1 the asian aerosol contribution to north american pm pollution: recognizing asian transport...

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The Asian Aerosol Contribution to The Asian Aerosol Contribution to North American PM Pollution:North American PM Pollution:

Recognizing Asian TransportRecognizing Asian TransportComposition and ConcentrationComposition and Concentration

Modeling Regional Aerosol BurdensModeling Regional Aerosol Burdens

Richard “Tony” VanCurenCalifornia Air Resources Board

ICAP October 22, 2004

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MOPITT CO March-Dec. 2000 MOPITT CO March-Dec. 2000

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The April 1998 Asian Dust Storms: The April 1998 Asian Dust Storms: a Natural Experimenta Natural Experiment

Image after Husar, 2000

VanCuren & Cahill, 2002

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Asian Dust Frequency (% of days by month 1988-Asian Dust Frequency (% of days by month 1988-99)99)

Northeast Pacific BasinNortheast Pacific Basin


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Comparative Frequency and ConcentrationComparative Frequency and ConcentrationAsian Asian vsvs. African Dust in Eastern North . African Dust in Eastern North

AmericaAmerica

FREQUENCY CONCENTRATION|


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Composition of the Whole Asian Composition of the Whole Asian Plume:Plume:“Minimum Concentration” Hypothesis:• Lemma:

Asian pollutants in West are broadly distributed, and ~ equal;local pollutants are variable.

• Implications:Mean concentration = mean Asian + mean local concentrations. Lowest means imply least local pollutants - CRLA & LAVO.

Staged Analysis (Crater Lake & Lassen):• Selected Asian Days: First Approximation - composition

when Asian dust dominates and no local fires (low OC/S).• All Asian Days: Aerosol composition for all days with Asian

Dust - recognize local fire contribution.• All Days: Aerosol composition for all days in transport

season (March - October) - recognize local sources.

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Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

0.00.10.20.30.4

PC

1

ASIAN DUST & COMBUSTION 0.93

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

0.00.10.20.30.40.5


Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.10.00.10.20.30.4

CRLV_PCZ16_ALL


Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.4-0.2-0.00.2

PC

2

AGED SMOKE, REACTED SEA SALT 0.08

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.3-0.10.10.3


Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.5-0.3-0.10.10.3


Cl-

Na

Al

Ca

Fe Si

Ti H

OC

EC

Kn

on

Br

Pb

Zn

SO

4=

NO

3--0.3

-0.00.30.6

PC

3

SEA SALT, NO SMOKE -0.05

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on

Br

Pb

Zn

SO

4=

NO

3--0.6

-0.3-0.00.3

FRESH SMOKE, NO SEA SALT 0.16

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.6-0.4-0.2-0.00.20.4 FRESH SMOKE, DUST, NO SALT 0.09

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.5-0.3-0.10.10.30.50.7

PC

4

AGRICULTURAL SMOKE (RICE) -0.03

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.4-0.20.00.20.40.60.8

AGRICULTURAL SMOKE (RICE), SOIL DUST -0.03

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

-0.3-0.10.10.30.50.70.9

MOTOR VEHICLE, ROAD DUST 0.02

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

LOW SMOKEHIGH CONFIDENCE ASIAN DUST

-0.8-0.6-0.4-0.2-0.00.2

PC

5

AGRICULTURAL SMOKE (GRASS), SOIL DUST -0.06

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

ALL DAYSHIGH CONFIDENCE ASIAN DUST

-0.8-0.6-0.4-0.20.00.20.4

SOIL DUST, REACTED SEA SALT -0.09

Cl-

Na Al

Ca

Fe Si

Ti H

OC

EC

Kn

on Br

Pb

Zn

SO

4=

NO

3-

ALL DAYSMARCH - OCTOBER

-0.8-0.6-0.4-0.20.00.20.4

PC

6

SOIL DUST, SEA SALT -0.03

Generalizing - known events to all Generalizing - known events to all daysdays

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Regression-Derived Source & CompositionRegression-Derived Source & CompositionBreakdown for Crater Lake / Mt. Lassen AerosolBreakdown for Crater Lake / Mt. Lassen Aerosol

MEAN S.D. MEAN S.D. MEAN S.D. MEAN % S.D. %

TOTAL MASS (PM10) 6.7 3.9 6.7 5.1 7.4 6.2 DUSTY ASIAN PLUME 6.4 4.2 4.9 4.3 4.5 4.0 60 54

AGED SMOKE & SEA SALT 0.15 0.10 1.7 1.2 0.46 1.2 6 16FRESH SMOKE & LOCAL DUST 0.02 0.25 1.5 1.7 20 23

SEA SALT 0.02 0.26ROAD VEHICLE & DUST 0.17 0.50 2 7AGRICULTURAL SMOKE 0.06 0.88 0.01 0.45SEA SALT & SOIL DUST 0.04 0.67 0.93 0.93 13 13

COARSE MASS (PM10-2.5) 2.9 1.9 2.9 2.9 3.8 3.9 51 52 DUSTY ASIAN PLUME 2.9 1.9 2.8 2.4 1.9 2.0 25 27

AGED SMOKE & SEA SALT 0 0 0 0.10 0 0.45 0 6FRESH SMOKE & LOCAL DUST 0 0.15 1.2 1.4 16 18

SEA SALT 0.01 0.06ROAD VEHICLE & DUST 0.17 0.47 2 6AGRICULTURAL SMOKE 0.05 0.81 0.01 0.05SEA SALT & SOIL DUST 0.04 0.57 0.88 0.86 12 12

FINE MASS (PM2.5) 3.8 2.0 3.8 2.3 3.6 2.4 49 32 DUSTY ASIAN PLUME 3.5 2.3 2.1 2.0 2.6 2.0 35 27

AGED SMOKE & SEA SALT 0.15 0.10 1.7 1.1 0.46 0.74 6 10FRESH SMOKE & LOCAL DUST 0.02 0.10 0.26 0.39 4 5

SEA SALT 0.02 0.20ROAD VEHICLE & DUST 0 0.03 0 0AGRICULTURAL SMOKE 0.01 0.07 0 0.41 0.07 0.18SEA SALT & SOIL DUST 0 0.11 0.05 0.07 1 1

All Days March-October 1989-1999

Low Smoke C/SO4 < 4

No Large Local Fires C/SO4 < 6

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What is the temporal structure of Asian What is the temporal structure of Asian transport?transport?

• “SPRING” research model:– Based on data from Mauna Loa– Subsequent field studies have focused on spring

sampling

• “EPISODIC” research model:– A priori assumption based on experience with Asian

“Yellow Sand” dust storms– Bolstered by “mass = event” logic in studying Asian

outflow gas and aerosol chemistry and transport meteorology

– Reinforced by conservative receptor analyses (e.g. cluster analysis of 1998 dust storm)

• An unbiased measurement: – Continuous sampling during ITCT-2K2

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ITCT-2K2 Aerosol Measurement SitesITCT-2K2 Aerosol Measurement Sites

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Trinidad Head Aerosol Time Series - ITCT-2K2Trinidad Head Aerosol Time Series - ITCT-2K2

4/21 - 4/24

VanCuren et al., 2004

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Trinity Alps Aerosol Time Series - ITCT-2K2Trinity Alps Aerosol Time Series - ITCT-2K2

0

2000

4000

6000

8000

X-R

ay M

ass

ng /

m3

10 - 5 um5 - 2.5 um2.5 - 1.1 um1.1 - .75 um.75 - .54 um.54 - .34 um.34 - .24 um.24 - .09 um

Trinity

4/1

4/2

002

4/2

1/2

002

4/2

8/2

002

5/5

/2002

5/1

2/2

002

5/1

9/2

002-10

0

10

20

PC

Score

0

500

1000

1500

2000

2500

3000

ng /

m3

PC1Total ClTotal Si

4/21 - 4/24


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Mt. Lassen Aerosol Time Series - ITCT-2K2Mt. Lassen Aerosol Time Series - ITCT-2K2

0

2000

4000

6000

X-R

ay M

ass

ng

/ m

3

10 - 5 um5 - 2.5 um2.5 -1.1 um1.1 - .75 um.75 - .54 um.54 - .34 um.34 - .24 um.24 - .09 um

Lassen

4/1

4/2

002

4/2

1/2

002

4/2

8/2

002

5/5

/2002

5/1

2/2

002

5/1

9/2

002-10

0

10

20

PC

Sco

re

0

500

1000

1500

2000

2500

3000

ng

/ m

3

PC1Total ClTotal Si

4/21 - 4/24


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ConcordantConcordant Montane Montane Aerosol:Aerosol:

Single dominant aerosol

Asian origin confirmed by soil element profiles

Concentration varies but continuously present

0 2000 4000 6000 8000TOTAL X-RAY MASS ng

-10

-5

-0

510

1520

PC

1

LASSEN

0 2000 4000 6000 8000TOTAL X-RAY MASS ng

-10-5-05

101520

PC

1

TRINITY

4/14 4/21 4/28 5/5 5/12 5/19 5/26

-10

0

10

20

PC

Sco

re

LASSENTRINITY


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Asian aerosol persists even after rain Asian aerosol persists even after rain


Trinity Max

Lassen Max

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Observational FindingsObservational Findings

• Asian Continental Aerosol Plume is persistent over western North America; detectable Alaska to Virgin Islands

• Average concentration is about 5 g/m3 PM10• Mass median diameter is 2-3 m• Average PM2.5 concentration is about 3 g/m3 • 1/2 of coarse, 3/4 of fines at CRLA & LAVO• Approximately ¼ of the new annual California AAQS

for PM10 and PM2.5• Approximately 1/10 of the new Federal annual PM10

NAAQS; 1/5 of the annual PM2.5 NAAQS• Asian aerosols are the regional “clean” background

in much of North America

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Modeling Western U.S. PM Air QualityModeling Western U.S. PM Air QualityFailure Modes: Estimation Error and Process ErrorFailure Modes: Estimation Error and Process Error

YOSE SO4

PINN SO4

Expected uncertainty in regional models.

Systematic divergence between

model and reality.

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Process error may be widespread:Process error may be widespread:Colorado Plateau fine soilColorado Plateau fine soil

GRBA BRCA MOZI

BRCA GRCA CANY

WEMI MEVE GRSA

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Regional Aerosol Events are not Resolved by Regional Aerosol Events are not Resolved by CMAQ:CMAQ:

Feb 24, 1996 (Day 55)Feb 24, 1996 (Day 55)

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Regional Aerosol Chemistry:Regional Aerosol Chemistry:Feb 21 & 24, 1996Feb 21 & 24, 1996

RE

DW

1

PO

RE

1

CR

LA

1

MO

RA

1

TH

SI1

LA

VO

1

SN

PA

1

PIN

N1

CO

RI1

BL

IS1

SO

LA

1

YO

SE

1

SE

QU

1

SA

GO

1

DE

VA

1

JA

RB

1

SA

WT

1

GR

BA

1

SA

LM

1

GL

AC

1

CR

MO

1

SC

OV

1

BR

CA

1

GR

CA

1

ING

A1

LO

PE

1

TO

NT

1

SA

GU

1

YE

LL

1

CA

NY

1

BR

ID1

PE

FO

1

CH

IR1

ME

VE

1

GIL

A1

WE

MI1

WH

RI1

MO

ZI1

BA

ND

1

RO

MO

1

RO

MO

2

GR

SA

1

GU

MO

1

BIB

E1

BA

DL

1

0.1

1

10

100

1000

10000

100000

46

2346

2346

2346

2346

2346

23468

ng

/m3

MCMFIMPROVE_SOILSO4SEPB

2/24/962/21/96

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Uncertainties in Modeling Uncertainties in Modeling Asian Impact on U.S. PMAsian Impact on U.S. PM

• Asian Emissions - timing and location– Desert dust (Takla Makan & Gobi)– Anthropogenic dust (Loess Plateau)– Urban / Industrial / Transportation Sources

• Global Transport - meteorology and process– Spatial resolution– Aerosol processing

• N.A. Regional Transport - emissions and meteorology– Source location and activity– Wind fields– Rough terrain

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ConclusionsConclusions

• Asian aerosol is a dominant component of the “regional background” for rural PM in the Western U.S.

• The Asian “background” concentration is highly variable.

• Parsing the Asian aerosol flux into an “Airshed” model requires more than setting “boundary conditions.”

• Past contributions of Asian PM are a source of significant error in retrospective modeling.

• Projections of future “background” PM must include scenarios for Asian economic growth and evolving emission control programs.

1 the asian aerosol contribution to north american pm pollution: recognizing asian transport...

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