HR: 0800h
AN: A51D-0100    [Abstracts]
TI: Measurement of HO₂NO₂ in the upper troposphere during INTEX-NA
AU: Kim, S
EM: skim@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences,Georgia Institute of Technology, 311 Ferst Dr. Atlanta, Atlanta, GA 30332 United States
AU: * Huey, L G
EM: greg.huey@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences,Georgia Institute of Technology, 311 Ferst Dr. Atlanta, Atlanta, GA 30332 United States
AU: Stickel, R E
EM: robert.stickel@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences,Georgia Institute of Technology, 311 Ferst Dr. Atlanta, Atlanta, GA 30332 United States
AU: Crawford, J H
EM: james.h.crawford@nasa.gov
AF: NASA Langley Research Center, Main Stop 144, Hampton, VA 23681 United States
AU: Chen, G
EM: gao.chen-1@nasa.gov
AF: NASA Langley Research Center, Main Stop 144, Hampton, VA 23681 United States
AU: Olson, J R
EM: j.r.olson@larc.nasa.gov
AF: NASA Langley Research Center, Main Stop 144, Hampton, VA 23681 United States
AU: Brune, W H
EM: brune@meteo.psu.edu
AF: Department of Meteorology, Penn State University, 503 Walker Building, University Park, PA 16802 United States
AU: Ren, X
EM: xur1@psu.edu
AF: Department of Meteorology, Penn State University, 503 Walker Building, University Park, PA 16802 United States
AU: Wooldridge, P J
EM: pjwool@berkeley.edu
AF: Department of Chemistry and Department of Earth and Planetary Science,University of California, Berkeley, Latimer Hall, Berkeley, CA 94720 United States
AU: Bertram, T H
EM: tbertram@uclink.berkeley.edu
AF: Department of Chemistry and Department of Earth and Planetary Science,University of California, Berkeley, Latimer Hall, Berkeley, CA 94720 United States
AU: Perring, A
EM: aperring@uclink.berkeley.edu
AF: Department of Chemistry and Department of Earth and Planetary Science,University of California, Berkeley, Latimer Hall, Berkeley, CA 94720 United States
AU: Cohen, R C
EM: rccohen@berkeley.edu
AF: Department of Chemistry and Department of Earth and Planetary Science,University of California, Berkeley, Latimer Hall, Berkeley, CA 94720 United States
AU: Lefer, B L
EM: blefer@uh.edu
AF: Department of Geosciences, University of Houston, 4800 Calhoun Rd., Houston, TX 77204 United States
AU: Shetter, R E
EM: shetter@ucar.edu
AF: NCAR, 1850 Table Mesa Dr, Boulder, CO 80305 United States
AB: The first direct in situ measurements of HO₂NO₂ in the upper troposphere were performed from the NASA DC-8 during INTEX-NA 2004. These measurements provide an independent diagnostic of HOx chemistry in the free troposphere to complement direct observations of HO_x. On average, the highest HO₂NO₂ mixing ratio of 76 pptv (median = 77pptv, 1-sigma = 39 pptv) was observed at altitudes of 8-9 km. HO₂NO₂ levels were lower above and below this altitude. Simple steady state calculations of HO₂NO₂, constrained by measurements of HO_x, NO_x and J values, are in good agreement (slope = 0.98, R² = 0.63 z = 5.5-7.5 km) with measurements at lower altitudes where thermal decomposition is the major loss process. Above 8 km these calculations are in poor agreement with measured values (R²= 0.21) and are typically larger by a factor of three. Steady state calculations of HO₂NO₂ using model predicted HO_x are in better agreement but are larger than measured values by 60% on average. However, the ratio of HO₂NO₂ to NO₂ is found to have a striking correlation to the ratio of predicted HO₂ to OH. Potential reasons for the discrepancies between predictions and measurements will be discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005