Search

• Maximum daily 8-h (MDA8) O 3 rose by ∼20.7% in June 2015–2019 over North China Plain. • The MDA8 O 3 increase induced by aerosols reduction was limited (∼2.9%). • The MDA8 O 3 increased by ∼9.7% due to the precursor emissions changes. • The meteorological fluctuation led to an increase of ∼6.4% in MDA8 O 3. Continuous aggravated surface O 3 over North China Plain (NCP) has attracted widely public concern. Herein, we evaluated the effects of changes in aerosols, precursor emissions, and meteorology on O 3 in summer (June) of 2015–2019 over NCP via 8 scenarios with WRF-Chem model. The simulated mean MDA8 O 3 in urban areas of 13 major cities in NCP increased by 17.1%∼34.8%, which matched well with the observations (10.8%∼33.1%). Meanwhile, the model could faithfully reproduce the changes in aerosol loads, precursors, and meteorological conditions. A relatively-even O 3 increase (+1.2%∼+3.9% for 24-h O 3 and +1.0%∼+3.8% for MDA8 O 3) was induced by PM 2.5 dropping, which was consistent with the geographic distribution of regional PM 2.5 reduction. Meanwhile, the NO 2 reduction coupled with a near-constant VOCs led to the elevated VOCs/NO x ratios, and then caused O 3 rising in the areas under VOCs-limited regimes. Therein, the pronounced increases occurred in Handan, Xingtai, Shijiazhuang, Tangshan, and Langfang (+10.7%∼+13.6% for 24-h O 3 and +10.2%∼+12.2% for MDA8 O 3); while the increases in other cities were 5.7%∼10.5% for 24-h O 3 and 4.9%∼9.2% for MDA8 O 3. Besides, the meteorological fluctuations brought about the more noticeable O 3 increases in northern parts (+12.5%∼+13.5% for 24-h O 3 and +11.2%∼+12.4% for MDA8 O 3) than those in southern and central parts (+3.2%∼+9.3% for 24-h O 3 and +3.7%∼+8.8% for MDA8 O 3). The sum of the impacts of the three drivers reached 16.7%∼21.9%, which were comparable to the changes of the observed O 3. Therefore, exploring reasonable emissions-reduction strategies is essential for the ozone pollution mitigation over this region. [Display omitted] [ABSTRACT FROM AUTHOR]