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Aerosol Measurements from the C-130

Aerosol Measurements from the C-130. Edward Dunlea, Peter DeCarlo, Jose-Luis Jimenez University of Colorado INTEX-B Meeting 3/6/2007. Size distribution. Mass spectrum. dM/dLogDp. Diameter (nm). Speciated Time Series. Aerosol Mass Spectrometer (AMS). Available on FTP site.

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Aerosol Measurements from the C-130

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  1. Aerosol Measurements from the C-130 Edward Dunlea, Peter DeCarlo, Jose-Luis Jimenez University of Colorado INTEX-B Meeting 3/6/2007

  2. Size distribution Mass spectrum dM/dLogDp Diameter (nm) Speciated Time Series Aerosol Mass Spectrometer (AMS) Available on FTP site Aerosol Sampling AMS Concentration 1 hr of INTEX flight Available on request Available on request Composition Size-resolved composition

  3. 5/1/2006 Flight AMS observes high SO4 loading with some Organics E.Apel et al. (TOGA)  MTBE as tracer for Asian pollution MTBE used in gasoline in Asia, no longer in U.S. gas This appears to be best Asian transport event

  4. Possible Explanation #1 – Processing Organic Aerosol Org / SO4 Org / SO4 SOA Precursor Sulfate Aerosol Scavenging Event SO2 Concentration Idea proposed by Brock et al., 2004 ITCT-2k2 campaign ~ 1-2 days ~ 1 week Time • Organic precursors form organic aerosol faster than SO2 SO4 • Scavenging event removes particulate matter • Relatively more SO2 left to form new SO4 • Scavenging event = uplift through a cloud • Method by which most (all?) Asian air transported across Pacific

  5. Possible Explanation #2 – Source Region • Takami et al., Atm. Env., 2005 • AMS Sampling on Fukue Island • Downwind of China and Korea/Japan • Organics observed in similar levels from both directions • Sulfate much higher from China • Organic / SO4 ratio • RatioChina << RatioK/J • Could source region being high in SO4 be reason for high SO4 on other side of Pacific? From Takami et al., 2005

  6. 5/1/2006 Flight (RF 06) • Pre-flight modeling showed Asian influenced air mass off coast of Northwest U.S. • Flight plan chosen to intercept it • Pollution seen in layer at 20,000 ft early and late in flight

  7. Organics vs CO in Asian Plumes 5/1/06

  8. Organics vs CO, all IMPEX over ocean

  9. Model-Measurement Comparisons GEOS-CHEM vs AMS For all flights Sulfate Modeled vs Measured values fall around 1:1 line Organics Modeled vs Measured values fall well below 1:1 line

  10. Model-Measurement Comparisons – (cont.) Heald et al. Only data over ocean Observed Simulated Previous study over Western Pacific  Large discrepancy (> ×10) INTEX: GEOS-CHEM under predicts Organics by smaller amount (×3) MOZART under predicts Sulfate

  11. Conclusions • Aerosol instruments on C-130 compare well • High sulfate observed in transported Asian pollution • Processing vs Source Region Emissions • 5/1/2006 flight = best Asian transport event • Comparisons with models show better agreement for organics than previous studies • Next steps: • Further work on 5/1/2006 flight • Further comparisons with models • Good metrics for cloud processing?? • Further work on organic fraction of aerosol • Positive Matrix Factorization • High-Resolution AMS data Thanks to C-130 crew & scientists; NASA support team; NOAA collaborators; NASA, NSF & UCAR ($)

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