© University of Reading 2008 www.reading.ac.uk

RMetS Conference June 2011

Towards a mitigation of the climate impact of aviation by climate-optimised routingEmma Irvine

Keith Shine, Brian Hoskins (University of Reading)

Radiative forcing resulting from aviation emissions

Timescale:

Decades

MonthsYears

Months

Hours

Hours

• Aviation emissions contribute 3.5% (range 2-14%) of total anthropogenic forcing, including non-CO2 effects (Lee et al., 2009)

Climate impact of aviation

Lee et al (2009) From Laura Wilcox

Growth in global CO2 emissions Altitude of aircraft emissions

1. Not just from CO2

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 2050

9-12km

• Minimize the climate impact of the aircraft’s emissions

• Traditional constraints: time, cost, fuel

4

PROs: CONs:

Low-cost Air-traffic control constraints

Quick to implement High 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

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 2010 26 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

EASTBOUND WESTBOUND

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 byweather type and route direction

CO2 Contrails

Jet classification: S=strong, W=weak, Z=zonal, T=tilted, C=confined

We define indicative proxies for the climate impacts:

• CO2 route time• Contrails distance contrailing• NOx route time at each latitude• H2O route 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!

e.a.irvine@reading.ac.uk

www.react4c.eu

The REACT4C Modelling Chain

AIRBUS

DLR/CICERO

READING/UKMO

EUROCONTROL

The North Atlantic flight corridor

• > 300 flights per day in each direction

• 6.5% total aviation CO2 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 impactof 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)