Effect of Aviation on Atmospheric Composition

Transcription

1 Effect of Aviation on Atmospheric Composition Cynthia Whaley, Kimberly Strong, Zen Mariani, and Steven Barrett (MIT) UTIAS Colloquium on Sustainable Aviation May 2013

2 Outline Introduction Composition of the atmosphere Climate change Effect of aviation on: Climate Change O 3 layer Air quality How we measure composition Effect of climate change on aviation Conclusions

3 Composition of the Atmosphere Jacobs, Lutgens and Tarbuck, The Atmosphere, 8th ed. Trace gases are all those other than N 2 & O 2. Small in amount, but large effects (ozone layer, greenhouse effect, smog)

4 Structure and Composition of the Atmosphere Trace gases are emitted at the surface, and get mixed through convection and atmospheric circulation Natural emissions include: hydrocarbons from growing plants, and CO 2 from respiration CO 2, CO, C 2 H 6, HCN, from wild fires H 2 O, CO 2, SO 2, from volcano eruptions Photochemical production of ozone in the stratosphere (and troposphere from lightning) oceanworld.tamu.edu

5 Structure and Composition of the Atmosphere Anthropogenic emissions include: Fossil fuel burning for electricity, transport, and industry (CO 2, CH 4, C 2 H 6, NO, NO 2, ) CO 2, CO, C 2 H 6, HCN, from biomass burning (e.g. deforestation) CH 4, N 2 O, NO x, NH 3, from agriculture oceanworld.tamu.edu

6 Structure and Composition of the Atmosphere Ozone (O 3 ) is a special case not emitted directly Stratospheric ozone ( ozone layer ) is created by UV rays breaking up the O 2 molecules:

7 Structure and Composition of the Atmosphere Ozone (O 3 ) is a special case not emitted directly Tropospheric ozone is created by photochemical reactions involving NO x, CO, and organic compounds In the presence of CO and NO: CO + OH + O 2 CO 2 + HO 2 HO 2 + NO OH + NO 2 NO 2 + hn + O 2 NO + O 3

8 Structure and Composition of the Atmosphere Ozone (O 3 ) is a special case not emitted directly Tropospheric ozone is created by photochemical reactions involving NO x, CO, and organic compounds Damage to natural ecosystems, crops, and human health Causes global warming Most areas of Ontario are still above the Canada wide standard for ozone (Air Quality in Ontario Report for 2010)] healthy inflamed

9 movie Climate Change

10 Climate Change Atmospheric CO 2 concentration is higher than ever due to burning of fossil fuels CO 2 absorbs infrared radiation, which warms the lower atmosphere

11 Effect of Aviation on Climate Change

12 Aircraft Emissions Aircraft emissions arise from the burning of fossil fuels, and breakdown of N 2 from the heat of the engines Since planes fly in the upper troposphere/ lower stratosphere (UTLS), the effects of CO 2, NO x, and O 3 on global warming are enhanced Globally: 180 Tg fuel burn, 2.7 Tg NO x, 92% in northern hemisphere, 71% above 8 km altitude

13 Effects of Aviation on Climate Change

14 Effects of Aviation on Climate Change Lee et al. (2010) DEPARTMENT OF ENGINEERING Regarding aircraft emissions, NO x -O 3 warming is about the same as CO 2 warming CO 2 from history of aviation O 3 from past few weeks S. Barrett (MIT)

15 Effects of Aviation on Climate Change Temporal sensitivity of O 3 to aircraft NO x Spatial variability of sensitiviti Tropospheric O 3 sensitivity to NO x at 11 km altitude (kg/kg) Seasonal and spatial effects on aircraft O 3 production were modelled Modern planes are more fuel efficient (less CO 2 ), but emit more NO x (more O 3 ) due to the increased combustion temperature in the high pressure engines S. Barrett (MIT)

16 Effect of Aviation on the Ozone Layer

17 Effect of Aviation on the Ozone Layer The ozone layer gets depleted due to chemical reactions with NO x, HO x, and ClO x Controls on chlorine species (Montreal Protocol), but not on nitrogen species

18 Effect of Aviation on the Ozone Layer Aircraft emit NO x at an altitude at which it can directly go to work on statospheric O 3 Aircraft also emit aerosols on which clouds can form O 3 destruction chemistry occurs more efficiently on cloud droplets

19 Effect of Aviation on Air Quality

20 Effect of Aviation on Air Quality First environmental concerns about aircraft emissions were focused on local air quality Led to the introduction of the Clean Air Act in the USA and then to International Standards for fuel venting and emissions of CO, NOx, unburned fuel, and smoke below 3000 ft (ICAO, 1981)

21 Effect of Aviation on Air Quality Since air quality is an issue near the surface, aviation currently has little effect E.g. for Toronto O 3 :

22 Effect of Aviation on Air Quality But aviation emissions are forecast to double or triple by the mid-21 st century, which could increase it s effect on air quality Air quality near airports is also a concern with large emissions from taxiing, take off and landing airplanes, refueling, and ground traffic to and from the airport The Greater Toronto Airport Authority has introduced a number of policies to reduce emissions Reducing idle time for planes waiting to take off Support transit enhancement proposals (e.g. Eglinton light rail line) Energy conservation in the airport

23 Effect of Aviation on Atmospheric Composition Aviation has been growing faster than any other source of GHG. Between 1990 and 2006 GHG emissions from aviation increased by 87% improvements to fuel efficiency are eclipsed by the increase in air traffic volume Per person, per km, air travel CO 2 emissions are on average similar to a four-seat car with one person on board, but for much longer trips so total emissions are high NO x emissions in the upper troposphere make O 3 (a GHG) more efficiently than NO x emissions at the surface

24 How We Measure Atmospheric Composition

25 How we measure atmospheric composition In situ Sondes Lidar Satellites Ground-based spectrometers Aircraft

26 Measuring with ground-based FTIR University of Toronto Atmospheric Observatory (TAO, o N, o W) Environment Canada s Centre for Atmospheric Research Experiments (CARE, o N,79.78 o W) TAO is an NDACC (Network for Detection of Atmospheric Composition Change) site We can measure up to 20 trace gases with FTIR 26

27 Measuring atmospheric composition from aircraft Aircraft measurements provide an opportunity to take in situ measurements (which are very precise) at multiple altitudes throughout the atmosphere

28 Measuring atmospheric composition from aircraft

29 Measuring atmospheric composition from aircraft

30 Measuring atmospheric composition from aircraft MOZAIC (Measurement of Ozone and Water Vapour on Airbus inservice Aircraft) has done routine aircraft in-situ measurements since 1994 Measures vertical profiles of O3, CO, H2O on takeoff and landing, and UTLS measurements at 9-12km during inter-continental flight Cammas, J.-P., Université de Toulouse

31 Effect of Climate Change on Aviation

32 Effect of climate change on aviation A resent study examined the effect of climate change on turbulence in the North Atlantic flight corridor where 600 plane fly between North America & Europe daily. Their simulation predicts by 2050, the airspace containing significant turbulence will have doubled, the strength of turbulence will increase by 10-40%, and the frequency of turbulence will increase by % Chestney, Nina, Reuters, 2013

33 Conclusions Trace gases make up <1% of the atmosphere but affect the radiative balance of the earth, and affect all living creatures Anthropogenic activity causes climate change, stratospheric ozone depletion, and smog Aircraft emissions have an enhanced effect on global warming, and the ozone layer as they are emitted in the UTLS