Nocturnal Ozone Enhancement Induced by Sea-Land Breezes During Summertime in Northern Coastal City Qingdao, China
This study investigated the influence of sea–land breezes on nocturnal spatial and temporal distribution of ozone (O<sub>3</sub>) and its potential effects on particulate nitrate formation in Qingdao, a coastal city in northern China. Observation campaigns were conducted to measure surfa...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Atmosphere |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4433/15/11/1350 |
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| Summary: | This study investigated the influence of sea–land breezes on nocturnal spatial and temporal distribution of ozone (O<sub>3</sub>) and its potential effects on particulate nitrate formation in Qingdao, a coastal city in northern China. Observation campaigns were conducted to measure surface air pollutants and meteorological factors during a typical sea–land breezes event from 22 to 23 July 2022. A coherent Doppler lidar (CDL) system was employed to continuously detect three-dimensional wind fields. The results revealed that nocturnal ozone levels were enhanced by a conversion of sea–land breezes. Initially, the prevailing northerly land breeze transported high concentrations of O<sub>3</sub> and other air pollutants from downtown to the Yellow Sea. As the sea breeze developed in the afternoon, the sea breeze front advanced northward, resulting in a flow of high O<sub>3</sub> concentrations back into inland areas. This penetration of the sea breeze front led to a notable spike in O<sub>3</sub> concentrations between 16:00 on 22 July and 02:00 on 23 July across downtown areas, with an average increase of over 70 μg/m<sup>3</sup> within 10 min. Notably, a time lag in peak O<sub>3</sub> concentration was observed with southern downtown areas peaking before northern rural areas. During this period, combined pollution of O<sub>3</sub> and PM<sub>2.5</sub> was also observed. These findings indicated that the nighttime increase in O<sub>3</sub> concentrations, coupled with enhanced atmospheric oxidation, would likely promote the secondary conversion of gaseous precursors into PM<sub>2.5</sub>. |
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| ISSN: | 2073-4433 |