# Presentation: 224404

## North America as a Source and Receptor 

- 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 **
**of Hemispheric Ozone Pollution: **
**Seasonal Variability, Uncertainties, **
**and Policy Implications **

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

**Arlene M. Fiore**
**A33-E01**

## Wide range in prior estimates of intercontinentalsurface 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**

**Surface O****3**** contribution **
**from foreign region (ppbv)**

- A.M. Fiore

**Notes:**
2 example S-R pairs

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

**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. NO****x****, 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

**Simulated vs. observed monthly mean surface O****3**

**CENTRAL EUROPE**

**Surface Ozone (ppb)**

**High bias over EUS **
**in summer and early fall**

**EASTERN USA**

**OBS (CASTNet)**

**MODELS**

**MODEL ENS. MEAN**

**Month of 2001**

**Seasonal cycle**
**captured 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

**(1.64)**

**Full range of **
**15 individual **
**models**

**Annual mean surface O****3**** decrease from **
**-20% NOx+CO+NMVOC regional anthrop. emissions**

**“****Sum 3 foreign”**

**“****domestic”**

**ppbv**

**“****import sensitivity”**

- A.M. Fiore

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

**SA**

**EU**

**EA**

**SUM OF 3 FOREIGN REGIONS**

**15- MODEL MEAN SURFACE**
**O****3**** DECREASE (PPBV)**

**Spring (fall) max due to longer O****3**** 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 

**CO**

**NO****x**

**NMVOC**

**NO****x****+NMVOC+CO**

** ****MODEL ENSEMBLE MEAN SURFACE**
**O****3**** DECREASE (PPBV)**

**Wide range in EU anthrop. NMVOC inventories **
****** ****large uncertainty in the estimated response of NA O****3**

- A.M. Fiore

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

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

**Surface O****3**** response to -20% domestic**
**(NA NOx+NMVOC+CO) anthrop. emis.**

**PPBV**
**RATIO**

- Response to -20%
- Foreign > Domestic
- (winter)

- A.M. Fiore

**Notes:**
Conclude that response to foreign, although 10ths of ppb is not trivial when compared with response to equivalent % reductions in domestic anthrop. Emissions... Point out “shoulder” = “high-transport” seasons, where future growth in foreign emissions may extend season of poor air quality

## North America as a source of ozone pollution

**Source region:**

**sum of 3 foreign regions**

**Receptor region:     **NA**  ****        ****EU****           ****E Asia****       ****S Asia****  **

**Full range of **
**15 individual **
**models**

**Annual mean surface O****3**** decrease from **
**-20% NOx+CO+NMVOC regional anthrop. emissions**

**Import sensitivity:    **  0.45             **0.75                 0.65                 0.45**

- A.M. Fiore

**Notes:**
NA = same from previous slide; now same analysis for the 3 foreign regions... define import sensitivities, then focusing on NA influence elsewhere... 
Finish: Black bars = sum of 3 foreign regions – finish by comparing this response to “conventional” precursors to the response to CH4... 

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

**Full range of **
**18 models**

**ppb**

**EU              NA            E Asia        S Asia  **

**1 ppbv O****3**** decrease **
**over all regions **
- [Dentener et al.,2005;
- Fiore et al., 2002, 2008;
- West et al., 2007]

**Estimate O****3**** response to -20% regional CH****4 ****anthrop. emissions to**
**        ****compare with O****3**** response to**** NOx+NMVOC+CO:**
** ****-20% global [CH****4****]  ****≈**** -25% global anthrop. CH****4**** emissions **
** ****Anthrop. CH****4**** emis. inventory **[*Olivier et al*., 2005]** for regional emissions **
** ****Scale O****3**** response (linear with anthrop. CH****4**** emissions **[Fiore et al., 2008]**)**

- A.M. Fiore

**Notes:**
20% global CH4  -25% global anthrop. Emissions (accounting for feedback of methane on its own lifetime (F = 1.33)+ anthrop = 60% total CH4 emissions [IPCC 2007])

## 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)

**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 uncertainties**
- Robust: NAEU largest; SAothers 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 CH****4**** yields an O****3**** decrease similar to that achieved with NO****x****+NMVOC+CO over foreign regions (0.4-0.6 ppb for 20% reductions)**

**www.htap.org for 2007 TF HTAP Interim Report**
**and information about TF HTAP activities**

- A.M. Fiore

**Notes:**
Mention need to understand large O3 bias + EU anthropogenic NMVOC emissions
 Importance of shoulder seasons + potential for degradation of air quality with future global rise
 Point out CH4 – also benefits climate; low-cost options available in industrialized nations where conventional controls getting more costly