Chemical Transformation and Optical Properties of Aerosols From Urban Areas During the TexAQS/GoMACCS Study
Abstract
Size-resolved, non-refractory (NR) aerosol composition was measured on a 10-second basis and with high sensitivity aboard the NOAA WP-3D aircraft using an Aerodyne Compact Time-of-Flight Aerosol Mass Spectrometer (C-ToF AMS) during the 2006 Texas Air Quality Study/Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS/GoMACCs). Fine features in the C-ToF AMS data were highly correlated with independent measurements of submicron aerosol volume and dry extinction. There are emissions of several secondary aerosol precursors in the Houston area: sulfur dioxide (SO2) from industrial facilities and isolated power plants as well as volatile organic compounds (VOCs) from industrial facilities mainly along the ship channel and from other urban sources. Downwind of Houston, there is a clear progression of increasing aerosol mass as a function of distance, with both sulfate and organic material being formed. However, the complexity of the Houston area sources produces an inhomogeneous composition of the aerosol downwind, also depending on the upwind source. Since the sources of SOA (secondary organic aerosol) precursors cover a large area whereas SO2 is emitted from point sources, the urban area generally produces broadly distributed SOA with narrow, high mass concentrations of sulfate aerosol in the first several hours downwind. In contrast, Dallas is more typical of urban areas with VOCs from mobile emissions as the main precursor of secondary aerosol. Hence, downwind of Dallas the aerosol is more homogeneous in composition and primarily organic. The hygroscopic and optical properties of the aerosol, as it is transformed downwind of both urban areas, will also be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.A24C..04M
- Keywords:
-
- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0345 Pollution: urban and regional (0305;
- 0478;
- 4251);
- 0360 Radiation: transmission and scattering;
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry