Potential Impacts of Supersonic Aircraft Emissions on Ozone and Resulting Forcing on Climate: An Update on Historical Analysis

Abstract

The overall demands by the public for air travel, the aspiration for more intercontinental travel, and the desire for shorter flight times have all increased in the past few decades. As a result, various companies and organizations around the world have been reconsidering development of supersonic aircraft for the business jet and commercial airline markets (e.g., NASA, Aerion, Spike Aerospace, and Boom Technology). Commercial fleets of supersonic transport (SST) aircraft were first considered in the 1970s (Climate Impact Assessment Program, 1975) and then again in the 1990s (Kawa et al., 1999). The cruise altitudes flown by supersonic aircraft depends on the design and speed of the aircraft with faster aircraft flying at higher altitudes. Supersonic aircraft would fly at higher altitudes than the current fleet of subsonic aircraft, with their emissions primarily being in the stratosphere. With a potential range of cruise altitudes from 13 to 23 km, the majority of emissions from supersonic aircraft would occur in the stratosphere and would have longer atmospheric lifetimes than the emissions occurring from subsonic aircraft that primarily fly in the troposphere. Supersonic aircraft emissions can be

Stratospheric Ozone and Climate Forcing Sensitivity to Cruise Altitudes for Fleets of Potential Supersonic Transport Aircraft

“…PORT utilizes the radiation code from CAM4 (Gent et al, 2011) and calculates the changes in the stratospheric-adjusted radiative forcing under the fixed dynamical heating condition (Fels et al, 1980). A more detailed description for WACCM and PORT can be found in Zhang et al, 2021. Simulations in this study are branched off from the existing Chemistry Climate Model Initiative (CCMI) simulations for the model years 2040-2052 (Morgenstern et al, 2017) and outputting the high frequency meteorological fields, sea surface temperatures, and sea ice for the same time period. All the simulations used in this study are running with the specified dynamics (SD) mode (Lamarque et al, 2012) using the derived information from the CCMI runs.…”

“…Several more recent studies have evaluated the potential environmental effects of supersonic exhaust on the atmosphere for different specific aircraft designs (e.g., Pitari et al., 2004; Pitari & Mancini, 2001; Grewe et al., 2007, 2010; Zhang et al., 2021). Like the earlier studies, these studies have demonstrated the importance of supersonic NOx and H 2 O emissions in the distribution of stratospheric ozone abundance and on climate.…”

“…A cross-over point in the ozone chemical production and destruction induced from supersonic aircraft emissions can be found in the lower stratosphere in some of the earlier modeling studies (e.g., Dameris et al, 1998;Grooβ et al, 1998;Zhang et al, 2021), but the altitude where this cross-over point occurs is not consistent in the different modeling studies (Grewe et al, 2007). Four models were used in Grewe et al (2007) and only two of the models simulated a cross-over point in the lower stratosphere.…”

“…Like the earlier studies, these studies have demonstrated the importance of supersonic NOx and H 2 O emissions in the distribution of stratospheric ozone abundance and on climate. Zhang et al (2021) revisited the potential ozone and climate impacts from the fleet of supersonic aircraft proposed for the earlier assessments- Kawa et al (1999) and Penner et al (1999) using a state-of-art climate-chemistry model to update the understanding of potential supersonic aircraft effects, while examining stratospheric ozone sensitivity to different NOx emission levels. Previous studies have also shown that the stratospheric ozone effects from fleets of supersonic commercial aircraft are sensitive to cruise altitude (e.g., Baughcum et al, 2003;Grewe et al, 2007Grewe et al, , 2010Wuebbles, Dutta, Jain & Baughcum, 2003;Wuebbles, Dutta, Patten & Baughcum, 2003).…”

“…This difference can be attributed to different representations in chemical and transport processes in these models. Using a current state-of-the-art climate-chemistry model, Zhang et al (2021) found that the cross-over point occurs at altitudes around 17 km over the Northern Hemisphere (NH) mid-latitudes in the lower stratosphere (see Figure 5a). Ozone destruction can be found above this cross-over point all the way up to the middle and upper stratosphere.…”