J. E. Williams, ACCRI, The Impact of ACARE reductions in Future Aircraft NOx Emissions on the Composition and Oxidizing Capacity of the Troposphere in 2050 J. E. Williams, . Hodnebrog, P. F. J. van Velthoven and the QUANTIFY modeling team

J. E. Williams, ACCRI, EU-QUANTIFY (FP6) Quantifying the Climate Impact of Global and European Transport Systems Emission datasets used in this study available on the site Activity 3: Large-scale Chemistry Effects Related Publications: P. Hoor, et al., The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY, Atms. Chem. Phys., 9, , (Preliminary Emission Estimates) G. Myhre et al., Radiative forcing due to changes in ozone and methane caused by the transport sector, Atms. Environ., 45, , O. Hodnebrog et al., Future Impact of non-land based traffic emissions on atmospheric ozone and OH – an optimistic scenario and a possible mitigation strategy, in preparation.

J. E. Williams, ACCRI, Quantify Transport Emission Estimates for NO x B1 Scenario (optimistic) : Abatement and mitigation procedures are effective Fraction of NOx from air decreases for ACARE Scenario Warming potential per NOx from AIR highest due to release in the UTLS (Fuglestvedt et al., 2008) ACARE : Advisory Council for Aeronautical Research in Europe

J. E. Williams, ACCRI, B1 and B1 ACARE Aircraft Emission Estimates TgN yr TgN yr TgN yr TgN yr -1

J. E. Williams, ACCRI, Variability in the Latitudinal Distribution of B1 Aircraft NOx emissions Gg N yr -1 Growth in air NOx in Tropics between 2000 – 2050; Peak in NH at 2025 Relative partitioning towards Tropics increases in the Future

J. E. Williams, ACCRI, QUANTIFY Model Ensemble Model (Institute)Hor. ResLevelsChemical Species (Trans./Total.) Reactions TM4 (KNMI, NL)3° x 2°34 (0.1)26/42 (Trop)68 p-TOMCAT (UCAM- DCHEM, UK) 2° x 2°31 (10)35/51 (Trop)112 OsloCTM2 (UiO, Norway) T4260 (0.1)76/98 (Trop/Strat)163 LMDz-INCA (LSCE, Fr)3.75° x 2.5°19 (3)66/96 (Trop)291 UCI CTM (UCI, US)T4237 (2)28/38 (Trop/LINOZ)90 MOCAGE (Meteo-France, Fr) 2° x 2°47 (5)89/30 (Trop/Strat) ECMWF OD meteorology for 2003 used throughout. 5 CTMs and 1CCM. Background CH4 increased according to projections. Experimental Methodology: 5% perturbation in Emissions from each transport sector Scaled to ~100% (Grewe et al, GMD, 2010)

J. E. Williams, ACCRI, NH Perturbations in O 3 : Ensemble model mean B1ACARE scenario only emission scenario with lower O3 than 2000 in ensemble mean Non-linearites cause 2025 to be < 2050

J. E. Williams, ACCRI, Global tropospheric O 3 budget (TM4) Tg O 3 yr B12050 B1 ACARE Total NO x Emissions (Tg N yr-1) Chemical Production (+4.1%) (+3.4%) Chemical Destruction (+3.5%) (+2.9%) Dry Deposition (+16.5%)696.2 (+4.1%) Strat-Trop exchange (+1.4%)526.4 (-0.3%) Trop. Burden/Lifetime302 (22.2)329 (23.4)328 (23.4) Although Total NOx emissions  ~8% in B1 net chemical O 3 prod.  0.6% (0.5% w/ ACARE) Increases in Air traffic in Tropics compensate for Global NOx reduction

J. E. Williams, ACCRI, NH Perturbations in UTLS OH : Ensemble Mean Average between hPa

J. E. Williams, ACCRI, Influence on Surface Air Quality: 2003 vs 2050 B1 BO3 :  25 Tg (+5.4%) ; BCO :  42 Tg (-7.5%) ; BCH4 :  1425Tg (+37.6%) NO + CH3O2  NO2  O3 Background [O3] increases by ~5-10% in Pristine areas Decreases over populated regions from Industrial and Traffic Mitigation

J. E. Williams, ACCRI, Impact of Air traffic emissions on air quality: 2050 B1 Aircraft Emissions fully removed : Impact on surface O3 Increases surface O3 in NH by ~1-5%

J. E. Williams, ACCRI, Impact of ACARE emissions on air quality: 2050 B1 ACARE emissions  surface [O3] by ~0.5-2% in NH as a result of ACARE NOx reductions Mitigates increases in background [O3] due to CH4  (enhanced NOx recycling)

J. E. Williams, ACCRI, Impact of ACARE emissions on Oxidising Capacity: B B1 ACARE τ( CH 4 ) yrs τ( CO ) months OH + CH 4 (+ O 2 ) > CH 3 O 2 + H 2 O ~16% OH + CO > HO 2 + H 2 O + CO 2 ~ 40% There is a feedback in that reducing aircraft NOx increases the atmospheric lifetime of methane thus increasing the RF component Effect could be mitigated with increasing Relative Humidity due to rising Temperatures

J. E. Williams, ACCRI, Radiative Forcing from ΔO 3, ΔCH 4 and CH 4 -induced ΔO 3 RF (mW m -2 ) ΔO3ΔO3 Δ CH 4 CH 4 -induced Δ O 3 Total 2050 B (9.0)-17.8 (4.0)-6.5 (1.5)1.9 (6.4) 2050 B1 ACARE 18.9 (6.8)-14.3 (3.4)-5.2 (1.2)-0.6 (4.6)

J. E. Williams, ACCRI, Conclusions Future aircraft emissions peak in 2025 for NH and 2050 for the Tropics in B1 Scenario. There is a seasonal dependency in the magnitude of effects, where strong photolytic activity amplifies differences. Aircraft emissions contribute ~1-5% towards surface O 3 in 2050 for the B1 Emission Scenario. Introducing ACARE Technology has the potential to reduce surface O 3 ~1-2%. Introducing ACARE Technology changes the RF potential from slightly +ve to slightly –ve, although the std. dev. in the model ensemble is large.