HR: 10:20h
AN: A22C-01 INVITED    [Abstracts]
TI: Urban Pollution in the Nocturnal Boundary Layer: Chemical Processing and Vertical Transport
AU: * Stutz, J
EM: jochen@atmos.ucla.edu
AF: University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Math Sciences 7127, Los Angeles, CA 90095-1565, United States
AU: Flynn, C J
EM: connor.flynn@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, United States
AU: Rappenglück, B
EM: brappenglueck@uh.edu
AF: University of Houston, Department of Geosciences, 4800 Calhoun Rd., Houston, TX 77204-5007, United States
AU: Lefer, B
EM: blefer@uh.edu
AF: University of Houston, Department of Geosciences, 4800 Calhoun Rd., Houston, TX 77204-5007, United States
AU: Brune, W H
EM: brune@meteo.psu.edu
AF: Penn State University, Department of Meteorology 504 Walker Building, University Park, PA 16802, United States
AU: Dibb, J E
EM: jack.dibb@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Morse Hall 39 College Road, Durham, NH 03824-3525, United States
AU: Griffin, R J
EM: rjg@gust.sr.unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Morse Hall 39 College Road, Durham, NH 03824-3525, United States
AB: For many decades research on urban pollution and its chemistry has concentrated on processes occurring during the day. In recent years, however, it has become clear that transport and chemical processing at night can also play an important role for urban air quality. Various chemical pathways are known to remove gaseous pollutants, such as nitrogen oxides, ozone and hydrocarbons, as well as influence aerosol composition at night. The quantification of these processes is difficult due to the influence of vertical stability, which leads to a much slower vertical transport of trace gases emitted at the surface at night than during the day. As a consequence, chemistry at night is often very altitude dependent, making investigations in the NBL challenging.
In recent years a number of field experiments have been performed where the nocturnal meteorology and the vertical distribution of the dominant trace gases at night have been observed. Here we will review the lessons learned in past studies and present results from a recent study in Houston, TX, which gives new insights into the meteorological and chemical processes at night. The TexAQS II Radical Measurement Project (TRAMP) was performed in August and September 2006, on the University of Houston campus. We will present data from a number of measurements, including a long-path Differential Optical Absorption Spectrometer, in situ instrumentation for gas phase compounds (O₃, NO, NO₂, CO, VOC), HO_x radicals, aerosol size and composition, various meteorological and radiation parameters, and an aerosol LIDAR. The field observations will be compared to 1D model calculations which show the dominant chemical processes and allow the identification of gaps in our understanding of the polluted nocturnal urban boundary layer.
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting