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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL MANAGEMENT FOR SUSTAINABLE AGRICULTURAL SYSTEMS THAT PREVENT WIND EROSION AND ENHANCE THE ENVIRONMENT

Location: Wind Erosion and Water Conservation Research

Title: Optical Properties of Aeolian Dusts Common to West Texas

Authors
item Ma, Lulu -
item Hsieh, Daniel -
item ZOBECK, TEDDY
item Holder, Harold
item Thompson, Jonathan -

Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 2011
Publication Date: November 1, 2011
Citation: Ma, L., Hsieh, D., Zobeck, T.M., Holder, H.D., Thompson, J. 2011. Optical properties of aeolian dusts common to West Texas. Aeolian Research. 3(2):235-242.

Interpretive Summary: Computer models suggest that historical events such as the Dust Bowl and volcanic eruptions emit considerable airborne dust particles that can play an important role in climate change through direct and indirect effects on how the dust affects light. Soil dust generated by wind-related processes represent a large part of the total amount of airbornec particles. An understanding of how these dust particles affect light is needed to help is understand how the particles affect climate change. This research study utilized a dust generator device and several optical instruments to measure certain optical properties of airborne dust created by the Amarillo and Pullman soil types native to the panhandle of Texas, USA. Values for an optical property called the mass-extinction coefficient ranged between 1.74 m2/g and 2.97 m2/g when measured at a wavelength of 522 nm. A measure of the reflected light called the single-scatter albedo (SSA) ranged from 0.947 – 0.980 at visible wavelengths for both soil types with SSA increasing at longer wavelengths. Another optical property called the angstrom absorption exponent was measured as 1.73 for Pullman and 2.17 for Amarillo soil. Another optical property called the angstrom extinction exponent was 0.110 and 0.168 for the Pullman and Amarillo soil types, respectively. The optical properties reported may be of use for optical based estimates of soil erosion and aid in understanding how regional soil dusts may alter dust transport presently and during historical events such as the Dust bowl era.

Technical Abstract: Both recent models and historical events such as the Dust Bowl and volcanic eruptions have illustrated aerosols can play a significant role in climate change through direct and indirect optical effects. Soil dust aerosols generated by Aeolian processes represent a significant fraction of the total mass burden of atmospheric particles. Central to a better understanding of the climate effects of dust aerosols is knowledge of their optical properties. This research study utilized a dust generator and several instruments to determine certain optical properties of aeolian dust mimics created by the Amarillo and Pullman soil types native to the panhandle of Texas, USA. Values for the mass-extinction coefficient ranged between 1.74 m2/g and 2.97 m2/g at 522 nm depending on how mass concentration was determined. Single-scatter albedo (SSA) for both soil types ranged from 0.947 – 0.980 at visible wavelengths with SSA increasing at longer wavelengths. Angstrom absorption exponents were measured as 1.73 for Pullman and 2.17 for Amarillo soil. Observed Angstrom extinction exponents were 0.110 and 0.168 for the Pullman and Amarillo soil types. The optical properties reported may be of use for optical based estimates of soil erosion and aid in understanding how regional soil dusts may alter radiative transport presently and during historical events such as the Dust bowl era.

Last Modified: 9/10/2014
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