HR: 0800h
AN: A11B-0883    [Abstracts]
TI: Anomalies in the Distribution Patterns and Simulation of Aldehydes and PAN within Reacting Continental Outflow
AU: * Chatfield, R B
EM: Robert.B.Chatfield@nasa.gov
AF: NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035 United States
AU: Fried, A
EM: fried@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307 United States
AU: Heikes, B
EM: bheikes@gso.uri.edu
AF: Univ. of Rhode Island, Center for Atmospheric Chemistry Studies / GSO, South Ferry Road, Narrangansett, RI 02882 United States
AU: Anderson, B
EM: Bruce.E.Anderson@nasa.gov
AF: NASA Langley Research Center, MS 483, Hampton, VA 23681 United States
AU: Binkowski, F
EM: frank_binkowski@unc.edu
AF: Univ. of North Carolina, Chapel Hill, Carolina Environmental Program, Chapel Hill, NC 27599 United States
AU: Blake, D
EM: drblake@uci.edu
AF: University of California, Irvine, Dept. of Chemistry MC 2025, Irvine, CA 92697 United States
AU: Duncan, B
EM: Bryan.N.Duncan.1@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Mailstop 613.3, Greenbelt, MD 20771 United States
AU: Goldan, P G
EM: paul.d.goldan@noaa.gov
AF: NOAA Aeronomy Laboratory, R/AL 325 Broadway, Boulder, CO 80305 United States
AU: Singh, H B
EM: Hanwant.B.Singh@nasa.gov
AF: NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035 United States
AB: Key gas-phase organic breakdown products like formaldehyde (HCHO) and acetaldehyde (CH₃CHO) should behave similarly and predictably in continental outflow plumes. The INTEX-NA (ICARTT) and NARE-97 experiments provide a study set. We examine obervations and regional/global models describing the aldehyde species in low (0-4 km) continental outflow plumes. We find anomalies in their distributions, observed and modeled, which have improved our understanding of organic sources and preponderant reaction pathways. PAN (peroxy acetyl nitrate) concentrations are also sensitively affected by reactive fate of NOx and organics, especially acetaldehyde. HCHO, CH₃CHO, and PAN must be understood and simulated for current endeavors to predict daily and long-term variations in tropospheric ozone. (1) Empirical investigations of the massive INTEX-NA (2004) and NARE-97 datasets show compelling deviations of the real state of the atmosphere from its modeled state. Formaldehyde has outflow componentswhich are different and much broader than acetaldehyde. Careful multivariate analysis suggests that source-variety tracers for the aldehyde precursors explain ca. 94% of the variance. However, the observed strong co-variation of HCHO and haze aerosol (CN, bscat) is puzzling, and is not at all shared by CH₃CHO. The co-variation might indicate poorly known but strong aerosol-gas phase exchanges affecting the HCHO. However, we must first quantify more conventional explanations, e.g., that certain sources, perhaps widespread isoprene emissions, favor the simpler aldehyde. (2) Regional modeling of these aldehydes and PAN seem to indicate that the Carbon Bond and SPRC mechanisms, useful for more local modeling, actually "short-circuit" organic reactions to emphasize reactive products on the larger scale, producing distressingly high amounts of all three species, especially CH₃CHO. Global model mechanisms perform somewhat better.. We illustrate these ideas with results from versions of the UNC-Community Multiscale (CMAQ) model and the NASA Global Modeling Initiative tropospheric model applied to INTEX-NA and NARE-97 observations. (http://geo.arc.nasa.gov/sgg/chatfield/presentations.html)
DE: 0305 Aerosols and particles (0345, 4801, 4906)
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: Fall Meeting 2005