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Publication Title

Atmospheric Environment: X






This study quantified the impact of non-controllable and urban emission sources on the enhancement of ozone (O3) in the troposphere. These enhancements were investigated using data from simultaneous ozonesonde launches at Half Moon Bay (HMB), CA and San Jose (SJ), CA on eleven dates in July and August 2018. The urban O3 enhancement in the SJ vertical profile was derived by subtracting out HMB, which represents baseline O3, from the urban SJ profile. Within the planetary boundary layer (PBL), urban emissions had a large impact on SJ, as SJ O3 was 20–30 ppb higher than HMB for all dates. Above the PBL, most enhancement profiles remained close to zero, indicating little differences aloft between HMB and SJ. The two sites had strong correlation coefficients (CCs), highlighting the influence of baseline O3 on SJ. A major axis regression for all vertical levels between SJ and HMB revealed a slope of 1.00 SJ ppb/HMB ppb and intercept of 0.004 ppb. The percent contribution of mixing layer (ML) O3 to tropospheric O3 and tropospheric O3 to total column O3 demonstrates the predominant influence of baseline O3 on the O3 profile, even over a polluted urban region. The contribution of ML O3 was low for all dates, between 2 and 6%, whereas the tropospheric contribution was 11–18%. These findings emphasize the importance of baseline O3 in regions with reduced vertical mixing; polluted urban air near the surface has minimal impacts on O3 concentrations above the PBL.

Funding Number


Funding Sponsor

National Aeronautics and Space Administration


Planetary boundary layer, Surface emission, Upper air ozone, Urban


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Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Meteorology and Climate Science