Tradeoff Between Contrail Reduction and Emissions in United States National Airspace

Abstract

This paper describes a class of strategies for reducing persistent contrail formation with the capability of trading off between contrails and aircraft-induced emissions. The concept of contrail-frequency index is defined and used to quantify the contrail activities. The contrail-reduction strategies reduce the contrail-frequency index by altering aircraft's cruising altitude with consideration to extra emissions. The strategies use a user-defined factor to trade off between contrail reduction and extra emissions. The analysis shows that contrails can be reduced with extra emissions and without adding congestion to airspace. For a day with high contrail activities, the results show that the maximal contrail-reduction strategy can achieve a contrail reduction of 88%. When a tradeoff factor is used, the strategy can achieve less contrail reduction while emitting less emissions compared to the maximal contrail-reduction strategy. The user-defined tradeoff factor provides a flexible way to trade off between contrail reduction and extra emissions. Better understanding of the tradeoffs between contrails and emissions and their impact on the climate need to be developed to fully use this class of contrail-reduction strategies. The strategies provide a starting point for developing operational policies to reduce the impact of aviation on climate.

Application of Climate Impact Metrics to Civil Tiltrotor Design

“…Also, strategies are currently being developed to redu ce the effects of AIC by rerouting aro und areas in the atmosphere prone to ai rcraft contrail s, so future aircraft may have significantly reduced climate impacts due to AIC. 37 Both the discount rate ' used for computing ATR and the choice of reference engine for NO x emissions affect the results of the metric computations. F igmes 9a and b show these effects without including AIC.…”

Evaluation of Aircraft Contrails using Dynamic Dispersion Model

“…7,8 The results can be used to measure the long-term climate impact of the aviation-induced linear contrails and design the aircraft operation strategies to reduce the contrail environmental impact (e.g. references 18,19 ).…”

Evaluation of Contrail Reduction Strategies Based on Aircraft Flight Distances

“…11. That strategy for reducing the persistent contrail formations is to minimize contrail frequency index by altering the aircraft's cruising altitude.…”

“…11. The contrail models use atmospheric temperature and humidity data retrieved from the Rapid Updated Cycle (RUC) data, provided by the National Oceanic and Atmospheric Administration (NOAA).…”

“…These restrictions generally imply more fuel burn, thus more emissions, and add congestion to the already crowded airspace at lower altitudes. Sridhar 10 and Chen 11 proposed contrail reduction strategies by altering an aircraft's cruising altitude in a fuel-efficient way. The strategies were designed without increasing congestion in the airspace.…”