# Presentation: 854133

## Hemispheric Transport of Ozone Pollution:  

** **
**Hemispheric Transport of Ozone Pollution:  **
**Multi-model Assessment of the Role of Methane **
**and the Conventional Ozone Precursors **

- Quadrennial Ozone Symposium, Tromsø, Norway, July 2, 2008

**Arlene M. Fiore**
**(arlene.fiore@noaa.gov)**

- F. Dentener, O. Wild, C. Cuvelier, M. Schultz, C. Textor, M. Schulz, C. Atherton, D. Bergmann, I. Bey, G. Carmichael, R. Doherty, B. Duncan, G. Faluvegi, G. Folberth, M. Garcia Vivanco, M. Gauss, S. Gong, D. Hauglustaine, P. Hess, T. Holloway, L. Horowitz, I. Isaksen, D. Jacob, J. Jonson, J. Kaminski, T. Keating, 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, J. West, S. Wu, G. Zeng, A. Zuber

## Evidence of intercontinental transport at northern midlatitudes: 2001 Asian dust event

**Glen Canyon, Arizona, USA**

**Evidence of intercontinental transport at northern midlatitudes: 2001 Asian dust event**

**Dust leaving the Asian coast in April 2001**

**Image c/o NASA SeaWiFS Project and ORBIMAGE**

**Notes:**
Focus only on dust – satellite image of dust coming across pacific?

## Regional control efforts (even under optimistic scenarios)may be offset by increases in hemispheric ozone pollution

| IPCC 2030
Scenario | Anthrop. NOx emis.
Global            U.S. |  | Methane emis. |
| --- | --- | --- | --- |
| A1 | +80% | -20% | +30% |

**By 2030 **under the CLE scenario (considers air pollution regulations),** **
**“****the benefit of European emission control measures is...**
**significantly counterbalanced by increasing global O****3 ****levels...”**
- [*Szopa et al*., *GRL*, 2006]

****** ****International approach to ozone abatement?  **

## Convention on Long-Range Transboundary Air Pollution (CLRTAP)

**Co-chairs: Terry Keating (U.S. EPA) and Andr****é**** Zuber (EC)**

**TF HTAP Mission: Develop a fuller understanding of hemispheric transport **
**               ****of air pollution to inform future negotiations under CLRTAP**

**51 parties in Europe, North America, and Central Asia**

**www.htap.org for more information + 2007 TF HTAP Interim Report**

## Wide range in prior estimates of intercontinentalsurface ozone source-receptor (S-R) relationships

**Wide range in prior estimates of intercontinental****surface ozone source-receptor (S-R) relationships**

**Receptor = Asia**

**Receptor = Europe**

**Assessment hindered by different:**
**methods **
**regional definitions**
**reported metrics**
**years (meteorology) **
**Adopt a multi-model approach**
**Consistency across models**
**Examine all seasons**

- Estimates are from studies cited in TF HTAP [2007] Ch5, plus new work [*Holloway et al*., 2008; *Duncan et al*., 2008; *Lin et al*., 2008]

- A.M. Fiore

**Notes:**
Little boxes – just one or two studies

## 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

## Large inter-model range; multi-model mean generally captures observed monthly mean surface O3 

**Large inter-model range; multi-model mean generally captures observed monthly mean surface O****3**** **

**Mediterranean**

**Central Europe < 1km**

**Central Europe > 1km**

**NE USA**

**SW USA**

**SE USA**

**Japan**

**Mountainous W USA**

**Great Lakes USA**

**Surface Ozone (ppb)**

- 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

**Notes:**
Springtime: 10 models equivalent; 4 EA 30-55% > EU; annual mean that is 8 predict equivalent & 6 suggest 25-50% greater from EA

## 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 O3

## 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.**

**PPB**
**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

## Estimates of S-R relationships for surface O3 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

## Surface O3 response to decreases in foreign anthropogenic emissions of O3 precursors

**Surface O****3**** response to decreases in foreign anthropogenic emissions of O****3**** precursors**

**Source region:   SUM3   ****NA ****  ****EA****   ****EU****   ****SA**

**EU receptor**

**EA receptor**

**SA receptor**

- Surface O3 decrease (ppb)

- A.M. Fiore

## Monthly mean import sensitivities

- A.M. Fiore

## Application of S-R relationships: Consistency between background O3 trends and reported changes in Asian emissions? 

**Assuming +10% yr****-1 ****Asian emissions, **
**our results imply an O****3**** increase **
**over NA and EU of at most 0.15 ppb yr****-1**
**OUR CAVEATS:**
**-- assumes SA+EA, + other emissions follow NO****x**
**-- continental-avg vs. “west coast” obs **

- A.M. Fiore

## Addressing Uncertainties: Quantifying model differences due to transport (vs. emissions and chemistry)  

**Example: SA ******** EA for CO **

**Emissions,**
**chemistry,**
**transport**
**vary**

**Only transport**
**varies**

**POSTER by Martin Schultz *****et al*****.:**
**Passive tracer simulations in the context of the**
**TF HTAP multi-model assessment activity**

**Model results averaged from surface to 1 km**

- A.M. Fiore

## 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])

## Tropospheric O3 responds approximately linearly to anthropogenic CH4 emission changes across models

**Tropospheric O****3**** responds approximately linearly to anthropogenic CH****4**** emission changes across models**

**Anthropogenic CH****4**** contributes ~50 Tg (~15%) to tropospheric O****3**** burden**
**	****	****	****            ****~5 ppbv to surface O****3**

*Fiore et al*., *JGR*, 2008

## 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: Hemispheric Transport of O3

**Benchmark for future: Robust estimates + key areas of uncertainty**
**“****Import Sensitivities” (******** O****3**** from anthrop. emis. in the 3 foreign vs. domestic regions): 0.5-1.1 during month of max response to foreign emis; 0.2-0.3 during month of max response to domestic emissions    **
**Our estimates + emis. trends ******** low end of observed surface O****3 ****trends**
**Comparable O****3**** decrease from reducing equivalent % of CH****4**** and NOx+NMVOC+CO over foreign regions (0.4-0.6 ppb for 20% reductions)**

- www.htap.org for more information + 2007 TF HTAP Interim Report

- ADDITIONAL QUESTIONS (TF HTAP work ongoing for 2010 report):
**How well do models capture the relevant processes (e.g. export,  **
**  ****chemical evolution, transport, mixing)?**
**Can we scale our estimated O****3**** responses to other combinations and**
**   ****magnitudes of emission changes?**
**What is the contribution of hemispheric transport to metrics relevant**
**   ****to attainment of O****3**** air quality standards?**

- A.M. Fiore