Vertical Characteristics of Winter Ozone Distribution within the Boundary Layer in Shanghai Based on Hexacopter Unmanned Aerial Vehicle Platform

Qian Chen,Xiaobing Li,Zhongren Peng,Dongsheng Wang,Bai Li,Hongdi He,Ruifeng Song

doi:10.3390/su11247026

Abstract

Ozone is an important secondary air pollutant and plays different significant roles in regulating the formation of secondary organic aerosols. However, the characteristics of winter vertical ozone distributions have rarely been studied. In the winter of 2017, field experiments were performed in Shanghai, China using hexacopter unmanned aerial vehicle (UAV) platforms. The vertical profiles of ozone were obtained from 0–1200 m above the ground level. Results show that the UAV observations were reliable to capture the vertical variations of ozone. Vertical ozone profiles in the winter are classified into four categories: (1) well-mixed profile, (2) altitudinal increasing profile, (3) stratification profile, and (4) spike profile. Results show that although the average surface ozone level was relatively low, strong ozone variability and high ozone concentrations occurred at the upper air. The maximum observed ozone concentration was 220 ppb. In addition, using meteorological profiles and backward trajectories, we found that the ozone elevation aloft can be attributed to the downward transport of air flow from higher altitudes. Furthermore, ozone accumulation in the winter could be influenced by the horizontal transport of air masses for the northern part of China. This study successfully used hexacopter UAV platforms to perform vertical observations within the boundary layer. This provides systematic classification of winter ozone distribution within the boundary layer.

Highlights

In many regions around the world, especially in developed cities, air pollution has been a major concern of the government, the public, and researchers
Using hexacopter unmanned aerial vehicle (UAV) monitoring platforms equipped with portable ozone monitors, 41 vertical ozone profiles were successfully obtained within the boundary layer
The UAV observations were reliable to capture the vertical variations of winter ozone within the boundary layer

Summary

Introduction

In many regions around the world, especially in developed cities, air pollution has been a major concern of the government, the public, and researchers. Ozone is one of the key air pollutants, which is generated by complex photochemical reactions among ozone precursors including carbon monoxide (CO), nitric oxide (NOx), and volatile organic compounds (VOCs). These are primarily emitted by anthropogenic activities [1,2,3,4,5,6]. Field observations are performed at ground level [7,8,9]. Ground-level distributions of air pollutants are firmly related to the atmospheric motions within the planetary boundary layer (PBL) such as vertical mixing and horizontal transport. The spatial resolution of surface measurements is not sufficient to fully understand the formation, accumulation, and dispersion mechanism of air pollutants

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Conclusion