Mitigating the Climate Forcing of Aircraft Contrails by Small-Scale Diversions and Technology Adoption
Abstract
Aircraft contrails form under favourable atmospheric conditions with high humidity and low temperatures. Over time, linear contrails spread and mix with other contrails and natural cirrus, transitioning into contrail-induced cirrus which its climate impact could be comparable to aircraft CO2 emissions but with a large uncertainty.
In this research, we aim to: (i) quantify the uncertainty in the climate impact of contrails for the first time, accounting for the uncertainties in meteorology and aircraft black carbon (BC) particle number (PN) emissions; and (ii) propose potential solutions to reduce the climate impact of contrails with minimum disruptions to Air Traffic Management (ATM) procedures. This is achieved by utilising a numerical Monte Carlo method on the CoCiP contrail model, coupled with inputs of air traffic data over Japan (CARATS Open Data), meteorological data (ECMWF ERA5 HRES and EDA), an aircraft fuel consumption model (BADA 3), and an aircraft BC PN emissions model (Fractal Aggregates Model). Over the 6-weeks of aircraft activity data that is available, on average, 17.8% [17.2%, 18.4%] of flights form contrails with an average age of 3.24 [3.09, 3.36] hours, the net radiative forcing and energy forcing (EF) are 1.74 [1.21, 2.56] W m-2 and 5.38 [3.85, 6.66] J respectively. Although previous studies recommended a fleet-wide diversion of flights to avoid contrail formation, this might not be necessary because only 2.19% [1.97%, 2.45%] of flights contribute to 80% of the total contrail EF. Instead, a small-scale diversion strategy of modifying the cruising altitude of 1.7% of flights by ±2000 feet could reduce the contrail EF by up to 59.3% [52.4%, 65.6%], at the expense of an average fuel penalty of 0.71% [0.36%, 1.10%] per flight. Over the longer term, a fleet-wide adoption of new technologies such as the double annular combustor engine, of which the average BC PN emissions is 76% lower than conventional engines, could reduce the contrail age and EF by 22.5% [15.6%, 27.9%] and 68.6% [45.0%, 82.0%] respectively. Finally, a combination of both methods (including the diversion strategy) could theoretically reduce the contrail EF by up to 91.8% [88.6%, 95.8%].- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A32A..06T
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0321 Cloud/radiation interaction;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 6344 System operation and management;
- POLICY SCIENCES & PUBLIC ISSUES