Sources and Atmospheric Processing of FineParticles from Asia and the NorthwesternUnited States Measured During INTEX-B

Peltier, R., Hecobian, A., Weber, R.1

Stohl, A2

Atlas, E., Riemer, D. 3

Blake, D.4

Apel, E., Campos, T., Karl, T. 51Georgia Tech, 2Norwegian Institute for Air Research, 3University of Miami,4UC Irvine, 5NCAR

Funded by NASAPaper available at: http://www.atmos-chem-phys-discuss.net/papers_in_open_discussion.html

Outline/Methods• INTEX-B C-130 PM1 Results

– Asian vs North American air masses• SO4

= and WSOC average concentrations• WSOC/SO4

= 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; PM1 particles captured in water– Soluble anions and cations by IC (SO4

=)– Water-soluble Organic Carbon (WSOC) by TOC analysis

INTEX-B: NSF C-130 Flights

60°

55

50

45

40

35

30

-160° -140 -120 -100

NSF C-130 Intex-B April/May 2006

April 21 to May 15, 2006 Altitude Range: ~ 0.1 to 7.3 km asl.10 Flights out of Everett WA

Asia vs N.American InfluenceUsing 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%

60°

50

40

30

-140° -120 -100 -80 -60 -40

NSF C-130 Intex-B April/May 2006

NOAA P-3 ICARTT July/Aug. 2004

INTEX-B vs ICARTT

0.80.40.6SO4=

0.90.20.3WSOC

NAAsiaAll

4.0SO4=

1.6WSOC

AllMedianConcentrations

MedianConcentrations

x 5

x 7

x 5x 2

µgC/m3

µg/m3

Comparison of Fine OA/SO4= Alt. Profiles

In many regions,free trop. particulateOA is greater thanSO4

= mass.

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

0.12 3 4 5 6 7

12 3 4 5 6 7

10

WSOC versus Sulfate (gC/gSO42-)

* From Heald et al. 2005

NEAQS

North-eastern U.S.A.

ACE ASIA OCEastern Asia*

Median ratio of binned data

ICARTT or

Observed earlier inEastern U.S.,Novakov et al, JGR1997.

Comparison of Fine OA/SO4= Alt. Profiles

In many regions,free trop. particulateOA is greater thanSO4

= mass.

In Asian air masses,recorded from C-130during INTEX-B,free trop. depleted inOA wrt SO4

=.

Asian FT air mass dominated by SO4=

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

0.12 3 4 5 6 7

12 3 4 5 6 7

10

WSOC versus Sulfate (gC/gSO42-)

* From Heald et al. 2005

INTEX-B

NEAQS

Asian AirIn Western U.S.A

North-eastern U.S.A.

ACE ASIA OCEastern Asia*

ICARTT or

Why is INTEX-B Asian Altitude Profile Different

• SO4= reformed in route, some SO2 penetrates precip.

• OA not reformed- SOA precursors scavenged and/or depleted prior to precip., and no sig. source

over ocean.

SecondaryProduction

PrecipitationScavenging

OA & SO4= Lost in Precip. near Asia

INTEX-B:Northwestern U.S. free trop.OA enhanced wrt SO4

=.

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

0.12 3 4 5 6 7

12 3 4 5 6 7

10

WSOC versus Sulfate (gC/gSO42-)

* From Heald et al. 2005

INTEX-B

NEAQS

North-western U.S.A.

Asian AirIn Western U.S.A

North-eastern U.S.A.

ACE ASIA OCEastern Asia*

What is Source for FT Organic Aerosol?

6000

5000

4000

3000

2000

1000

Alti

tude

, m

1.61.20.80.4Median WSOC, µgC/m3

2147

8082

7556

5727

503318

2832

2312

12 INTEX-BN. America

Region of high organic aerosolconcentrations measured in FTover Northern Nevada (alt ~ 4 km)

ICARTT or

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2WS

OC

(µgC

m-3)

1201101009080

CO (ppbv)

INTEX-B CloudSlope: 0.052r2 = 0.59 Eastern

U.S.

• Possible California CentralValley & coastal urban areas

• WSOC somewhat correlatedwith CO

• ΔWSOC/ΔCO higher than otherstudies

42

40

38

36

34

32

-124 -120 -116 -112

70

60

50

40

30

20

10

0

ΔW

SOC/ΔCO

, µgC

m-3

ppm

v-1

140120100806040200

Photochemical age, hr

250

200

150

100

50

0

Toluene, pptv

NYC de Gouw et al. NYC Sullivan et al. Fit to NYC de Gouw et al.

Atlanta surface North GeorgiaINTEX-B

What is Source for N.A. FT Organic Aerosol?

Average urban Eastern U.S. clear skySOA production ~ 34 µgC/m3/ppmv(de Gouw et al. 2007)

Sunglint

Convective Clouds

42

40

38

36

34

32

-124 -120 -116 -112

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2WSO

C (µ

gC m

-3)

76543210

Water vapor (g kg-1)

Slope: 0.33 ± 0.03Int: 0.19 ± 0.10r2 = 0.80

Enhanced Free Trop. WSOCIs In Region of Cloud Outflow MODIS (Aqua) AOD/COT observed

between 21:25Z and 21:35Z

Satellite images provided by Chieko Kittaka• Aircraft videoshows cloudyregion

• Back trajectoriesthru clouds

• WSOC - H2Ovcorrelated

WSOC Biogenic/Anthropogenic byMultivariate Analysis

WSOCpred = B0 + B1x1 + B2x2 + Σ Bixi

Biogenic vs Anthropogenic (FF) influence by sum of |Ba| versus |Bb|

Independent Variables (xi) as Source Tracers

[VOC]'s normalized.Allows direct comparisonsbetween Bi.

Fossil Fuel VOCs Biogenic VOCs1,1,1-trichloroethane Methyl chlorideMethylethylketone MethanolIsopentane HydroxyacetonePentane AcetonitrileButane IsopreneAcetaldehyde AcetoneIsobutane Acetic AcidTolueneBenzeneMethyl tertiary butyl etherIsopropyl nitrateo-xylenen-pentane

0

20

40

60

80

100

Biogenic Anthropogenic

Frac

tion

Biog

enic/

Anth

ropo

geni

c Co

effic

ient

Sum

Asia N.America

CloudProcessed

r2 49% 76% 93%Percent observedWSOC variabilityexplained by model

Plumeover

Nevada

OnlyAcetonitrile

WSOC Biogenic/Anthropogenic WSOC byMultivariate Analysis For INTEX-B Data

• Asian: WSOC mostlyassociated with anthro.VOCs, some BB

• N. American 50/50

• Cloud processed 2/3biogenic VOCs

Summary: INTEX-B C-130• In Asian air masses reaching N. America:

– PM1 SO4= and OA concentrations are low < 1 µg/m3

– Role of precip. scavenging during transport results in?• PM1 Free Trop. OA < SO4

=

• Unlike SO4=, anthrop. OA not regenerated far from source.

• North American (continental) air masses:– Free Trop. OA > SO4

=

– Evidence for cloud processing as a source for PM1 FT OA,and mainly associated with biogenic VOCs

Paper available at: http://www.atmos-chem-phys-discuss.net/papers_in_open_discussion.html