F.J. Dentener, C. Cuvelier, M.G. Schultz, O. Wild, T.J. Keating, A. Zuber, S. Wu, C. Textor, M. Schulz, C. Atherton, D.Bergmann, I. Bey, G. Carmichael, R. Doherty, B. Duncan, G. Faluvegi, G. Folberth, M.G. Vivanco, M. Gauss, S. Gong, D. Hauglustaine, P. Hess, T. Holloway, L. Horowitz, I. Isaksen, D. Jacob, J. Jonson, J. Kaminski, A. Lupu, I. MacKenzie, E. Marmer, V. Montanaro, R. Park, K. Pringle, J. Pyle, M. Sanderson, S. Schroeder, D. Shindell, D. Stevenson, S. Szopa, R. Van Dingenen, P. Wind, G. Wojcik, G. Zeng

North America as a Source and Receptor North America as a Source and Receptor of Hemispheric Ozone Pollution: of Hemispheric Ozone Pollution:

Seasonal Variability, Uncertainties, Seasonal Variability, Uncertainties, and Policy Implications and Policy Implications

Joint Assembly, Fort Lauderdale, FL, May 28, 2008

Arlene M. FioreA33-E01

Wide range in prior estimates of intercontinentalsurface ozone source-receptor (S-R) relationships

Assessment hindered by different (1) methods, (2) reported metrics, (3) meteorological years, (4) regional definitions

Few studies examined all seasons

ASIA NORTH AMERICA NORTH AMERICA EUROPE

annual mean

events

seasonal mean

Studies in TF HTAP [2007] + Holloway et al., 2008; Duncan et al., 2008; Lin et al., 2008

events

seasonal mean

annual mean

Surf

ace

O3 c

ontr

ibut

ion

from

fore

ign

regi

on (p

pbv)

A.M. Fiore

Objective: Quantify & assess uncertainties in N. mid-latitude S-R relationships for ozone

BASE SIMULATION (21 models): horizontal resolution of 5°x5° or finer 2001 meteorology each group’s best estimate for 2001 emissions methane set to 1760 ppb

SENSITIVITY SIMULATIONS (13-18 models): -20% regional anthrop. NOx, CO, NMVOC emissions,

individually + all together (=16 simulations) -20% global methane (to 1408 ppb)

TF HTAP REGIONS

A.M. Fiore

Simulated vs. observed monthly mean surface O3

CENTRAL EUROPE

Surf

ace

Ozo

ne (p

pb)

High bias over EUS in summer and early fall

EASTERN USA

OBS (CASTNet)

MODELS MODEL ENS. MEAN

Month of 2001 Seasonal cyclecaptured over Europe

Greater uncertainty in results for summertime NA

OBS (EMEP)

A.M. Fiore

North America as a receptor of ozone pollution: Annual mean foreign vs. domestic influences

0

0.2

0.4

0.6

0.8

1

NA

0

0.2

0.4

0.6

0.8

1

NA

NA EU EA SA EU+EA+SASource region:(1.64)

Full range of 15 individual models

Annual mean surface O3 decrease from -20% NOx+CO+NMVOC regional anthrop. emissions

domestic= 0.45

∑ 3 foreign

“Sum 3 foreign”“domestic”

ppbv

“import sensitivity”

Seasonality?

A.M. Fiore

North America as a receptor of ozone pollution: Seasonality of response to -20% foreign anthrop. emissions

SAEUEA

SUM OF 3 FOREIGN REGIONSSpring max

Similar response to

EU & EAemissions

Apr-Nov(varies by

model)

15- M

OD

EL M

EAN

SU

RFA

CE

O3 D

ECR

EASE

(PPB

V)

Spring (fall) max due to longer O3 lifetime, efficient transport [e.g., Wang et al., 1998; Wild and Akimoto, 2001; Stohl et al., 2002; TF HTAP 2007] A.M. Fiore

North America as a receptor of ozone pollution:Seasonality of response to -20% foreign anthrop. emissions

CONOx

NMVOC

NOx+NMVOC+CO

MO

DEL

EN

SEM

BLE

MEA

N S

UR

FAC

EO

3 DEC

REA

SE (P

PBV)

Wide range in EU anthrop. NMVOC inventories large uncertainty in the estimated response of NA O3

Comparable response to NOx & NMVOC emissions(but varies by model)

A.M. Fiore

North America as a receptor of ozone pollution: Seasonality in “import sensitivity”

IMPORT SENSITIVITY:

-20% domestic

∑ (-20% 3 foreign)

Surface O3 response to -20% domestic(NA NOx+NMVOC+CO) anthrop. emis.

PPB

VR

ATI

O

0.4-0.8 during spring “high transport season”

~0.2 when domestic O3 production peaks in summer

Response to -20% Foreign > Domestic

(winter)

A.M. Fiore

North America as a source of ozone pollution

Source region:

00.20.40.60.8

11.21.4

NA EU EA SA

ppb

00.20.40.60.8

11.21.4

NA EU EA SA

NA EU EA SA sum3sum of 3 foreign regions

Receptor region: NA EU E Asia S Asia

Full range of 15 individual models

Similar impactfrom 3 foreignregions

Annual mean surface O3 decrease from -20% NOx+CO+NMVOC regional anthrop. emissions

Largest foreign S-R pair

Import sensitivity: 0.45 0.75 0.65 0.45

A.M. Fiore

Surface ozone response to -20% global [CH4]:similar decrease over all regions

Full range of 18 models

0

0.5

1

1.5

2

EU NA EA SA

ppb

EU NA E Asia S Asia

1 ppbv O3 decrease over all regions [Dentener et al.,2005; Fiore et al., 2002, 2008; West et al., 2007]

Estimate O3 response to -20% regional CH4 anthrop. emissions to compare with O3 response to NOx+NMVOC+CO:

(1) -20% global [CH4] ≈ -25% global anthrop. CH4 emissions (2) Anthrop. CH4 emis. inventory [Olivier et al., 2005] for regional emissions (3) Scale O3 response (linear with anthrop. CH4 emissions [Fiore et al., 2008])

A.M. Fiore

Comparable annual mean surface O3 response to -20% foreign anthropogenic emissions of CH4 vs. NOx+NMVOC+CO

ppb

(Uses CH4 simulation + anthrop. CH4 emission inventory [Olivier et al., 2005]to estimate O3 response to -20% regional anthrop. CH4 emissions)

0

0.2

0.4

0.6

0.8

NA EU EA SA

NOx+NMVOC+CO CH4

Sum of annual mean ozone decreases from 20% reductions of anthropogenic emissions in the 3 foreign regions

Receptor: NA EU E Asia S Asia

A.M. Fiore

Conclusions: S-R relationships for O3 pollution

• Benchmark for future: Robust estimates + key uncertaintiesRobust: NAEU largest; SAothers smallest Uncertainties: Model transport, emissions, chemistry particularly NA in summer, EU/EA -> NA, NOx/NMVOC -> NA

• NA response to foreign anthrop. emissions 40-80% that to domestic anthrop. emissions in spring and late fall

• Reducing equivalent % of CH4 yields an O3 decrease similar to that achieved with NOx+NMVOC+CO over foreign regions (0.4-0.6 ppb for 20% reductions)

www.htap.org for 2007 TF HTAP Interim Reportand information about TF HTAP activities

A.M. Fiore