Effects of plume‐scale versus grid‐scale treatment of aircraft exhaust photochemistry

This is a study to examine the impact of modeling photochemistry from aircraft emissions in an expanding plume versus at the grid scale in an atmospheric model. Differences in model treatments for a single flight occurred at all altitudes during takeoff, cruise, and landing. After 10 h, the plume treatment decreased grid‐scale ozone production by 33%, methane destruction by 30%, and carbon monoxide destruction by 32% at cruise altitude compared with the grid‐scale treatment. The plume treatment changed the odd nitrogen partitioning by ~10%. For multiple overlapping flights at cruise altitude, final ozone, methane, and carbon monoxide perturbations decreased by 77, 68, and 74%, respectively, compared with the grid‐scale treatment. Enhanced mixing with ambient air reduced the plume‐scale and grid‐scale differences. The persistent differences in photochemical activity indicate that individual plume treatment should be incorporated into 3‐D modeling studies.