Measurement and Analysis of Optical Extinction Properties
Document ID: 18
Master's Thesis
The Pennsylvania State University
The Graduate School
Department of Electrical Engineering
Abstract
Remote sensing techniques can be used to characterize airborne particulate matter and results have been compared with atmospheric extinction, aerosol optical depth, and particle size distribution measurements from other sensors. Lidar was used to measure atmospheric constituents and provide a continuous monitor of the optical properties in the lower atmosphere during the NEOPS-DEP campaign of 2002. These studies were conducted in the Philadelphia urban environment where a combination of pollution sources exists. The PSU Lidar Atmospheric Profile Sensor (LAPS) measured ozone, water vapor, temperature, and optical extinction. LAPS was also used to measure vertical profiles of the Angstrom exponent using scattering and extinction data. The Met (Meteorological) tower included a radiometer that measured solar irradiance, from which transmittance values were derived. The Millersville University nephelometer and the Clarkson University optical scatter instruments were used to measure the single scattering albedo and Angstrom exponent. Optical extinction plots from LAPS, at both visible and ultraviolet wavelengths, are integrated and smoothed to obtain vertical profiles. Transmittances obtained from these vertical profiles are found to generally agree with solar transmission from radiometric data. The aerosol optical depths from extinction profiles measured using LAPS and the Met tower data are found to be consistent with the Millersville University nephelometer scattering coefficients. Finally, the single scattering albedo is calculated from the Millersville University nephelometer and the Angstrom exponent is calculated for LAPS and the Millersville University nephelometer. These parameters are compared with the extinction and scattering from LAPS, as well as the scattering form the Millersville University nephelometer and the carbon and PM profiles from the Clarkson University surface sensors. Analysis of the single scattering albedo and the Angstrom exponent for various episodes provides a better understanding of the relationship between atmospheric pollution episodes and particle size distribution.
Keywords: optical extinction, lidar atmospheric profile sensor (LAPS), lidar
| Citation: | S. Unni, "Measurement and Analysis of Optical Extinction Properties", The Pennsylvania State University, Master's Thesis, December 2003, 97 pages |