© University of Reading 2008www.reading.ac.uk RMetS Conference June 2011 Towards a mitigation of the climate impact of aviation by climate-optimised routing Emma Irvine Keith Shine, Brian Hoskins (University of Reading)

Radiative forcing resulting from aviation emissions Timescale: Decades Months Years Months Hours Aviation emissions contribute 3.5% (range 2-14%) of total anthropogenic forcing, including non-CO 2 effects (Lee et al., 2009)

Climate impact of aviation Lee et al (2009)From Laura Wilcox Growth in global CO 2 emissionsAltitude of aircraft emissions 1.Not just from CO 2 2.Disproportionate to amount of emissions 3.Will increase – aviation sector growing at 5% per year 4.Industry targets: 50% reduction in net CO2 emissions by km

Minimize the climate impact of the aircraft’s emissions Traditional constraints: time, cost, fuel 4 PROs:CONs: Low-costAir-traffic control constraints Quick to implementHigh volume of air traffic in N. Atlantic Does not rely on technological developments Climate-optimal aircraft routing New York London

Climate optimal routing in the EU REACT4C project Weather situation Calculate climate impact C(x,y,z,t) Find route minimising C 5 READING/UKMO DLR/CICERO/ MMU/AQUILA EUROCONTROL Calculate for each flight across the north Atlantic (~300 per direction) Aircraft specifications: current operational fleet future green aircraft (AIRBUS) Dec 2009 eastbound westbound

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

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

Winter weather types are characterised by the jet 1.Strong zonal jet 2.Strong tilted jet 3.Weak tilted jet 4.Strong confined jet Eastbound Westbound Irvine et al., 2011, Met. Apps., submitted

Climate impact varies by weather type and route direction CO 2 Contrails Jet classification: S=strong, W=weak, Z=zonal, T=tilted, C=confined We define indicative proxies for the climate impacts: CO 2 route time Contrailsdistance contrailing NO x route time at each latitude H 2 Oroute time in stratosphere

Probability of making a persistent contrail along a route at different flight levels 10 Cruising at higher altitude decreases contrails (e.g. Fichter, 2009) Not true if you look at individual weather types!

Summary Climate-optimal routing is a potential method of mitigating aircraft climate impact, and is being investigated by the REACT4C project For the North Atlantic, distinct weather types are identified, these are characterised by the jet stream strength and location The climate impact of aircraft emissions varies with weather type, and altitude

Thank you!

Define typical weather situations Calculate Radiative forcing from contrails, CO2, 03 Combine to make climate cost function Find optimal route minimising the climate cost function Determine controller workload for these routes Simulate flights to get flight trajectories Calculate the total climate impact The REACT4C Modelling Chain Green aircraft AIRBUS DLR/CICER O READING/UKMO EUROCONTR OL

The North Atlantic flight corridor > 300 flights per day in each direction 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) Dec 2009 Figure from Laura showing global flight tracks eastbound westbound From Laura Wilcox

How can we reduce the impact of aviation on climate? New technologies –Cleaner fuels, e.g. gas-to-liquid, biofuels, hydrogen –More efficient engines –Resulted in large gains in fuel efficiency over the last 40 yrs Existing technologies –Improved air-traffic management procedures e.g. less holding, better airspace co-ordination (SESAR) –Continuous descent approach (e.g. Ren et al (2010)) –Climate-optimised routing Aircraft powered by algae biofuel (EADS)

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