HR: 09:46h
AN: A31E-08    [Abstracts]
TI: Impact of Clouds and Aerosols on Photochemistry During the TexAQS II Radical and Aerosol Measurement Project
AU: * Flynn, J H
EM: jhflynn@uh.edu
AF: University of Houston, Department of Geosciences, 4800 Calhoun Road Room 312 SR-1, Houston, TX 77204, United States
AU: Lefer, B L
EM: blefer@uh.edu
AF: University of Houston, Department of Geosciences, 4800 Calhoun Road Room 312 SR-1, Houston, TX 77204, United States
AU: Rappenglueck, B
EM: brappenglueck@uh.edu
AF: University of Houston, Department of Geosciences, 4800 Calhoun Road Room 312 SR-1, Houston, TX 77204, United States
AU: Olson, J R
EM: jennifer.r.olson@nasa.gov
AF: NASA Langley Research Center, Chem & Dynamics Branch, Mail Stop 401B, Hampton, VA 23681, United States
AU: Chen, G
EM: gao.chen@nasa.gov
AF: NASA Langley Research Center, Chem & Dynamics Branch, Mail Stop 401B, Hampton, VA 23681, United States
AB: Photochemistry is responsible for the production of tropospheric ozone, the primary component of smog. In 2006, Houston, Texas experienced 20 days with a 1-hour ozone average in excess of 125 ppbv, and 36 days with an 8-hour average over 85 ppbv. Two models were used to assess the impact of clouds and aerosols on the photochemical production and loss of ozone and radicals in a polluted urban environment. The NASA Langley Research Center (LaRC) 0-D photochemical box model was used to assess the changes in the photochemical budgets due to varying cloud and aerosol conditions. The NCAR Tropospheric Ultraviolet and Visible (TUV) radiative transfer model was used to calculate photolysis frequencies for clear sky conditions with a variety of aerosol profiles. These tools were used to analyze the data set collected during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) with respect to ozone and radical budgets. Measurements of trace gasses, aerosols, meteorological parameters, and radiation were collected between mid-August and early October 2006 at the University of Houston. The photochemical model was run using various photolysis rates that reflect a range of atmospheric conditions impacting the actinic flux. Rates from real-time actinic flux measurements include the impact of both the clouds and aerosols that are present. Photolysis rates for clear-sky (cloud-free) conditions, both with and without aerosol profiles were calculated using the TUV radiative transfer model. A comparison of the photochemical ozone and radical budgets resulting from these different rates indicate those sensitivities to the presence of aerosols and clouds. Approximately seven of the 50 days during the campaign were cloud-free and were compared to LaRC-TUV results to show the effects of aerosols. The remaining days show the effects of both aerosols and cloud conditions that varied from partly cloudy to heavy overcast conditions. A cloud camera was used to categorize the sky condition based on coverage and type of clouds. Results from this work, particularly the results of the aerosol impacts, can be utilized in photochemical models to improve the closure between ozone measurements and both forecasts and hindcasts.
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0317 Chemical kinetic and photochemical properties
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