# Presentation: 926204

## Intercontinental Source-Receptor Relationships for Ozone Pollution

** **
**Intercontinental Source-Receptor Relationships for Ozone Pollution**

- 40th Air Pollution Workshop and Symposium, Raleigh, NC, April 7, 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**

**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?

## How do we estimate source-receptor (S-R) relationships that describe hemispheric transport of air pollution?

**Measurements at remote sites?**
**(Monitoring site at Yosemite NP)**

**Models with anthropogenic **
**emissions reduced in source regions?**

**3D Model Structure**

**Difficult to directly measure a region’s contribution to pollution**
** ****over a receptor region, particularly for ozone [*****e.g.***** *****Goldstein et al*****., 2004]**

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

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

**2030 A1**

**1995 Base case**

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

**By 2030 under the Current LEgislation (CLE) scenario, **
**“****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?  **

- GEOS-Chem Model (4°x5°)
- [*Fiore et al., GRL*, 2002]

**U.S. air quality degrades despite domestic emissions controls (A1 2030)**

**U.S. grid-square days with 1-5p.m. O****3**** > 70 ppb**

## 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**

## Multi-model assessment involving >25 modeling groups  

**HTAP S-R Regions**

_**OBJECTIVES**_**: **Quantify S-R relationships for HTAP regions 		              **and assess uncertainties in these estimates**

**Focus species:**
** ****Ozone and precursors**
** ****Aerosols and precursors**
** ****Mercury**
** ****Persistent Organic Pollutants**
** ****Idealized Tracers**
** ****Oxidized Nitrogen**

_**PRODUCTS**_**: 2007 Interim Report**** **to inform the review of the 			1999 CLRTAP Gothenburg Protocol to abate acidification, 		eutrophication, and tropospheric ozone (**www.htap.org**).** **
**	****	**
**	****	****2009 Assessment Report****  **to inform the CLRTAP 			on hemispheric air pollution and S-R relationships.

## Wide range in literature estimates of mean surface O3 S-R relationships at northern mid-latitudes

**Wide range in literature estimates of mean surface O****3**** S-R relationships at northern mid-latitudes**

**Receptor = Asia**

**Receptor = Europe**

**Receptor = North America**

**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

## Model Setup for TF HTAP Ozone S-R Study 

**BASE SIMULATION**
**	******** ****horizontal resolution of 4****°****x5****°**** or finer**
**	******** ****2001 meteorology**
**	******** ****each group’s best estimate for emissions in 2001**
**	******** ****methane set to a uniform value of 1760 ppb**
**SENSITIVITY SIMULATIONS (17 total) with sustained 20% decreases in**
**	******** ****regional anthrop. NO****x****, CO, NMVOC emis. individually (4x3)**
**	******** ****regional anthrop. emis. of all O****3**** and aerosol precursors (4)**
**	******** ****global methane (to 1408 ppb)**

**HTAP REGIONS**

- A.M. Fiore

## Large inter-model range; 21-model mean generally captures observed monthly mean surface O3 

**Large inter-model range; 21-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

## Estimates of S-R relationships: Annual mean surface O3 decrease from 20% reductions in anthropogenic NOx+CO+NMVOC emissions

**Source region:**

****** ****But... seasonality in sensitivity to domestic vs. foreign sources?**

**sum of 3 foreign regions**

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

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

- A.M. Fiore

## Model ensemble mean surface O3 response over NA to decreases in anthropogenic emissions of O3 precursors

****** ****Import Sensitivity for NA in July ~ 0.2, in April ~ 0.6**

- A.M. Fiore

## Model ensemble mean surface O3 response over NA to decreases in anthropogenic emissions of O3 precursors

**Foreign impact on NA**
- (sum of O3 responses to -20% anthrop. emis. in the 3 foreign regions)

- A.M. Fiore

## Summary: Intercontinental S-R  relationships for O3 and conventional O3 precursors

**Identified robust estimates + key areas of uncertainty**
- Model ensemble mean overestimate vs. obs in summer EUS and Japan
- Robust: NAEU largest; SAothers smallest
- Uncertainty in relative roles of EU/EA  NA
- Uncertainty in exported EU O3 from EU AVOC emissions inventories

**Import sensitivities in other regions?**
**Comparison with prior literature?**

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

**Robust conclusions:**
**NA>EA>SA on EU ozone**
**NA and EU often > SA or EA on each other; **
-    dominant contributor varies across models
****** ****Ozone over foreign regions generally least sensitive to SA emissions**

**Import sensitivities during month of max. domestic or foreign sensitivity:**
**   ****EU: 0.7 (APR) 0.3 (JUL)    EA: 1.1 (MAR) 0.2 (JUL)    SA: 0.5 (NOV)**

- A.M. Fiore

## Range of estimated S-R relationships narrows from that in the literature with consistently applied HTAP approach 

**Receptor = EA**

**Receptor = EU**

**Receptor = NA**

- Assume linearity, scale response to -20% to 100% to estimate total contribution

- A.M. Fiore

**Notes:**
Methods – tagging vs. sensitivity simulations.

##         Summary: Intercontinental S-R  relationships for O3 and conventional O3 precursors

**Identified robust estimates + key areas of uncertainty**
- Uncertainty in exported EU O3 from EU AVOC emissions inventories
- Robust: NAEU largest; SAothers smallest
- Uncertainty in relative roles of EU/EA  NA; EU/NAEA/SA
- Model ensemble mean overestimate vs. obs in summer EUS and Japan
**Estimated “import sensitivities”**
- 0.2-0.3 July EA/NA/EU (max domestic production)
- 0.6-0.9 April EA/NA/EU (max foreign influence)
- 0.5 November SA (max foreign+domestic influence)
**Narrowed range of estimates from that in the literature**

**How does role of CH****4**** compare with NO****x****+CO+NMVOC?**

## Globally reducing methane decreases surface ozone everywhere

**Globally reducing methane decreases surface ozone everywhere**

**Change in population-weighted **
**mean 8-hr daily max surface O****3**** **
**in 3-month “O****3**** season” (ppbv)**

**Steady-state results from MOZART CTM**

*West et al., GRL, 2007*

**1995**
**(base)**

**50% **
**anth.**
**VOC**

**50% **
**anth.**
**CH****4**

**50% **
**anth.**
**NO****x**

**2030 **
**A1**

**2030 **
**B1**

**Number of U.S. summer grid-square days with O****3**** > 80 ppbv**

- GEOS-Chem results
- Fiore et al., GRL, 2002

****** ****Examine role of CH****4**** vs. NO****x****+CO+NMVOC in multi-model context**

**Notes:**
Per ppb o3 change CH4 best for climate ; Time Scale

## Surface ozone decreases similarly in all HTAP regions when global methane is reduced

** ****~1 ppbv O****3**** decrease over all NH receptor regions**
** ****Consistent with prior studies**

**Can we scale these results to 20% reductions in regional anthrop.**
**CH****4**** emissions to compare with conventional O****3**** precursors?  **

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

**ppb**

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

- A.M. Fiore

**Notes:**
20% global CH4  -25% global anthrop. Emissions (using 1.33 feedback factor)

## 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 O3 decrease from 20% reductions in foreign CH4 emissions and NOx+NMVOC+CO

- Use CH4 simulation + EDGAR 3.2 FT2000 CH4 emissions [*Olivier et al*., 2005]
- to estimate O3 response to -20% regional anthrop. CH4 emissions

- A.M. Fiore

##  Conclusions: Intercontinental S-R Relationships for O3

- Identified robust estimates + key areas of uncertainty
- Model ensemble mean overestimate vs. obs in summer EUS and Japan
- Robust: NAEU largest; SAothers smallest
- Uncertainty in relative roles of EU/EA  NA
- Uncertainty in exported EU O3 from EU AVOC emissions inventories
- Estimated “import sensitivities”
- 0.2-0.3 July EA/NA/EU (max domestic production)
- 0.6-0.9 April EA/NA/EU (max foreign influence)
- 0.5 November SA (max foreign+domestic influence)
- Narrowed range of estimates from that in the literature under HTAP setup
- Combined reductions in regional anthropogenic CH4 + conventional O3 precursors roughly double the O3 decrease over foreign regions

**How might climate change affect hemispheric transport of air pollution?**
**Are our S-R relationships consistent with rising Asian emissions driving **
**a 0.1-0.5 ppb yr****-1**** surface O****3**** increase (as derived from observations)? **

## Global background ozone may decrease in a warmer, more humid climate

**Mean annual change in number of days where daily max 8-hr O****3**** > 80 ppbv**
**(2090-2100 A1) – (1990-2000)****  **

- MOZART-2 global tropospheric chemistry model with meteorology from NCAR climate model [Murazaki and Hess, *J. Geophys. Res*., 2006]

- More inflow of clean air from Gulf of Mexico

**Less trans-Pacific transport**

**Increase in polluted **
**(high-NO****x****) regions**

- A.M. Fiore

## Apply S-R relationships to address hypothesis of rising background O3 driven by increasing Asian emissions

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

- A.M. Fiore