In this work, we use observations and experimental emissions in a version of NOAA's National Air Quality Forecasting Capability to show that the COVID-19 economic slowdown led to disproportionate impacts on near-surface ozone concentrations across the contiguous U.S. (CONUS). The data-fusion methodology used here includes both U.S. EPA Air Quality System ground and the NASA Aura satellite Ozone Monitoring Instrument (OMI) NO₂ observations to infer the representative emissions changes due to the COVID-19 economic slowdown in the U.S. Results show that there were widespread decreases in anthropogenic (e.g., NO_x) emissions in the U.S. during March–June 2020, which led to widespread decreases in ozone concentrations in the rural regions that are NO_x-limited, but also some localized increases near urban centers that are VOC-limited. Later in June–September, there were smaller decreases, and potentially some relative increases in NO_x emissions for many areas of the U.S. (e.g., south-southeast) that led to more extensive increases in ozone concentrations that are partly in agreement with observations. The widespread NO_x emissions changes also alters the O₃ photochemical formation regimes, most notably the NO_x emissions decreases in March–April, which can enhance (mitigate) the NO_x-limited (VOC-limited) regimes in different regions of CONUS. The average of all AirNow hourly O₃ changes for 2020–2019 range from about +1 to −4 ppb during March–September, and are associated with predominantly urban monitoring sites that demonstrate considerable spatiotemporal variability for the 2020 ozone changes compared to the previous five years individually (2015–2019). The simulated maximum values of the average O₃ changes for March–September range from about +8 to −4 ppb (or +40 to −10%). Results of this work have implications for the use of widespread controls of anthropogenic emissions, particularly those from mobile sources, used to curb ozone pollution under the current meteorological and climate conditions in the U.S.

在这项工作中，我们使用 NOAA 国家空气质量预报能力版本中的观测结果和实验排放来表明，COVID-19 经济放缓对美国本土 (CONUS) 的近地表臭氧浓度造成了不成比例的影响。这里使用的数据融合方法包括美国 EPA 空气质量系统地面和 NASA Aura 卫星臭氧监测仪 (OMI) NO ₂观测数据，以推断由于美国 COVID-19 经济放缓而导致的代表性排放变化。 2020 年 3 月至 6 月期间，美国的人为（例如氮_氧化物）排放量普遍减少，导致氮_氧化物限制的农村地区臭氧浓度普遍下降，但也导致城市中心附近的臭氧浓度出现局部增加VOC 限制。 6 月晚些时候至 9 月，美国许多地区（例如东南部地区）的氮_氧化物排放量减少幅度较小，并且可能相对增加，导致臭氧浓度更广泛增加，这在一定程度上与观测结果相符。广泛的NO _x排放变化也改变了O ₃光化学形成机制，最显着的是3月至4月NO _x排放量减少，这可以增强（减轻）美国本土不同地区的NO _x限制（VOC 限制）机制。 3 月至 9 月期间，2020 年至 2019 年所有 AirNow 每小时 O ₃变化的平均值约为 +1 至 -4 ppb，并且与主要城市监测点相关，这些监测点表明，与前五年相比，2020 年臭氧变化存在相当大的时空变化单独年份（2015-2019）。 3 月至 9 月平均 O ₃变化的模拟最大值范围约为 +8 至 -4 ppb（或 +40 至 -10%）。这项工作的结果对广泛控制人为排放，特别是来自移动源的排放具有影响，用于在美国当前的气象和气候条件下遏制臭氧污染