FTIR extinction spectroscopy of mineral dust aerosol

 

FTIR extinction spectroscopy of mineral dust aerosol

        Mineral dust aerosol plays an important role in the climate system. The effect of atmospheric dust on climate is studied by various remote sensing techniques. It is important to take radiative effect of mineral dust aerosol into account in order to process the remote sensing data correctly. Simulations of the extinction spectra of major components of mineral dust as well as authentic dust samples show that currently used Mie theory does not accurately reproduce the peak position or 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. Spectral simulations, derived from Rayleigh theory for different shape models 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 

 

Figure 1. Experimental infrared spectrum of Iowa loess and Saharan Sand compared to Mie and analytical solutions.
Figure 2. The relative ratio of the integrated area for Mie and analytic solutions to the experimental spectrum for Iowa loess (IL) and Saharan sand (SS) for narrow band IR channels BT8, BT11 and BT12 of HIRS/2, MODIS, AVHRR and GOES-8 sensors.