1. Hemispheric transport of ozone pollution and the nonlinearities GMI meeting UC Irvine March 17, 2008 Shiliang Wu, Harvard Bryan Duncan, NASA / GSFC Arlene Fiore, NOAA / GFDL Daniel Jacob, Harvard Oliver Wild, University of Lancaster

2. HTAP Multi-model approach to estimate intercontinental source-receptor (S-R) relationships for ozone 20% decreases in:  anthrop. emis. in HTAP regions for NO x, CO, NMVOC individually  anthrop. emis. of all O 3 and aerosol precursors in HTAP regions  global CH 4 Conduct base simulations with 3-D models  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 Conduct sensitivity simulations (17 total) NA EU SA EA (Slide from Arlene Fiore @ GFDL)

3. Estimates of S-R relationships: Springtime surface O 3 decrease in HTAP receptor regions from 20% reductions of O 3 precursors EU and NA ≥ SA RECEPTOR = EAST ASIA   20% foreign emis.) -20% domestic emis. ≈ 85% ppbv EA/EU contribute similarly EU VOC at least as important as NO x RECEPTOR = NORTH AMERICA ppbv   20% foreign emis.) -20% domestic emis. ≈ 55% SOURCE REGIONS:  3 foreign regions Larger uncertainty in role of foreign VOC (Slide from Arlene Fiore @ GFDL)

4. Some questions remaining  Why so large variations across models associated with the role of VOCs?  Can 20% emission perturbations be scaled to other magnitudes? (Do the perturbations show good linearity? – this could have implications for the relative importance of different precursors in impacting the regional ozone export)  Do different models have similar/consistent linearity/nonlinearity for various perturbations?

5. Large variations in EU AVOC inventories across models lead to large variations in calculated ozone export from EU GMI GEOS-Chem Annual mean NA surface O 3 decreases (ppb) in response to 20% EU anthro. NMVOC reductions in different models

6. Changes in surface O 3 due to changes in EU AVOC emissions (simulation results from GMI model for JJA) EU AVOC -20% Full perturb / (20% perturb x 5) EU AVOC = 0 Control (ppb) VOC perturbations are strongly linear

7. VOC perturbations show very good linearity for all seasons Changes in surface O3 over North America due to perturbations in EU anthro. VOC emissions (GMI results) How about NOx?

8. Changes in surface O 3 due to changes in EA NOx emissions (simulation results from GMI model for JJA) EA NOx -20% Full perturb / (20% perturb x 5)EA NOx = 0 Control (ppb) NOx perturbations show non-linearity

9. Sensitivity to NOx emissions for different intercontinental pairs - - - - (effects from -20% NOx) x 5 effects from -100%NOx The nonlinearities for NOx perturbations are even larger for other seasons. Distinctive seasonal pattern for the North America impacts on Europe? Source region: EA Source region: NA Source region: EU

10. Intercontinental influence on surface O 3 for different precursors Decrease in surface O 3 (ppb) due to foreign emission reductions 20% reductions (HTAP models / MAM) North America Europe East Asia South Asia Fiore et al. [2008] Sensitivity to VOC comparable to NOx 100% reductions (GMI/MAM) North America EuropeEast Asia 100% reductions (GMI/JJA) Much weaker sensitivity to VOC compared to NOx with full reductions or in summer

11. Intercontinental influence on surface O 3 for different regions Fiore et al. [2008] Foreign impact on NA (GMI) (HTAP) EU ~ EA? NA ~ EU Foreign impact on EA (GMI)

12. Consistency and discrepancy across models ( Changes in NA surface O3 due to changes in EU NOx emissions) - - - ( perturbations from -20% EU anthro. NOx) x 5 __ perturbations from zeroing out EU anthro. NOx MZ = MOZART-v2 (from Arlene) FR = FRSGCUNI (from Oliver)

13. - - - ( perturbations from -20% all EU anthro. emis) x 5 __ perturbations from zeroing out EU anthro. emis (NO x & VOC & aerosols) Consistency and discrepancy across models ( Changes in NA surface O3 due to changes in EU anthropogenic emissions)

14. On the family definition of O x O x = O 3 + O + NO 2 + 2 NO 3 + 3 N 2 O 5 + PANs + HNO 3 + HNO 4 O x = O 3 + O + NO 2 + 2 NO 3 + 3 N 2 O 5 + PANs + 2 HNO 3 + HNO 4 + other nitrates O x = O 3 + O + NO 2 + 2 NO 3 + 3 N 2 O 5 + PANs + 2 HNO 3 + 2 HNO 4 + HO 2 + OH … Inconsistency in the family definition of Ox in literature on ozone budgets, leading to ambiguities in model intercomparisons.

15. O3O3 O NO 2 NO 3 N2O5N2O5 HNO 3 RNO x HNO 4 OH HO 2 /RO2 HONO H 2 O 2 /ROOH Transport from stratosphere Deposition Carbonyls Emission h 1 2 O x family H 2 O, O 2 A new family definition of O x (Slide from Daniel Jacob) 0.5 1 1.5 2 3 O x = O 3 + O + NO 2 + 2 NO 3 + 3 N 2 O 5 + PANs + 1.5 HNO 3 + HNO 4 + 0.5 HO y

16. Thank you!