Towards Climate-Optimised Routing of Trans-Atlantic Flights. Emma Irvine Keith Shine, Brian Hoskins (University of Reading) Bob Lunnon (Met Office)

Transcription

1 Towards Climate-Optimised Routing of Trans-Atlantic Flights Emma Irvine Keith Shine, Brian Hoskins (University of Reading) Bob Lunnon (Met Office)

2 Outline Motivation for climate-optimised routing The climate impact of aviation emissions The REACT4C project North Atlantic Weather types Relationship between time-optimal route and jetstream Identifying weather types for the North Atlantic A first look at the climate impact for each weather type A thought experiment: contrails

3 Aviation contribution to UK carbon dioxide (CO 2 ) emissions

4 Aviation and Climate Change Growth in global CO 2 emissions Altitude of aircraft emissions Lee et al (2009) From Laura Wilcox Aviation has been growing at 5% per year Aviation emissions contribute 3.5% (range 2-14%) of total anthropogenic forcing, including non-co 2 effects (Lee, 2009)

5 Radiative forcing resulting from aviation emissions Timescale: Decades Months Years Months Hours Hours Lee et al (2009)

6 Reducing Emissions from Aviation by Changing Trajectories 4 the benefit of Climate For a given set of weather situations design minimum climate impact alternatives to the traditional quickest least fuel cheapest routes, subject to air traffic constraints Focus on flights between Europe and north America Funded under EU 7 th Framework Programme Project partners: DLR, MMU, Reading, Aquila, CICERO, EUROCONTROL, Met Office, Airbus

7 The North Atlantic flight corridor > 300 flights per day in each direction From Laura Wilcox 6.5% total aviation CO 2 emissions (Wilkerson, 2010) 97% emissions released above 7km Large daily variation in optimal route location (quickest route at 250hPa) westbound Dec 2009 eastbound

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

9 WEATHER TYPES AND CLIMATE IMPACTS

10 Data and Methods Time-optimum route data for London - New York Data for winters (DJF) , , Assumptions: Constant flight level of 250 hpa (34,000ft) Constant airspeed of 250m/s (550mph) Eastbound flights depart 0000 UTC; westbound flights depart 1200 UTC Meteorological data is ERA-Interim: , 0.7 grid 250hPa jetstream latitude calculated following Woollings et al (2010)

11 Optimal route latitude is related to the 250hPa jet stream latitude... EASTBOUND WESTBOUND

12 ...the jet stream latitude is related to large-scale patterns Jet latitude mean and standard deviation Jet latitude skewness Winter mean North Atlantic Oscillation (NAO) index Winter mean East Atlantic (EA) index

13 Identifying winter weather types Anomalies of 250 hpa geopotential height are projected onto the NAO and EA patterns for winter (DJF): EA NAO Contours = Z250 anomalies, arrows = climatological mean wind Derived from indices calculated at 500hPa, from

14 Identifying winter weather types The weather types are obtained by splitting the NAO-EA phase space to obtain robust, frequently occurring patterns: EA NAO Contours = Z250 anomalies, arrows = climatological mean wind Derived from indices calculated at 500hPa, from

15 Winter weather types Eastbound Westbound 1. Strong zonal jet 2. Strong tilted jet 3. Weak tilted jet 4. Strong confined jet

16 Indicative proxies for individual climate impacts CO 2 : route time Contrails: distance contrailing: Rh i > 100% and T < 233K (Schumann, 1996) H 2 O: time in stratosphere Potential vorticity > 2PVU O 3 : latitude O 3 radiative forcing per unit NO x emission From Christine Fromming, DLR

17 Route time (hrs) Time in stratosphere Climate impact by type for eastbound and westbound routes CO 2 O 3 1-SZ 2-ST 3-WT 4-SC Type H 2 O 1-SZ 2-ST 3-WT 4-SC Type Distance contrailing Ozone Metric SZ 2-ST 3-WT 4-SC Type Contrails 1-SZ 2-ST 3-WT 4-SC Type Jet classification: S=strong, W=weak, Z=zonal, T=tilted, C=confined

18 THOUGHT-EXPERIMENT: CONTRAILING

19 Thought-experiment: To contrail or not to contrail? New York London CLIMATE COST contrail x-section CO 2 H 2 O O 3

20 Thought-experiment: To contrail or not to contrail? 1. No avoiding action; make a contrail New York London CLIMATE COST contrail x-section CO 2 H 2 O O 3

21 Thought-experiment: To contrail or not to contrail? 2. Change direction to avoid contrailing New York London CLIMATE COST contrail x-section CO 2 H 2 O O 3

22 Thought-experiment: To contrail or not to contrail? 3. Change altitude to avoid contrailing: UP New York London CLIMATE COST contrail x-section CO 2 H 2 O O 3

23 Thought-experiment: To contrail or not to contrail? 3. Change altitude to avoid contrailing: DOWN New York London CLIMATE COST contrail x-section CO 2 H 2 O O 3

24 Thought-experiment: To contrail or not to contrail? The answer depends on how the different climate impacts are weighted! New York London CLIMATE COST? contrail x-section??? CO 2 H 2 O O 3

25 Summary For the North Atlantic, distinct weather types are identified, each associated with different winds and therefore different time-optimal routes Both the route location and climate impact are determined by the meteorology The climate impact relates to the route length (CO 2 ), latitude (O 3 ), height relative to the tropopause (H 2 O) and regions of ice-supersaturation (contrails) The climate-optimisation strategy depends on the relative weighting of the climate impacts

26 Thank you!

27 The REACT4C Modelling Chain Define typical weather situations Calculate the total climate impact Calculate Radiative forcing from contrails, CO 2, 0 3 Simulate flights to get flight trajectories Combine to make climate cost function Determine controller workload for these routes Find optimal route minimising the climate cost function