AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Infrared Extinction Spectra of Mineral Dust Aerosol
OLGA LASKINA, Jennifer Alexander, Mark Young, Paul Kleiber, Vicki Grassian, University of Iowa
Abstract Number: 101 Working Group: Aerosol Physics
Abstract Mineral dust aerosol plays an important role in the Earth's radiative budget. It affects the atmosphere by absorbing and scattering radiation. The effect of atmospheric dust on climate is studied by various remote sensing techniques. Key atmospheric properties are determined based on measurements from narrow band IR channels of satellites. It is important to take radiative effects of mineral dust aerosol into account to correctly process remote sensing data. In this study, Fourier transform infrared (FTIR) extinction spectra and aerosol size distributions have been simultaneously measured for authentic dust samples. The mineralogy of complex samples was inferred using linear combination of FTIR spectra. Spectral simulations were carried out using both Mie theory and solutions derived in the Rayleigh regime for specific particle shapes. Simulations of the extinction based on Mie theory shows that it does not accurately reproduce the peak position and band shape of the prominent IR resonance features. Moreover, it tends to considerably underestimate the integrated absorbance in important narrowband satellite channels. Errors in simulated peak position and line shape associated with Mie theory could adversely affect determination of mineral composition based on IR satellite data. Analytic solutions for various shapes derived from Rayleigh theory offer a better fit to the major band features of the spectra, therefore the accuracy of modeling atmospheric dust properties might be improved by using these analytic solutions.