© university of reading 2008 rmets conference june 2011 towards a mitigation of the climate impact...
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© 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)
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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)
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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
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• 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
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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
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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
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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)
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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
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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
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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!
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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
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The REACT4C Modelling Chain
AIRBUS
DLR/CICERO
READING/UKMO
EUROCONTROL
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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
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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)