AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Use of Cavity Ring-Down Spectroscopy to Quantify Mineral Dust Optical Properties
Daniel P. Veghte, MIRIAM A. FREEDMAN, The Pennsylvania State University
Abstract Number: 449 Working Group: Instrumentation and Methods
Abstract It is currently unknown whether the direct effect of mineral dust aerosol results in a net warming or cooling of the Earth system. This uncertainty arises in part due to the varied composition and shape of dust aerosol as well as particle aging during atmospheric transport. Cavity ring-down spectroscopy is currently the most sensitive technique available to measure aerosol optical properties, but it has only rarely been used to quantify the extinction cross sections of non-spherical particles. We have used a combination of cavity ring-down spectroscopy, transmission electron microscopy, and computation to determine the extinction cross sections of size-selected calcium salts and other mineral dust species. We find that microscopy is essential for the determination of experimental parameters for cavity ring-down spectroscopy. For irregularly shaped calcium carbonate particles, we see little deviation from the optical properties of spherical particles. Our results demonstrate a method that can be used to extend cavity ring-down spectroscopy for the measurement of the optical properties of non-spherical particles.