Abstract：
The planetary boundary layer (PBL) characteristics during ozone (O3) episodes in China have been extensively studied; however, knowledge of the impact of boundary layer jets (BLJs) on O3 vertical distribution is limited. This study conducted a field campaign from 1 to 8 December 2020 to examine the vertical structure of the O3 concentration and wind velocity within the boundary layer at two sites (Foshan: FS, Maoming: MM) in Guangdong. Utilising lidar observations and the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), distinct spatial distribution patterns of O3 over FS and MM influenced by BLJs were identified. The BLJs at both locations exhibited pronounced diurnal variations with a nocturnal maximum exceeding 11 m/s at a height of approximately 500 m. The nocturnal enhancement of BLJs resulted from inertial oscillations coupled with diurnal thermal forcing over sloping terrain. A stronger BLJ at FS induced an evident uplift of O3 and the prevailing northeasterly wind facilitated the transport of O3 in the nocturnal residual layer from FS to MM. After sunrise, surface heating and the development of the PBL caused the air mass with elevated O3 levels in the residual layer to descend to ground level. At MM, calm surface winds, a weaker BLJ at 500 m height, and strong downdrafts collectively contributed to a significant increase in surface O3 concentration in subsequent days. These findings contribute to our understanding of the interactions between BLJs and variations in surface air pollutant concentrations, thereby providing important insights for future regional emissions control measures.
摘要：
在中国已经广泛研究了臭氧（O3）事件期间的行星边界层（PBL）特征；但是，边界层射流（BLJ）对O3垂直分布的影响的知识是有限的。这项研究于2020年12月1日至8日进行了一次野外运动，以检查两个地点边界层内O3浓度和风速的垂直结构（佛山：FS，茂名：MM）在广东。利用激光雷达观测以及与化学（WRF-Chem）耦合的天气研究和预报模型，确定了受BLJ影响的O3在FS和MM上的不同空间分布模式。两个位置的BLJ表现出明显的昼夜变化，在大约500m的高度上，夜间最大值超过11m/s。BLJ的夜间增强是由于惯性振荡以及倾斜地形上的昼夜热强迫所致。FS处较强的BLJ引起O3的明显隆起，盛行的东北风促进了夜间残留层中O3从FS到MM的运输。日出后,表面加热和PBL的发展导致残留层中O3含量升高的空气质量下降到地面。在MM，平静的地面风，500米高度处较弱的BLJ，强烈的下降气流共同导致了随后几天表面O3浓度的显着增加。这些发现有助于我们理解BLJ与地面空气污染物浓度变化之间的相互作用，从而为未来的区域排放控制措施提供重要的见解。
