GEOS-Chem Users Meeting April 12, 2007

U.S. INFLUENCE ON TROPOSPHERIC OZONE AND THE EFFECTS OF RECENT EMISSION REDUCTIONS

Modeling: Rynda Hudman*, Lee Murray, Daniel Jacob, Solene Turquety, Dylan Millet, Shiliang Wu

NEI 99 Emissions: Alice Gilliland

ICARTT Observations: Melody Avery, Tim Bertram, Ron Cohen, Jack Dibb, Frank Flocke, Allen Goldstein, John Holloway, Andy Neuman, Tom Ryerson, Glen Sachse, Hanwant Singh, P J Wooldridge

ICA

RT

T F

light

Tra

cks

North America Europe

NOx stationary sources 50%

Anthropogenic CO 60%

4

2

6

8

Alt (km)

10

O3 (ppbv)

BB NA FF Lightning

NOx/flash4X larger than previously assumed!

Export well constrained

effects on O3 & OPE Northern Hemisphere Burden

ICARTT CONSTRAINTS ON SUMMERTIME EMISSIONS & HEMISPHERIC OZONE

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(v7.02.04 w/ modifications below)

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 Median NO2

Median Model / Observed NOx (0-2 km)

[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)

NO2 (ppbv)

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

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 due to this bias)

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

From these estimates 2004 emissions 45% lower than NEI 99 (Our estimate 60%)

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 consistent with decadal changes in emissions and OPE over the Northeaster United States

Overestimate of tropical background

WINDS FROM W-SE

ALL WIND DIRECTIONS

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

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

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)

Fuel - based inventory + CO & CO/NOx ambient trends inferred emissions

[Parrish et al., 2006]

EVALUATION OF EPA NEI99 ON-ROAD TRANSPORT EMISSIONS

On-road emission estimates

*Note: 2004 trends report is same as NEI99

On-Road transport inventories (1995)

On-road CO emissions too high by 50%

UNITED STATES NOx REGULATIONS AIMED AT REDUCING OZONE SMOG

• 1998 - The EPA NOx SIP Call mandated that 22 eastern states & DC revise their SIPs to meet NOx emissions reductions by 2003 (Phase 1) and further reduction by 2007 (Phase 2).

• 2003 - All 22 states reduced NOx point source emissions to their Phase 1 levels.

• 2004 - Frost et al., [2006] determined that as a result emission rates of power plant NOx have decreased approximately 50% between 1999 and 2003.

• 2005 - NOx levels in the U.S. will likely continue to drop. In March 2005, the EPA issued the Clean Air Interstate Rule, which will, permanently reduce NOx emissions to 60% of 2003 levels in 25 eastern states, and the DC.

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

50% NOx PP reduction

Frost et al., [2006]NOx SIP

SIP Phase 1

SIP Phase 2

CAIR

Frost et al., [2006]

0.75 1.50 2.25

CH2O (ppbv)

298

168

157

164

166

156

119

138

173

114

0

54

0.0 0.5 1.0 1.5

Propane (ppbv)

2

4

6

8

10

12

Alti

tude

(km

)

257

142

154

184

210

209

155

172

204

133

0

77

ObservationsGEOS-Chem

CO OVERESTIMATE IS NOT CAUSED BY INSUFFICIENT VENTILATION OR BIOGENIC SOURCE

Boundary layer ventilation is constrained by vertical profile of short-lived VOCs

Biogenic VOCs are well-constrained by successful simulation of formaldehyde

Propane: E. Atlas CH2O: Alan Fried

[Provided by D. Millet]

CHEBOGUE POINT CO TIMESERIESBias still exists during outflow events

7/1 8/1

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]

[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]

NORTH AMERICAN ENHANCEMENT TO HEMISPHERIC OZONE