10 is a dominant factor in the dust aerosol scattering properties.
Publisher
Copernicus GmbH
Reference54 articles.
1. Ackerman, A. S., Toon, O. B., Stevens, D. E., Heymsfield, A. J., Ramanathan, V., and Welton, E. J.: Reduction of tropical cloudiness by soot, Science, 288, 1042–1047, https://doi.org/10.1126/science.288.5468.1042, 2000. 2. Bi, J. R., Huang, J. P., Fu, Q., Wang, X., Shi, J. S., Zhang, W., Huang, Z. W., and Zhang, B. T.: Toward characterization of the aerosol optical properties over Loess Plateau of Northwestern China, J. Quant. Spectrosc. Ra., 112, 346–360, 2011. 3. Chiang, C. W., Das, S. K., and Nee, J. B.: An iterative calculation to derive extinction-to-backscatter ratio based on lidar measurements, J. Quant. Spectrosc. Ra., 109, 1187–1195, 2008. 4. Chun, Y. S., Kim, J. R., Choi, J. C., Boo, K. N., Oh, S. N., and Lee, M. Y.: Characteristic number size distribution of aerosol during Asian dust period in Korea, Atmos. Environ., 35, 2715–2721, 2001. 5. Collis, R. T. H.: Lidar: a new atmosphere probe, Q. J. Roy. Meteor. Soc., 92, 220–230, 1966.
Cited by
2 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|