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Vertical ozone characteristics in urban boundary layer in Beijing
Zhiqiang Ma1, Honghui Xu, Wei Meng
1Institute of Urban Meteorology, China Meteorological Administration, Beijing, 100089, People's Republic of China. mazhqsos@163.com
Environmental Monitoring and Assessment
|November 7, 2012
Summary
Summer ozone levels in Beijing were high, peaking at 161.7 ppbv. Nocturnal boundary layer (NBL) development and low-level jets significantly influenced these ozone peaks, with southerly winds transporting ozone-rich air.
Area of Science:
- Atmospheric Chemistry
- Meteorology
- Environmental Science
Background:
- Ozone pollution is a significant environmental concern in urban areas.
- Understanding vertical ozone distribution is crucial for air quality management.
Purpose of the Study:
- To investigate vertical ozone profiles and meteorological parameters in Beijing's boundary layer during summer.
- To analyze the causes of high ozone concentrations, particularly nocturnal secondary ozone maxima.
Main Methods:
- Tethered balloon soundings (77 total) to measure vertical ozone and meteorological data.
- Comparison of ozonesonde and TEI 49C surface ozone measurements.
- Utilizing continuous analyzers on a 325-m meteorological tower for vertical ozone distribution.
Main Results:
- Surface ozone concentrations reached a maximum of 161.7 ppbv.
- Low-level jets were identified as critical factors for nocturnal ozone peaks in the nocturnal boundary layer (NBL).
- NBL height ranged from 47 to 280 m; ozone exceeded China's standard above 600 m for over 12 hours due to southerly airflow.
Conclusions:
- Nocturnal boundary layer dynamics, especially low-level jets, significantly impact urban ozone levels.
- Ozone-rich air masses transported by southerly winds can exacerbate air quality issues in Beijing.
- Effective air quality strategies must consider vertical ozone transport and nocturnal boundary layer processes.
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