Capturing the vertical distribution of near-highway nitrogen dioxide using UAV-based measurements

This pilot study evaluates the use of Uncrewed Aerial Vehicles (UAVs) to capture variations in the transport and dispersion of nitrogen dioxide (NO2) under different atmospheric dispersion conditions. The vertical distribution of NO2 concentration was observed using an unmodified handheld electrochemical gas sensor mounted onboard a UAV, beside a major Canadian highway. Observations were taken in both poor and good dispersion conditions, as determined by the Atmospheric Dispersion Index and Ventilation Index. Results reveal atmospheric stability has a significant impact on the vertical profiles of NO2. The low wind speeds and limited vertical mixing experienced during poor dispersion conditions resulted in concentrations increasing with altitude, contrasting with the stable NO2 concentrations observed during good dispersion conditions. Statistical analysis reveals significant differences between ground-level measurements and simultaneous UAV-based readings at higher altitudes during poor dispersion, suggesting the influence of regional emissions accumulating due to poor mixing. These preliminary results demonstrate the potential for UAV-based measurements in air quality management. The ability to capture nuanced dynamics such as the accumulation of regional emissions is critical when studying pollutions events such as wildfires.