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Abstract Among the various environmental factors that affect isoprene emissions, drought has only been given limited attention. Four different drought response (DR) schemes were implemented in the Model of Emissions of Gases and Aerosols from Nature (MEGAN, version 2.1), and the Community Multiscale Air Quality (CMAQ) model was applied to investigate the drought impacts on air quality during both drought and normal years in China. Generally, all DR schemes decrease isoprene emissions except for mild drought conditions. The significant decrease and even termination of isoprene emissions are predicted in South China under severe drought conditions. During the drought period, the DR scheme considering both mild and severe drought (SMD) improves the model performance especially in severe drought‐hit regions when compared with the Ozone Monitoring Instrument (OMI) averaged formaldehyde vertical column density (HCHO VCD). The results show that most of the DR schemes decrease simulated ozone (O3) and secondary organic aerosols (SOA) levels. For both O3and SOA, noticeable changes are predicted in the Sichuan Basin (5 ppb and 4 µg m−3for O3and SOA, respectively). This investigation is the first modeling study to investigate the impacts of isoprene drought response on air quality in China.
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Changes in the Relative Importance of Biogenic Isoprene and Soil NOx Emissions on Ozone Concentrations in Nonattainment Areas of the United States
Abstract Reductions in anthropogenic emissions have drawn increasing attention to the role of the biosphere in O3production chemistry in U.S. cities. We report the results of chemical transport model sensitivity simulations exploring the relative impacts of biogenic isoprene and soil nitrogen oxides (NOx) emissions on O3and its temporal variability. We compare scenarios with high and low anthropogenic NOx emissions representing the reductions that have occurred in recent decades. As expected, summertime O3concentrations become less sensitive to perturbations in biogenic isoprene emissions as anthropogenic NOx emissions decline. However, we demonstrate for the first time that across policy relevant O3nonattainment areas of the United States, O3becomes more sensitive to perturbations in soil NOx emissions than to identical perturbations in isoprene emissions. We show that interannual variability in soil NOx emissions may now have larger impacts on interannual O3variability than isoprene emissions in many areas where the latter would have dominated in the recent past.
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- Award ID(s):
- 1750328
- PAR ID:
- 10369930
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 127
- Issue:
- 13
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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