HR: 1340h
AN: A33D-1558    [Abstracts]
TI: Influence of Black Carbon on Photolysis Rates and Ozone Production Rates in an Urban Environment
AU: * Stark, H
EM: harald.stark@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: * Stark, H
EM: harald.stark@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AU: Schwarz, J P
EM: Joshua.P.Schwarz@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Schwarz, J P
EM: Joshua.P.Schwarz@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AU: Spackman, J R
EM: Ryan.Spackman@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Spackman, J R
EM: Ryan.Spackman@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AU: Ryerson, T B
EM: Thomas.B.Ryerson@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Holloway, J S
EM: John.S.Holloway@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Holloway, J S
EM: John.S.Holloway@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AU: Parrish, D D
EM: David.D.Parrish@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Parrish, D D
EM: David.D.Parrish@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AU: Fahey, D W
EM: David.W.Fahey@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Fehsenfeld, F C
EM: Fred.C.Fehsenfeld@noaa.gov
AF: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, United States
AU: Fehsenfeld, F C
EM: Fred.C.Fehsenfeld@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, CO 80309, United States
AB: Tropospheric ozone (O₃) is a key compound influencing urban air quality. It is produced by the reaction of oxygen atoms (O) with oxygen molecules (O₂). In the troposphere, oxygen atoms are primarily produced by photolysis of nitrogen dioxide (NO₂). The presence of aerosols, in particular black carbon (BC), has previously been shown to reduce nitrogen dioxide photolysis rates. It has been suggested that ozone concentrations can be reduced by up to 20% because of the reduction in photolysis rates by BC. In this work, we will present results from the NOAA WP-3 research aircraft participating in the 2006 Texas Air Quality Study (TEXAQS2006). On board the aircraft, spectral actinic fluxes from 280 to 690 nm were measured at 1 Hz using a spectroradiometer. Photolysis rates of 19 compounds, including nitrogen dioxide and ozone, were calculated from the spectral actinic fluxes. Black carbon mass concentrations were measured at 1 Hz using a Single-Particle Soot Photometer (SP2). Photolysis rates were reduced by up to 30% under high BC mass loadings during the measurement campaign. Box model calculations of the tropospheric ozone chemical mechanism, including various precursors, e.g. CO, NO, and NO₂, help to describe how these significant reductions in photolysis rates influenced ozone production rates during TEXAQS2006. We will also discuss the impact of black carbon on photolysis rates and ozone production in urban areas in general.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting