Exploring the feasibility of climate-optimised flight routing

1. Exploring the feasibility of climate-optimised flight routing Emma Irvine, Keith Shine, Brian Hoskins Meteorology Department, University of Reading Contact: e.a.irvine@reading.ac.uk

2. Outline • Motivation for climate-optimised routing • The climate impact of aviation emissions • The REACT4C project • Results: Weather and aircraft routing in the N Atlantic • The role of the jetstream and NAO • Identifying weather types for the North Atlantic • Does the climate impact of the emissions vary by type? • Conclusions and future directions

3. Radiative forcing resulting from aviation emissions Timescale Weather Less relevant Decades Months Hours More relevant • Aviation emissions contribute 3.5% (range 2-14%) of total anthropogenic forcing, including non-CO2 effects (Lee et al., 2009)

4. Motivation Climate impact is not just from CO2 Climate impact is disproportionate to quantity of emissions Climate impact will increase – sector growing at 5% per year Aviation Industry targets: 50% reduction in net CO2 emissions by 2050: technological and operational measures Growth in global CO2 emissions Altitude of aircraft emissions 9-12km Lee et al (2009) From Laura Wilcox

5. Climate-optimal aircraft routing • Minimize the climate impact of the aircraft’s emissions • Traditional constraints: time, cost, fuel New York London

6. Climate-optimal aircraft routing • North Atlantic Tracks • Minimum separations: • 1° latitude between tracks • 1000 ft vertical • 10 min along-track • Specified twice daily by ATC based on airline requirements: • Eastbound at night • Westbound during day New York London westbound eastbound Dec 2009

7. Climate impact varies with route location, weather and season 18 February 2010 26 January 2010 contrails Flight level tropopause Flight entirely in stratosphere produces no contrails Flight mostly in troposphere produces persistent contrails

8. EU REACT4C Project • GOAL: Assess the feasibility of reducing emissions • of trans-Atlantic flights through climate-optimal routing • EU FP7 medium-scale collaborative project • NOT implementing or developing capability to implement! • Results due END 2012 2006 aircraft emissions (Laura Wilcox) • North Atlantic Flight Corridor • 6.5% total aviation CO2 emissions • 97% emissions released above 7km (Wilkerson, 2010) Website: www.react4c.eu

9. Climate optimal routing in the EU REACT4C project (1) • Calculate the climate-optimal route for separately for each flight across the north Atlantic (~300 per direction per day) • Aircraft specifications: • current operational fleet • future green aircraft (AIRBUS) DLR/CICERO/ MMU/AQUILA READING/ MET OFFICE EUROCONTROL

10. Climate optimal routing in the EU REACT4C project (2) EUROCONTROL • Not all aircraft will be able to fly their climate-optimal route • Iterate to find a combination of climate-optimal and sub-climate optimal trajectories which results in: • Reduced total climate-impact of NAFC traffic compared to a control scenario (minimal fuel use) • An acceptable workload for ATC • Answer will be different for each weather situation!

11. Defining typical weather patterns over the north Atlantic Paper in review: Irvine et al., 2011, Characterising north Atlantic weather patterns for climate optimal aircraft routing, Meteorological Applications

12. Time-optimal route latitude is related to the jet stream latitude EASTBOUND WESTBOUND Jet stream latitude is related to NAO and EA patterns (Woollings et al. 2010)

13. The jet stream latitude is related to the North Atlantic Oscillation +ve NAO +ve = northerly jet stream NAO -ve = southerly jet stream -ve ERA-Interim meteorological re-analysis data from 1989-2010 From: http://www.ldeo.columbia.edu/res/pi/NAO/

14. Winter weather types are characterised by the jet Eastbound Westbound • Strong zonal jet • Strong tilted jet • Weak tilted jet • Strong confined jet Irvine et al., 2011, Met. Apps., submitted

15. Winter weather types are characterised by the jet Eastbound Westbound • Strong zonal jet • Strong tilted jet • Weak tilted jet • Strong confined jet Irvine et al., 2011, Met. Apps., submitted

16. Climate impact varies byweather type and route direction • We define indicative proxies for the climate impacts • (other REACT4C partners will do detailed calculations for): • CO2 route time • Contrails distance contrailing • NOx route time at each latitude • H2O route time in stratosphere CO2 Contrails Jet classification: S=strong, W=weak, Z=zonal, T=tilted, C=confined

17. Probability of making a persistent contrail along a route at different flight levels • Cruising at higher altitude decreases contrails (e.g. Fichter, 2009) • Not true if you look at individual weather types!

18. Summary Is climate optimal routing a feasible way of reducing emissions of trans-Atlantic flights? Wait and see: REACT4C results due 2012 • For the North Atlantic, distinct weather types are identified, each associated with different winds and time-optimal routes • Both the route location and climate impact are determined by the meteorology • The climate impact relates to the route length (CO2), latitude (O3), height relative to the tropopause (H2O) and regions of ice-supersaturation (contrails) • The climate-optimisation strategy depends on the relative weighting of the climate impacts

19. Future Directions • Currently: What weather conditions cause contrail-supporting regions? • Planning stage: Can we predict the occurrence of contrail-supporting regions with sufficient accuracy at timescales required by operational flight planning? • REACT4C2 ? (depends on results from REACT4C)

20. Thank you! Information from: e.a.irvine@reading.ac.uk www.react4c.eu