OZONE AND ITS PRECURSORS OVER THE UNITED STATES:

SOURCES, OUTFLOW, TRANSPACIFIC INFLOW, AND HEMISPHERIC INFLUENCE

Rynda Hudman

Advisor: Daniel Jacob April 6, 2007

INTEX-B mission Houston, March 2006

Biomass burning

Keeping ourselves in a job (Rob and Rama doing their part)

CONTINENT 2 OCEANCONTINENT 1

Intercontinental Influence of Ozone (1) primary constituent of smog in surface air [NRC, 1991]

(2) 3rd most important greenhouse gas [IPCC, 2001]

OH HO2

VOCs

NONO2

h

Hemispheric Pollution

Direct Intercontinental Transport(1 week)

Air quality

Greenhouse gas

4

8

2

Alt (km)

10

6

Air quality

O3

NORTH AMERICA : at midlatitudes we are all in each others tailpipe

• Background ozone• Transpacific transport

• Local surface production• Convection/Lightning

• Export• Transatlantic Transport

IN OUT

CO is used as a tracer of pollution

My work focuses on

CO column GMAO Forecast Friday, 4/20/06 - Mon, 4/24/06

RISING OZONE BACKGROUND AT NORTHERN MID-LATITUDES

Mountain sites in Europe1870-1990

Marenco et al. [1994] Jaffe et al. [2003]

U.S. Pacific coastal sites1985-2002

What is North American impact on ozone from biomass burning, fossil fuels, and lightning?

N. America

SENSITIVITY OF SIMULATED SURFACE OZONE TO ANTHROPOGENIC EMISSIONS IN INDIVIDUAL CONTINENTS

Europe

Asia

[Li et al., 2002]

Sept 1997

RegionalPollution

Ozo

ne

(pp

bv

)

Cumulative Probability

Low-elevation CASTNet sites, Jun-Aug

CASTNet observationsGEOS-Chem modelModel background

*

DEPLETION OF OZONE BACKGROUND DURING REGIONAL POLLUTION EPISODES

How much does Asian pollution affect ozone air quality in the United States?

Fiore et al., [2002]

1. INFLOW: How is ozone produced during transpacific transport of Asian pollution, and what are the implications for surface ozone air quality in the U.S.?

2. SOURCES and CHEMICAL EVOLUTION: How well constrained are U.S. CO and NOx sources from combustion and lightning? Can we relate the trend in the ozone-CO relationship in the U.S. boundary layer outflow to changes in OPE and emissions?

3. OUTFLOW AND INFLUENCE: How does NOx evolve in the U.S. boundary layer and what are the implications for NOx export? What is the impact of NA biomass burning, lightning and anthropogenic export on hemispheric ozone?

RESEARCH Questions:

TOOL: GEOS-CHEM: 3-D coupled ozone-NOx-VOC-aerosol tropospheric Chemistry Model [Bey et al., 2001] (uses assim. met.; 2ºx2.5º horiz. resn., 43 tracers) to interpret aircraft observations of ozone and its precursors

SOURCES, OUTFLOW, TRANSPACIFIC INFLOW, AND HEMISPHERIC INFLUENCE

North America

Subsidence Over E Pacific

PANNOxHNO3

strong O3

X10 Dilution

Asian Plume

Asia

Europe

INFLOW

MAJOR FINDINGS

NOx stationary sources 22%

Anthropogenic CO 60%

4

2

6

8

Alt (km)

10

O3 (ppbv)

SOURCES AND EXPORT

BB NA FF Lightning

NOx/flash4X larger than previously thought!

Export well constrained

effects on O3 & OPE

SUMMERSPRING

North America Asia

Europe

MAJOR FINDINGS (2)

North American (NA) enhancement to Northern Hemisphere summertime ozone burden

Northern Hemisphere Burden

2004 NA Biomass burning enhanced ozone 2-6 ppbv over Europe!

NOAA/ITCT-2K2 AIRCRAFT CAMPAIGN IN APRIL-MAY 2002 Monterey, CA

High-ozone Asian pollution plumes observed in lower free troposphere but not at surface (Trinidad Head)

CO

O3

PANHNO3

May 5 plume at 6 km:High CO and PAN,no O3 enhancement

May 17 subsidingplume at 2.5 km:High CO and O3,PANNOxHNO3

Hudman et al. [2004]

T. Ryerson (O3, NOx), John Holloway (CO), Frank Flocke (PAN), Andy Neuman (HNO3)Measurements (NOAA WP-3D):

CONCEPTUAL PICTURE OF OZONE PRODUCTIONIN TRANSPACIFIC ASIAN POLLUTION PLUMES

NOx

HNO3

PANAsianboundarylayer(OPE ~ 5)

PAN, weak O3

Warm conveyor belt; 5-10% export of NOy mainly as PAN

strong O3

Subsidence Over E Pacific

Gross OPE 60-80, low OH

PANNOxHNO3

U.S.boundarylayer very weak O3

10x dilution(Asian dust data)

E. Asia Pacific United States

Hudman et al. [2004]

Stratosphericdownwelling

GEOS-CHEM

Hudman et al. [2004]

CALIFORNIA MOUNTAIN SITES ARE PARTICULARLY SENSITIVE TO ASIAN OZONE POLLUTION

Observed 8-h ozone at Sequoia National Park (1800 m) in May 2002vs. corresponding simulated (GEOS-CHEM) Asian pollution ozone enhancement

Asian enhancements are 7-10 ppbvduring NAAQS exceedances;unlike at surface sites, Asian pollution influence is not minimum under high-ozone conditions!

May 17 obs. Asian plume event in red

Hudman et al. [2004]

ICARTT: COORDINATED ATMOSPHERIC CHEMISTRY CAMPAIGN OVER EASTERN NORTH AMERICA AND

NORTH ATLANTIC IN SUMMER 2004

SCIENTIFIC OBJECTIVES

• Regional Air Quality• Continental Outflow • Transatlantic Pollution • Aerosol Radiative Forcing

Biomass burning 2004Persistent Alaskan and Canadian burning

Canadian National Forest Fire Situation Report Sept 8, 2004 (http://www.nrcan.gc.ca/cfs-scf/redirects/fire/)

Wildfires in Alaska: > 2,500,000 Hectares!

Alaska Fire services: “The largest fire season in Alaska’s rich history ”

Biomass burning inventory created using MODIS hotspots and daily area burned

Canada

[Turquety et al., 2007]

CO June – August 2004

[Wallace McMillan]

May-August 2004 NA Fire Inventory

[Turquety et. al, 2007]

EPA National Emissions Inventory 1999 v1 (w/ modifications to VOCs) Power plant and Industry NOx 50%Anthropogenic CO 60%

GEOS-CHEM SIMULATION

NOx Lightning EmissionsLightning X4 over U.S.

& distributed to tropopause [Price and Rind, 1992]

Modifications from ICARTT constraints in blue (improved)

Flash counts (flashes/km2/s)

CO emissions

NOx

emission

GEOS-CHEM VS. ICARTT Mean comparison along the flight tracks

Large UT NOx bias

BL bias in CO and NOx

Ozone FT bias 5-10 ppbv

Measurements (WP-3D, DC-8): CO (J. Holloway, G. Sachse), NOx (T. Ryerson, R. Cohen, W. Brune), PAN (F. Flocke, H. Singh), HNO3 (A. Neuman, J. Dibb), ozone (T. Ryerson, M. Avery)

Observed Simulated Improved Simulation

DC-8 Midwest

Model / Observed NOx (0-2 km)

Hudman et al. [2007a,b]

[ratio]

Large overestimate powerplant/industry dominated Midwest and in the South

50% reduction in power and industry source as determined by Frost et al., [2006] improves boundary layer NO2 simulation

ICARTT OBSERVATIONS CONFIRM LARGE DECREASE SINCE 1999 IN INDUSTRY/POWER SOURCE

Measurements (WP-3D, DC-8): T. Ryerson (NO2), Ron Cohen/Tim Bertram (NO2)

OZONE REDUCTIONS RESULTING FROM DECREASE IN NOx EMISSIONS

Can we see changes in OPE due NOx emission reductions in dO3/dCO in U.S. outflow?

Requires good estimate of CO source…..

ECO

ENOOPE

dCO

dO x3

Regional differences in ozone, can be explained by OPE:

OPE

Midwest: 2.5-3.5

Southeast: 4-5.5

Hudman et al. [2007b]

Measurments: J. Holloway, G. Sachse, A. Goldstein

BOTH AIRCRAFT AND SURFACE DATA SUGGEST NEI 99 CO EMISSIONS ARE 2.5 TIMES TOO HIGH

Air

craf

t (0

-1.5

km

)C

heb

og

ue

Po

int

(su

rfac

e)

OBSERVED SIMULATED (NEI99) SIMULATED (anthro CO reduced by 60%)

Measurments:

J. Holloway, G. Sachse

Measurments: A. Goldstein/ Dylan Millet

Hudman et al. [2007b]

SCATTERPLOT OF SIMULATED TO OBSERVED CO

Parrish [2006] finds on-road source overestimated by 50% in NEI 99 (~33% reduction in NEI source)

CO decrease trend 3.7% yr-1 (1987-2002), (12% reduction in NEI source since 1999)

This estimate 2004 emissions 45% lower than NEI 99Hudman et al. [2007b]

ANTHROPOGENIC CO SOURCE IN THE UNITED STATES IN SUMMER IS NOW LOWER THAN BIOGENIC SOURCE

CO ANTHROPOGENIC EMISSION (11.5, 4.6)CO SOURCE FROM ANTHROPOGENIC VOC OXIDATION (1.8, 1.8)CO SOURCE FROM ISOPRENE OXIDATION (6.7, 6.7)CO SOURCE FROM OTHER BIOGENIC OXIDATION (2.4, 2.4)

NEI 99 NEI 99 with 60% reduction in CO

51%

10%

30%

8%

<1%

CO SOURCE FROM OTHER BIOMASS BURNING OVER CONTINENTAL U.S.(0.16, 0.16) Note: Fires in Canada and Alaska ~19 Tg CO

SOURCE TYPE (Tg CO)

30%

11%43%

15%

1%

OZONE-CO CORRELATIONS SHOW DECADAL INCREASE

ObservationsSlope = 0.47 +/- 0.01R2 = 0.54SimulationSlope = 0.36 +/- 0.02R2 = 0.21

ObservationsSlope = 0.41 +/- 0.03R2 = 0.47SimulationSlope = 0.34 +/- 0.03R2 = 0.17

50 100 150 200 250 300 50 100 150 200 250 3000

20

40

60

80

100

120

140

CO [ppbv] CO [ppbv]

O3 [

pp

bv]

Chebogue PointAircraft (0 - 1.5 km)

Obs during the early 90s show dO3/dCO ~ 0.3 – 0.4 [Chin et al., 1994; Parrish et al., 1998].

Change could be due to decadal changes in emissions

Overestimate of tropical background

WINDS FROM W-SE

ALL WIND DIRECTIONS

Aircraft (0-1.5 km, 11-5pm LT) Chebogue Point

Hudman et al. [2007b]

OBSERVED dO3/dCO INCREASE OVER THE PAST DECADE CONSISTENT WITH UNDERSTANDING OF OPE AND SOURCES

dO3/dCO OPE (dO3/dNOx) * NOx/CO source ratio (dNOx/dCO)

Consider NE U.S.,

July 1 – August 15, 2004 (With ICARTT Constraints)

Anthro = 1.2 Tg CO, 0.10 Tg N Biogenic = 0.87 Tg CO

July 1 – August 1994

4.9% anthro decrease/year in urban air [Parrish, 2006] Total CO 26% higher

22% stationary NOx reduction [Hudman et al., 2007] Anthro NOx 15% higher

OPE lower by ~9%

NOx/CO source ratio lower by ~19%

~28% increase in dO3/dCO expected 0.3-0.4 (90s) 0.4-0.5 (present)

Multiply dO3/dCO * ECO 1.5 Gmol ozone d-1

(Ozone flux consistent with 1990s estimates)

SPECIATION AND EXPORT OF BOUNDARY LAYER NOx

Hudman et al. [2007a]

We find observed f = 16 10% and modeled f = 14 9% (2.5-6.5km)

Model successfully simulates boundary layer NOy

yNOf R

CO

OBSERVED GEOS-Chem

NO

xH

NO

3P

AN

f= export efficiencyR = ECOanthro/ENOxanthro

= NMVOC CO production

Export to the lower free troposphere is mostly HNO3 but at higher altitudes is mostly PAN.

18% 7%

20% 9%

62% 84%

Offshore %Onshore %

UT NOx OBSERVATIONS POINT TO A LARGER THAN EXPECTED LIGHTNING NOx SOURCE

Hudman et al. [2007a]

GEOS-Chem (Lightning X4)Observed

NOx (8-12 km)

[ppb

v]

DOESN’T APPEAR TO BE A NOx LIFETIME ISSUE

NO: W. Brune, NO2: R. Cohen/T Bertram

Lightning parameterization (flashes/km2/s):

Land : ~CTH4.9 , Ocean: ~CTH1.73

CTH= Cloud Top Height

Price and Rind [1992]

GEOS-Chem Vertical Distribution

GEOS-Chem

NLDN

[Fla

shes

km

2 s]

FLASH RATES WELL SIMULATED POINTING TO A LARGER YIELD/FLASH AT NORTHERN MIDLATITUDES

Flash Comparison

Pickering et al., [1998]

Hudman et al. [2007a]

[Huntrieser et al., 2005]

PEAK CURRENT AS A FUNCTION OF LATITUDE

[Ken Pickering]

NO PRODUCTION RATE CALCULATED FROMR RECENT CAMPAIGNS

Standard GEOS-Chem mean flash rate was 125 mol flash-1 (Improved X4 500 mol flash-1)

OZONE COMPARISON INTEX-NA SOUTHEAST U.S. Increase in lightning yield X4 to 500 mol/flash has ~10 ppbv effect on

ozone

NO2O3

Hudman et al. [2007a]…suggests great sensitivity of ozone to climate change

Observed Simulated Improved Simulation

2004 was not an anomalous lightning year

Hudman et al. [2007b]

SUMMERTIME NORTH AMERICAN OZONE ENHANCEMENTS

Biomass Lightning Anthropogenic

Simulated Observed All

North American

Source

NOx

Emission (Tg N)

Ozone Production Efficiency

Hemispheric ozone

enhancement (Tg, %)

Lightning 0.28 32.5 9.1 (5.1%)

Biomass burning

0.32 17.55.6 (3.1%)

Fossil fuel 0.72 15 10.9 (6.1 %)

All 1.32 19 25.6 (14.3 %)

NA Enhancement to Hemispheric Ozone

ICARTT DC-8~ Equal contributions for lightning and anthropogenic emissions in free troposphere and to NH burden

Hudman et al. [2007b]

NORTH AMERICAN ENHANCEMENT TO HEMISPHERIC OZONE

1. PAN decomposition represents a major and possibly dominant component of the ozone enhancement in transpacific Asian pollution plumes.

2. A factor of 10 dilution of Asian pollution plumes takes place during entrainment in the U.S. boundary layer, greatly reducing their impact at U.S. surface sites.

3. California mountain sites are more sensitive to Asian pollution because of their exposure to the free troposphere. Asian enhancements are 7-10 ppbv during NAAQS exceedances; unlike at surface sites, Asian pollution influence is not minimum under high-ozone conditions.

4. A 50% summertime powerplant/industry NOx reduction source 1999 results in an 4 – 8 ppbv reduction in ozone at the surface with maximum effect in the southeast.

5. Anthropogenic CO emission in NEI 99 is overestimated by 60%.

6. The biogenic CO source now exceeds the anthropogenic source in summer.

MAJOR FINDINGS (1)

7. dO3/dCO in NA boundary layer outflow is ~28% higher than in the early 1990s, consistent withour understanding of changes in OPE and emissions.

8. Lightning is the dominant source of UT NOx over United States during the summer and had ~10 ppbv impact on upper tropospheric ozone.

9. Successful simulation of lightning over the U.S. requires a factor of 4 increase in NOx yield to 500 mol flash-1.

10. Lightning & Anthropogenic emissions each enhance ozone by 10-15 ppbv in the upper free troposphere over the U.S. Biomass burning enhancement over the Eastern U.S. was greatest below 4 km (~3-4 ppbv).

11. Lightning & anthropogenic emissions have a roughly equal enhancement to hemispheric ozone (~5%) during the summer.

12. Biomass burning emissions enhance surface ozone over Western Europe by 3-5 ppbv, comparable to the enhancement from fossil fuel.

MAJOR FINDINGS (2)

Acknowledgements

-I would like to whole-heartedly thank my advisor, Daniel Jacob, who is a brilliant scientist, patient mentor, and a good person.

-The research group (past and present)

+ Justin, Jenny, Peter, Moeko

Disclaimer: I am not leaving

"If you light a lantern for another, it will also brighten your own way" -- Nichiren Daishonin (Gosho Zenshu, p. 1598).

More Acknowledgements

Disclaimer: I am not leaving

-“THANKS” Lee Murray

- Bob Yantosca, Jack Yatteau, and Phillipe Le Sager

-Brenda Mathieu, Cecilia McCormack

-Dylan Millet, Colette Heald, Soléne Turquety, Lin Zhang, Folkert

Boersma, Qinbin Li, Lyatt Jaeglé, Qing Liang, Mat Evans

- ITCT 2k2/PEACE, ICARTT, INTEX-B Science Teams…in particular

Yutaka Kondo, Jim Crawford, Hanwant Singh, David Parrish, Owen

Cooper

- Jennifer Logan and Loretta Mickley (New bosses)

- NSF and AMS/NOAA graduate fellowships

**This work was funded by NOAA Office of Global Programs, NASA

Global Tropospheric Chemistry Program

Even more Acknowledgements

-My mom and Henry a constant source of support and love. The rest of my family!

-Rob Kay (Thanks for coming Penny and Mark!)

-Some dear friends: Debbie Sorenson, Nenita Elphick, Julie Schlenker, May Fu, Monika Kopacz, Colette Heald, Noelle Eckley, Mary Farrow, Yaping Xiao

-My great friends in the SGI-USA & World Peace Buddhist Society campus club

Disclaimer: I am not leaving

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