Shape of atmospheric mineral particles collected in three Chinese arid-regions
Article first published online: 7 DEC 2012
Copyright 2001 by the American Geophysical Union.
Geophysical Research Letters
Volume 28, Issue 16, pages 3123–3126, 15 August 2001
How to Cite
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 13 JUN 2001
- Manuscript Received: 26 DEC 2000
The shape of atmospheric mineral particles of 0.1–6 µm radius was studied by electron microscopy applied to the samples collected in three arid regions in China (Qira in the Taklamakan Desert, Zhangye near the southern border of the Badain-Jaran Desert and Hohhot in northern China). In all three regions, the mineral particles showed irregular shapes with a median aspect ratio b/a (ratio of the longest dimension b to the orthogonal width a) of 1.4. Although the aspect ratio exhibited no clear size dependence, the circularity factor (4πS/l²; S is surface area and l is periphery length) tended to decrease with increasing radius, suggesting the presence of aggregated mineral particles at larger sizes. The ratio of particle height-to-width h/a was also evaluated by measuring the shadow length. The median ratio h/a was 0.49 in Hohhot, 0.29 in Zhangye and 0.23 in Qira. Analytical functions were fitted to the grand total of the frequency distributions of aspect ratios, height-to-width ratios and circularity factors allowing parametric calculations of radiative effects and calculations of optical and sedimentation behavior of mineral particles.