Friday, 13 November 2009
In situ characterization of aerosols using optical methods plays a vital role in air quality studies. Semi-arid regions, such as El Paso, Texas, exhibit a high concentration of mineral dust particles in the atmosphere. The El Paso-Juarez Airshed is also affected by anthropogenic and biogenic emissions. In this work we present retrieval results of optical parameters, such as single scattering albedo and the asymmetry parameter, in addition to aerosol size distribution for the El Paso-Juarez Airshed. We have used the Tropospheric Ultra Violet Model (TUV) and the Environmental Physics Inverse Reconstruction Model (EPIRM) in conjunction with Multi-filter Rotating Shadowband Radiometer (MFRSR) Irradiance data for the El Paso-Juarez Airshed. Aerosol optical depths values were obtained using MFRSR instruments located in the city of El Paso. Retrievals for aerosol single scattering albedo (ùaer) were obtained using TUV calculations of the direct to diffuse irradiance ratio, and comparing them against MFRSR corresponding irradiance data. Size distributions were obtained using the EPIRM model. The latter uses Twomey's regularization technique, which suppresses ill-posedness by imposing smoothing and non-negativity constraints on the desired size distributions. Furthermore, T-matrix calculations are also used to obtain extinction coefficients. Based on the aerosol concentration and environmental conditions, three representative cases were selected for our studies: clean days, dirty days and windy days. This work will lead to better characterization of aerosols in similar regions. In addition, it can provide a more accurate assessment of regional aerosol transport and better boundary conditions for air quality models.
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