Abstract

Abstract. The distribution of meteorological elements has always been an important factor in determining the horizontal and vertical distribution of particles in the atmosphere. To study the effect of meteorological elements on the three-dimensional distribution structure of particles, mobile vehicle lidar and fixed-location observations were collected in the western Guangdong–Hong Kong–Macao Greater Bay Area of China during September and October in 2019 and 2020. Vertical aerosol extinction coefficient, depolarization ratio, and wind and temperature profiles were measured using a micro pulse lidar, a Raman scattering lidar, and a Doppler wind profile lidar installed on a mobile monitoring vehicle. The mechanism of how wind and temperature in the boundary layer affects the horizontal and vertical distribution of particles was analysed. The results show that particles were mostly distributed in downstream areas on days with moderate wind speed in the boundary layer, whereas they were distributed homogeneously on days with weaker wind. There are three typical types of vertical distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area (GBA): surface single layer, elevated single layer, and double layer. Analysis of wind profiles and Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) backward trajectory reveals different sources of particles for the three types. Particles concentrating near the temperature inversion and multiple inversions could cause more than one peak in the extinction coefficient profile. There were two mechanisms affecting the distribution of particulate matter in the upper and lower boundary layers. Based on this observational study, a general model of meteorological elements affecting the vertical distribution of urban particulate matter is proposed.

Highlights

  • The Guangdong–Hong Kong–Macao Greater Bay Area (GBA) is one of China’s national key economic development regions

  • The horizontal distribution of particles was obtained by conducting mobile vehicle lidar observations in the GBA

  • The reason for choosing this route is that it covers the major urban agglomerations in the western part of the Guangdong– Hong Kong–Macao Greater Bay Area, which contains a large number of anthropogenic aerosol emission sources

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Summary

Introduction

The Guangdong–Hong Kong–Macao Greater Bay Area (GBA) is one of China’s national key economic development regions. Lidar is an active remote sensing device It emits a laser light beam and receives a backscatter signal, which can be further used to retrieve the vertical distribution of particle optical properties, wind, and temperature. It has been widely applied in the fields of meteorology and environmental science. In the past few years, several vehicle-based observational experiments have been carried out (Lv et al, 2017, 2020; Lyu et al, 2018; Zhao et al, 2021; Fan et al, 2018), but research aimed at multi-lidar observations and the effect of the vertical structure of meteorological factors on the distribution of particles has largely been an underexplored domain, especially in the GBA. The authors were motivated to perform observations in the western GBA with a multi-lidar system installed on a vehicle to study the influence of the three-dimensional structure of meteorological elements on the distribution of particles

Description of observations
Multi-lidar system
Calculation of extinction coefficient and depolarization ratio
HYSPLIT backward trajectory model
Mobile vehicle lidar observations
Fixed-location lidar observations
Type I: surface single layer
Type II: elevated single layer
Type III: double layer
Extinction coefficient at different wind speeds
Conclusions
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