A mitigation strategy for commercial aviation impact on NO_x-related O₃ change

An operational mitigation strategy for commercial aircraft impact on atmospheric composition, referred to as the turboprop replacement strategy (TRS), is described in this paper. The global air traffic between 2005 and 2011 was modeled with the TRS in which turbofan powered aircraft were replaced with nine chosen turboprop powered aircraft on all routes up to 1700 nautical miles (NM) in range. The results of this TRS double the global number of departures, as well as global mission distance, while global mission time grows by nearly a factor of 3. However, the global mission fuel and the emissions of aviation CO₂, H₂O, and SO_x remain approximately unchanged, and the total global aviation CO, hydrocarbons (HC), and NO_x emissions are reduced by 79%, 21%, and 11% on average between 2005 and 2011. The TRS lowers the global mean cruise altitude of flights up to 1700 NM by ~2.7 km which leads to a significant decrease in global mission fuel burn, mission time, distance flown, and the aircraft emissions of CO₂, CO, H₂O, NO_x, SO_x, and HC above 9.2 km. The replacement of turbofans with turboprops in regional fleets on a global scale leads to an overall reduction in levels of tropospheric O₃ at the current estimated mean cruise altitude near the tropopause where the radiative forcing of O₃ is strongest. Further, the replacement strategy results in a reduction of ground-level aviation CO and NO_x emissions by 33 and 29%, respectively, between 2005 and 2011.