AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Three Dimensional Characteristics of Mineral Dust using Atomic Force Microscopy
XIN XIN WOODWARD, Ashima Chhabra, Will Cantrell, Michigan Technological University
Abstract Number: 705 Working Group: Aerosol Physics
Abstract Mineral dust in the atmosphere plays a role in Earth's climate through its ability to absorb and scatter radiation (both solar and terrestrial) and through its part in the hydrological cycle as cloud condensation and ice nuclei. The three dimensional characteristics of dust are particularly important for their part in Earth's radiative balance and, perhaps, for their role as ice nuclei. As examples, the optical properties of mineral clay aerosol are best fit by assuming that they are highly eccentric oblate spheroids (Meland et al., 2012) and the surface roughness of dust may determine their efficacy as ice nuclei (Hoose and Mohler, 2012).
Most sizing methods capture one or two dimensions for particles. In contrast to differential mobility analyzers, scanning electron microscopes and other devices, atomic force microscopes acquire information in three dimensions. We have investigated individual aerosol particles of both Arizona Test Dust and kaolinite and find that the asphericity is quite pronounced. The height of most particles is typically a factor of five to ten smaller than the average dimension in the projected area. We will present analysis of detailed, three dimensional images of both Arizona Test dust and kaolinite. In particular, we will show the asphericity for the dusts as well as discuss the surface roughness for each.