Airborne Particulate Matter in the Urban Environment during Summer in the Northeast United States
Document ID: 106
Master's Thesis
The Pennsylvania State University
The Graduate School
Department of Electrical Engineering
Abstract
Laser remote sensing techniques have been used to investigate atmospheric optical characteristics and to provide a means of describing the effects of local air pollution events. The North American Research Strategy for Tropospheric Ozone – North East – Oxidant and Particle Study (NARSTO-NE-OPS) study conducted in an urban area of Philadelphia, U.S. provided a chance to apply several of Penn State University’s LIDAR instruments to investigate optical properties of the lower troposphere. The Lidar Atmospheric Profile Sensor (LAPS) unit measured ozone, water vapor, temperature, direct backscatter, and extinction; the Micro Pulse Lidar (MPL) measured backscatter; and the Multistatic Atmospheric Particle Profiler (MAPP) measured intensity from an off-axis angle and estimated particle size distribution. Analysis of data from several days during three field research campaigns are used to show how remote sensing can be used to characterize atmospheric aerosols for pollution modeling. Direct backscatter profiles distinguish areas of strong signal return from regions of dense concentrations of aerosols, such as clouds, mist, fog, or haze. Pollution and haze events demonstrate the capabilities of lidar to characterize optical properties of atmospheric aerosols. Comparisons of water vapor and extinction plots from 19-22 August 1998 show convection within the lower troposphere as the planetary boundary layer expands after sunrise and aerosols mix downward from a higher altitude layer. The 284-nm extinction profiles from 07 August 1999 and 12 August 1999 show small diameter aerosols distributed within the lower troposphere, since shorter wavelengths v scatter more from small particles due to λ-4 dependence; while 530-nm extinction profiles display higher altitude clouds. These comparisons, between two transmitted wavelengths, allow aerosol mode estimates to be made. Lidar data from 16-17 August 1999 show how Philadelphia was affected by a northeast coastal haze event that extended from the Chesapeake Bay to Maine. Ultrafine aerosols are mixed from 0-2 km while fine and large mode aerosols form a ground layer between 0-250 m. MAPP images on 23 August 2001 display two distinct aerosol layers within the first 40 m of the atmosphere while 284- and 530-nm extinction plots show condensation growth of particles within the first 100 m of the atmosphere.
| Citation: | G. L. O'Marr, "Airborne Particulate Matter in the Urban Environment during Summer in the Northeast United States", The Pennsylvania State University, Master's Thesis, May 2002, 69 pages |