Impacts of the 2020 COVID-19 Shutdown Measures on Ozone Production in the Los Angeles Basin

Ivey, Cesunica E.; Gao, Ziqi; Do, Khanh; Yeganeh, Arash Kashfi; Russell, Armistead G.; Blanchard, Charles L.; Lee, Sangmi

doi:10.26434/chemrxiv.12805367

Cited by 3 publications

(2 citation statements)

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“…The reduction in traffic volumes during the lockdown from March to May led to a decrease in observed CO and NO X . 3,16 As a result, we expected an overall reduction in ozone levels over the SoCAB region. The average diurnal ozone concentrations before the lockdown (Jan-Feb) in 2020 were noticeably greater than the average from 2016-2019 for all 15 building sites.…”

Section: Discussionmentioning

confidence: 91%

“…2 The COVID-19 shutdown also provided an estimation of the impacts of future large-scale emission reduction strategies on ozone concentrations in SoCAB. 3 Of particular interest is the exploration of possible differences in ozone prediction performance of different modeling approaches during periods of signicant emissions and meteorological anomalies. The Community Multiscale Air Quality (CMAQ) modeling system, developed by the U.S. Environmental Protection Agency (EPA), is widely-used for multi-day air quality simulations to estimate air pollutant concentrations with prescribed emissions and meteorology inputs (Ooka et al, 2011;Rao et al, 1996;Wong et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Performance of machine learning for ozone modeling in Southern California during the COVID-19 shutdown

Do,

Yeganeh,

Gao

et al. 2024

Environ. Sci.: Atmos.

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Section: Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Performance of machine learning for ozone modeling in Southern California during the COVID-19 shutdown

Do,

Yeganeh,

Gao

et al. 2024

Environ. Sci.: Atmos.

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Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

Laughner

Neu

Schimel

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to the atmosphere are reduced. Furthermore, the abrupt reduction in emissions during the lockdown periods led to clearly observable changes in atmospheric composition, which provide direct insight into feedbacks between the Earth system and human activity. While air pollutants and greenhouse gases share many common anthropogenic sources, there is a sharp difference in the response of their atmospheric concentrations to COVID-19 emissions changes, due in large part to their different lifetimes. Here, we discuss several key takeaways from modeling and observational studies. First, despite dramatic declines in mobility and associated vehicular emissions, the atmospheric growth rates of greenhouse gases were not slowed, in part due to decreased ocean uptake of CO2 and a likely increase in CH4 lifetime from reduced NOx emissions. Second, the response of O3 to decreased NOx emissions showed significant spatial and temporal variability, due to differing chemical regimes around the world. Finally, the overall response of atmospheric composition to emissions changes is heavily modulated by factors including carbon-cycle feedbacks to CH4 and CO2, background pollutant levels, the timing and location of emissions changes, and climate feedbacks on air quality, such as wildfires and the ozone climate penalty.

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Ozone Trends and the Ability of Models to Reproduce the 2020 Ozone Concentrations in the South Coast Air Basin in Southern California under the COVID-19 Restrictions

et al. 2022

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The current U.S. emission control requirements for on-road motor vehicles are driven by the ozone problem in the South Coast Air Basin (SoCAB) in southern California. Based on ozone modeling performed for Air Quality Management Plans (AQMPs), the SoCAB ozone attainment plan requires large (>80%) amounts of emission reductions in oxides of nitrogen (NOx) from current levels with more modest (~40%) controls on Volatile Organic Compounds (VOC). The shelter in place orders in response to the 2020 COVID-19 pandemic resulted in an immediate reduction in emissions, but instead of ozone being reduced, in 2020 the SoCAB saw some of the highest observed ozone levels in decades. We used the abrupt emissions reductions from 2019 to 2020 caused by COVID-19 to conduct a dynamic model evaluation of the Community Multiscale Air Quality (CMAQ) model to evaluate whether the models used to develop ozone control plans can correctly simulate the ozone response to the emissions reductions. Ozone modeling was conducted for three scenarios: 2019 Base, 2020 business-as-usual (i.e., without COVID reductions), and 2020 COVID. We found that modeled ozone changes between 2019 and 2020 were generally consistent with the observed ozone changes. We determined that meteorology played the major role in the increases in ozone between 2019 and 2020; however, the reduction in NOX emissions also caused ozone increases in Los Angeles County and into western San Bernardino County, with more widespread ozone decreases further to the east.

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Impacts of the 2020 COVID-19 Shutdown Measures on Ozone Production in the Los Angeles Basin

Cited by 3 publications

References 0 publications

Performance of machine learning for ozone modeling in Southern California during the COVID-19 shutdown

Performance of machine learning for ozone modeling in Southern California during the COVID-19 shutdown

Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

Ozone Trends and the Ability of Models to Reproduce the 2020 Ozone Concentrations in the South Coast Air Basin in Southern California under the COVID-19 Restrictions

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