CANADIAN, MEXICAN, AND INTERCONTINENTAL CANADIAN, MEXICAN, AND INTERCONTINENTAL INFLUENCES ON U.S. AIR QUALITYINFLUENCES ON U.S. AIR QUALITY

Daniel J. Jacob

with Rokjin J. Park1, Helen Wang, Philippe H. LeSager, Lin Zhang

and funding from EPRI, DOE, NASA

1 now at Seoul National University

THE U.S. EPA REGIONAL HAZE RULETHE U.S. EPA REGIONAL HAZE RULE

Mean visibility degradation (deciviews) at IMPROVE sites, 2001

Reduce U.S. aerosol sources to improve visibility in wilderness areas: progress must follow a linear rate toward endpoint of natural visibility by 2064

Park et al. [AE 2006]

1ox1o

NATURAL vs. BACKGROUND VISIBILITY DEGRADATIONNATURAL vs. BACKGROUND VISIBILITY DEGRADATION

Deciviews

2001 observations Natural Background; includestransboundary pollution

g m-3

Natural: shut off anthropogenic emissions worldwideBackground: shut off anthropogenic emissions in U.S. only

Park et al. [AE 2006]

>70% of transboundarypollution is from Canada and Mexico

Modelsimulations

DIFFERENT DEFINITIONS OF THE U.S. OZONE BACKGROUNDDIFFERENT DEFINITIONS OF THE U.S. OZONE BACKGROUND

GEOS-Chem 1ox1o simulationAll slides show max daily 8-h surface ozone for June-August 2001

N. American backgroundZero anthropogenicemissions in N. AmericaUsed by EPA as policy-relevant background (PRB)

U.S. backgroundZero anthropogenicemissions in U.S. only

Wang et al. [AE, submitted]

Mean JJA values

CANADIAN/MEXICAN OZONE POLLUTION ENHANCEMENTCANADIAN/MEXICAN OZONE POLLUTION ENHANCEMENT

as computed by difference of N. American and U.S. backgrounds

Circles are CASTNET/AQS rural sites used for model evaluation

Mean Canadian/Mexican enhancements are 1-3 ppb over most of U.S.; much larger enhancements in border areas of Northeast (up to 15 ppb), Southwest (up to 13 ppb)

Canadian emissions from CAC (2005), Mexican emissions from BRAVO (1999)

Wang et al. [AE, submitted]

Mean June-August 2001 values (months when Can/Mex influence is maximum)

Boersma et al. [JGR 2008]

TROPOSPHERIC NOTROPOSPHERIC NO22 FROM OMI FROM OMI

October 2004

U.S.

NEI 99

Canada

CAC 05

Mexico

BRAVO 99

Anthropogenic NOx

emissions Tg N a-1

6.7 0.76 0.93

Most Canadian emissions areclose to U.S. border: not so for Mexico

MODEL EVALUATION FOR CANADIAN/MEXICAN INFLUENCEMODEL EVALUATION FOR CANADIAN/MEXICAN INFLUENCETime series at the sites most affected

Ozo

ne,

pp

b

Jun Jul Aug

Whiteface Mtn. Base, NY

ObservationsModel (standard)

observed O3 >75 ppb with >10 ppb from Canada/Mexico

Wang et al. [AE, submitted]

US backgroundNA background (PRB)Canada + Mexico

Unionville, MichiganAlpine, California

BACKGROUND CORRELATION WITH OZONEBACKGROUND CORRELATION WITH OZONEBackground concentration statistics for NE and SW sites in 10-ppb ozone bins

max75th

med

25th

min

North American background U.S. background 1:1 model vs. obs. line

Wang et al. [AE, submitted]

An air quality standard as low as 60 ppb would be achievable with domestic emission reductions alone

Northeast

Southwest

AREAS WHERE CANADIAN/MEXICAN INFLUENCES CONTRIBUTE MOST AREAS WHERE CANADIAN/MEXICAN INFLUENCES CONTRIBUTE MOST TO EXCEEDANCES OF U.S. AIR QUALITY STANDARDTO EXCEEDANCES OF U.S. AIR QUALITY STANDARD

# model days in JJA 2001 where ozone >75 ppb and Can/Mex influence > 10 ppb

Largest effects around the Great Lakes, eastern seaboard, and S. California

Wang et al. [AE, submitted]

LOOKING AHEAD TO 2020LOOKING AHEAD TO 2020Global CLE inventory + CAIR for U.S.

Anthropogenic NOx emissions by 51% in U.S., 49% in Canada, 34% in Mexico …but CLE inventory has high emissions in southeastern Canada!

Canadian pollution influence in Northeast U.S. in 2020 is comparable to or greater than residual influence from U.S. power plants (18% of U.S. NOx emissions in 2020)

Summer mean Canadian/Mexicanpollution enhancement (2020)

Wang et al. [AE, submitted]

NASA/INTEX-B AIRCRAFT CAMPAIGN (APR-MAY 2006)NASA/INTEX-B AIRCRAFT CAMPAIGN (APR-MAY 2006)

Validate, augment, and exploit satellite observations of transpacific transport

DC-8

C-130

Honolulu

Anchorage

Seattle

TES and AIRS satellite observations of a transpacific plumeCO columnsTES GEOS-Chem AIRS

Zhang et al. [ACP, submitted]

DC-8track

A

B

USING OZONE-CO CORRELATIONS FROM TES USING OZONE-CO CORRELATIONS FROM TES TO DETECT TRANSPACIFIC OZONE POLLUTIONTO DETECT TRANSPACIFIC OZONE POLLUTION

Zhang et al. [ACP, submitted]

Transpacific Plume observed by DC-8 on May 9th

B-south branch

HNO3NO

O3CO

Solid: observationsDash: GEOS-Chem

A-north branch

PAN

COO3

PAN

Backward and forward trajectories for the plume

• Ozone is produced in the S-branchfollowing subsidence and decomposition of PAN to NOx

• Most of this ozone circles around the Pacific High and becomes the “river of pollution” to the western equatorial Pacific (PEM-Tropics B); only a small fraction reaches the western U.S.

A

B

“river ofpollution”

Zhang et al. [ACP, submitted]

SOURCE ATTRIBUTION OF OZONE USING MODEL ADJOINTSSOURCE ATTRIBUTION OF OZONE USING MODEL ADJOINTSGEOS-Chem adjoint simulation for INTEX- B period (Apr-May 2006)

Contribution of ozone production regions to ozone concentration at Mt. Batchelor Observatory

23% 21%17%

6%6%

Mean East Asian pollution enhancement of 9.2 ppb at MBO includes 5.6 ppb from China and 3.6 ppb from Japan+Korea

Zhang et al. [in prep.]