Sources and Atmospheric Processing of Fine Particles from Asia and the Northwestern United States Measured During INTEX-B

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1 Sources and Atmospheric Processing of Fine Particles from Asia and the Northwestern United States Measured During INTEX-B Peltier, R., Hecobian, A., Weber, R. 1 Stohl, A 2 Atlas, E., Riemer, D. 3 Blake, D. 4 Apel, E., Campos, T., Karl, T. 5 1 Georgia Tech, 2 Norwegian Institute for Air Research, 3 University of Miami, 4 UC Irvine, 5 NCAR Funded by NASA Paper available at:

2 Outline/Methods INTEX-B C-130 PM 1 Results Asian vs North American air masses SO 4 and WSOC average concentrations WSOC/SO 4 vertical profiles Source for Free Trop. Organic Aerosol INTEX-B Eg; WSOC in region of cloud detrainment WSOC vs Biogenic/Anthrop. VOCs, multiple regression results Methods: PILS; PM 1 particles captured in water Soluble anions and cations by IC (SO 4 ) Water-soluble Organic Carbon (WSOC) by TOC analysis

3 INTEX-B: NSF C-130 Flights April 21 to May 15, 2006 Altitude Range: ~ 0.1 to 7.3 km asl. 10 Flights out of Everett WA NSF C-130 Intex-B April/May

Asia vs N. American Influence Using Flexpart CO E.g., Predominant North American Influence E.g., Predominant Asian Influence Flexpart CO: Emissions Only Asian CO: >75% Asian 48%, n 2931 N.

4 Asia vs N. American Influence Using Flexpart CO E.g., Predominant North American Influence E.g., Predominant Asian Influence Flexpart CO: Emissions Only Asian CO: >75% Asian 48%, n 2931 N. American CO: > 75% NA. 12%, n 704 Remainder: 40% not clear which dominated Asian and N.A. Flexpart CO>100ppbv ~ 95%

5 INTEX-B vs ICARTT NSF C-130 Intex-B April/May Median Concentrations µgc/m3 WSOC µg/m3 SO4 NOAA P-3 ICARTT July/Aug All Asia NA x x Median Concentrations WSOC SO4-40 All 1.6 x x 7

6 Comparison of Fine OA/SO 4 Alt. Profiles Median ratio of binned data Altitude (m) NEAQS ACE ASIA OC Eastern Asia* ICARTT or Northeastern U.S.A. * From Heald et al In many regions, free trop. particulate OA is greater than SO 4 mass. Observed earlier in Eastern U.S., Novakov et al, JGR WSOC versus Sulfate (gc/gso 4 2- )

7 Comparison of Fine OA/SO 4 Alt. Profiles Asian FT air mass dominated by SO 4 Altitude (m) INTEX-B Asian Air In Western U.S.A NEAQS ACE ASIA OC Eastern Asia* ICARTT or Northeastern U.S.A. * From Heald et al In many regions, free trop. particulate OA is greater than SO 4 mass. In Asian air masses, recorded from C-130 during INTEX-B, free trop. depleted in OA wrt SO WSOC versus Sulfate (gc/gso 4 2- )

8 Why is INTEX-B Asian Altitude Profile Different OA & SO 4 Lost in Precip. near Asia Precipitation Scavenging Secondary Production SO 4 reformed in route, some SO 2 penetrates precip. OA not reformed - SOA precursors scavenged and/or depleted prior to precip., and no sig. source over ocean.

9 What is Source for FT Organic Aerosol? INTEX-B: Northwestern U.S. free trop. OA enhanced wrt SO 4. Region of high organic aerosol concentrations measured in FT over Northern Nevada (alt ~ 4 km) Altitude (m) INTEX-B Asian Air In Western U.S.A Northwestern U.S.A ICARTT or NEAQS ACE ASIA OC Eastern Asia* * From Heald et al Northeastern U.S.A. WSOC versus Sulfate (gc/gso 4 2- ) 10 Altitude, m INTEX-B N. America Median WSOC, µgc/m

10 What is Source for N.A. FT Organic Aerosol? WSOC (µgc m -3 ) INTEX-B Cloud Slope: r CO (ppbv) 110 Eastern U.S. 120 ΔWSOC/ΔCO, µgc m -3 ppmv Atlanta surface North Georgia INTEX-B Photochemical age, hr Toluene, pptv NYC de Gouw et al. NYC Sullivan et al. Fit to NYC de Gouw et al. 140 Average urban Eastern U.S. clear sky SOA production ~ 34 µgc/m 3 /ppmv (de Gouw et al. 2007) Possible California Central Valley & coastal urban areas WSOC somewhat correlated with CO ΔWSOC/ΔCO higher than other studies

observed between 21:25Z and 21:35Z Satellite images provided by Chieko Kittaka Back trajectories thru clouds

11 Enhanced Free Trop. WSOC Is In Region of Cloud Outflow Convective Clouds Aircraft video shows cloudy region MODIS (Aqua) AOD/COT observed between 21:25Z and 21:35Z Satellite images provided by Chieko Kittaka Back trajectories thru clouds WSOC - H2Ov correlated -3 WSOC (µgc m ) Sunglint Slope: 0.33 ± 0.03 Int: 0.19 ± r Water vapor (g kg )

12 WSOC Biogenic/Anthropogenic by Multivariate Analysis WSOC pred B 0 + B 1 x 1 + B 2 x 2 + Σ B i x i Independent Variables (x i ) as Source Tracers Fossil Fuel VOCs 1,1,1-trichloroethane Methylethylketone Isopentane Pentane Butane Acetaldehyde Isobutane Toluene Benzene Methyl tertiary butyl ether Isopropyl nitrate o-xylene n-pentane Biogenic VOCs Methyl chloride Methanol Hydroxyacetone Acetonitrile Isoprene Acetone Acetic Acid [VOC]'s normalized. Allows direct comparisons between B i. Biogenic vs Anthropogenic (FF) influence by sum of B a versus B b

13 WSOC Biogenic/Anthropogenic WSOC by Multivariate Analysis For INTEX-B Data Fraction Biogenic/Anthropogenic Coefficient Sum Biogenic Asia N. America Anthropogenic r 2 49% 76% 93% Only Acetonitrile Plume over Nevada Cloud Processed Percent observed WSOC variability explained by model Asian: WSOC mostly associated with anthro. VOCs, some BB N. American 50/50 Cloud processed 2/3 biogenic VOCs

14 Summary: INTEX-B C-130 In Asian air masses reaching N. America: PM 1 SO 4 and OA concentrations are low < 1 µg/m 3 Role of precip. scavenging during transport results in? PM 1 Free Trop. OA < SO 4 Unlike SO 4, anthrop. OA not regenerated far from source. North American (continental) air masses: Free Trop. OA > SO 4 Evidence for cloud processing as a source for PM 1 FT OA, and mainly associated with biogenic VOCs Paper available at:

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