Supersonic transport aircraft emissions: primary atmospheric region affected Exhaust plumes from supersonic transport aircraft predominantly impact which atmospheric layer with respect to pollution and ozone chemistry?

Introduction / Context:
High-altitude aviation emissions can perturb atmospheric chemistry beyond the surface layer. Supersonic transports (SSTs) cruise at altitudes overlapping the lower stratosphere, where ozone formation and destruction cycles are sensitive to NOx and other exhaust species.

Given Data / Assumptions:

• SST cruise altitudes often approach or enter the lower stratosphere.
• Emissions include NOx, H₂O vapour, particles, and trace species.

Concept / Approach:
The stratosphere contains the ozone layer. Injected NOx catalytically converts ozone to O₂, and added water vapour can influence polar stratospheric cloud chemistry. Because vertical mixing is slower than in the troposphere, residence times and impacts can be significant relative to emission mass.

Step-by-Step Solution:

Verification / Alternative check:
Studies of historical SST concepts (e.g., Concorde) focused on stratospheric NOx and ozone impacts, not tropospheric air quality.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming all aircraft emissions primarily affect ground-level air quality; altitude matters for chemistry and lifetimes.

Final Answer:
stratosphere