The potential impacts of climate change and future anthropogenic emissions on ozone levels in the USA are examined by linking global climate models to regional meteorological and air quality models during 3-year summer periods over the nine climate regions of the continental United States for three cases: (1) using 2016 meteorology and emissions (CTRL), (2) using 2050 meteorology and 2016 emissions (CASE1), and (3) using 2050 meteorology and 2050 emissions (CASE2). As climate change alone is expected to worsen ozone pollution and emission reductions are expected to reduce ozone concentrations, in this paper, the non-linear response of future ozone levels to both meteorological conditions and emissions was studied. The results show the well-known positive ozone correlation with surface temperature and negative ozone correlation with humidity in all regions. Climate change alone will increase future MDA8 ozone in the USA by 3.6 ppb. With climate change and policy intervention based on RCP 8.5, ozone levels will decrease 7.2 ppb on average for all climate regions in the USA. Furthermore, while climate change alone will double the number of stations violating the current National Ambient Air Quality Standard (NAAQS) for ozone in 2050, when policies are in effect, this number was reduced to 21 stations. The number of high-ozone days will also increase in climate change only case in all regions with an average of 5.7 extra high-ozone days which confirms previous studies. The results show that even with high-ozone precursor reductions, the ozone levels will still violate the current national ozone standard. Therefore, in order to meet the current ozone standard by 2050, more stringent climate and air pollution control policies for most regions in the USA are needed.

中文翻译：

---

排放和气候变化对美国未来臭氧浓度的影响

通过将全球气候模型与美国大陆九个气候区 3 年夏季期间的区域气象和空气质量模型联系起来，研究了气候变化和未来人为排放对美国臭氧水平的潜在影响，分为三种情况： (1) 使用 2016 年气象和排放 (CTRL)，(2) 使用 2050 气象和 2016 排放 (CASE1)，以及 (3) 使用 2050 气象和 2050 排放 (CASE2)。由于气候变化预计会加剧臭氧污染，而减排预计会降低臭氧浓度，因此本文研究了未来臭氧水平对气象条件和排放的非线性响应。结果表明，众所周知，所有地区的臭氧与地表温度呈正相关，臭氧与湿度呈负相关。仅气候变化就会使美国未来的 MDA8 臭氧增加 3.6 ppb。随着气候变化和基于 RCP 8.5 的政策干预，美国所有气候区的臭氧水平将平均下降 7.2 ppb。此外，尽管到 2050 年，仅气候变化就会使违反现行臭氧国家环境空气质量标准 (NAAQS) 的站点数量增加一倍，但当政策生效时，这一数字将减少到 21 个站点。仅在所有地区的气候变化情况下，高臭氧天数也将增加，平均 5.7 天，这证实了先前的研究。结果表明，即使臭氧前体减少量高，臭氧水平仍将违反现行的国家臭氧标准。因此，为了在 2050 年之前达到目前的臭氧标准，美国大部分地区需要更严格的气候和空气污染控制政策。