Unmanned aerial vehicle observations of the vertical distribution of particulate matter and sulfur dioxide at a regional background site in northwest China

Abstract

The vertical measurements of atmospheric pollutants are essential for understanding various atmospheric chemical processes and the transmission of air pollutants. Herein, we measured particulate matter (PM) and SO2 concentrations using a six-axis unmanned aerial vehicle (UAV) equipped with portable monitors at the Akedala Background Station in northwest China from the surface to 500 m above the ground level. Twelve-day measurements (68 flights) were conducted from July 13 to 24, 2020. Results showed that the UAV platform could effectively capture the vertical distribution of PM and SO2. During the observation period, the concentrations of PM1, PM2.5, and PM10 in Akedala were 0.1–11.8, 0.2–13.0, and 0.2–21.7 μg/m3, respectively, and SO2 concentrations ranged between 0.1 and 29.4 ppb. The weather condition and backward trajectory indicated that the air mass affecting the station mainly originates from Kazakhstan, southern Russia, and northern Xinjiang.PM and SO2 can be classified into different types based on their vertical profile characteristics, where SO2 mainly showed an incremental distribution, which may be related to the long-distance transport of pollutants. PM mainly showed unimodal distributions, which may be related to the inverse temperature phenomenon and transport of pollutants. Remote sensing data and MIX emission inventory showed the presence of dot emission areas in southern Russia, Kazakhstan, and northern Xinjiang cities, which made important contributions to the air pollutants in Akedala.