Drone-based vertical profiling of particulate matter size distribution and carbonaceous aerosols: urban vs. rural environment

Abstract

The study presents drone-based measurements to investigate the seasonal vertical variability of equivalent black carbon (eBC) mass and particle number concentrations (PNC) at a rural and urban site in the Czech Republic. Vertical profiles of eBC were measured using a micro-aethalometer, while PNC was measured using an optical particle counter. Drone-based eBC measurements closely matched reference aethalometers placed at both ground level and at 230 m of a tower when using a humidity control mechanism. Without dryer, eBC mass concentration was overestimated by 276 % in summer and 285 % in winter, but uncertainties were reduced to under 10 % with drying. These findings highlight the importance of humidity control for accurate aerosol measurements, especially for eBC. The study also revealed a decrease in eBC and PNC with height at the rural site during both summer and winter, with seasonal differences in the altitude where this decrease began. Elevated eBC concentrations in winter were due to increased atmospheric stability and combustion-related fine particles. At the urban site, concentrations in summer were uniform with height (4 to 100 m above ground level (a.g.l.)) but gradually decreased with height during winter. Furthermore, the study investigated changes in the vertical distribution of eBC and PNC during a high pollution event at the urban site, influenced by long-range transport. Our findings confirm the effectiveness of drones in capturing vertical variations of air pollutants, offering results on the dynamics between local emissions, atmospheric stability, and long-range transport and suggesting the necessity of measuring vertical concentration profiles to support air quality management strategies.