A shifting lifetime for NOx Nitrogen oxides (NOx) have a central role in controlling air quality, so designing effective strategies to combat air pollution, especially by ozone and particulate matter, depends on knowing their atmospheric abundances. Those abundances depend not only on NOx production rates but also on their lifetimes. Laughner and Cohen report that NOx lifetimes can be measured directly from satellite observations of nitrogen dioxide. They used data on 49 North American cities to show how NOx lifetimes there changed between 2005 and 2014. Accounting for this change in lifetime should help to reconcile conflicting trends between bottom-up and top-down emissions estimates. Science, this issue p. 723 The lifetimes of atmospheric nitrogen oxides can be determined by remote satellite measurements. NOx lifetime relates nonlinearly to its own concentration; therefore, by observing how NOx lifetime changes with changes in its concentration, inferences can be made about the dominant chemistry occurring in an urban plume. We used satellite observations of NO2 from a new high-resolution product to show that NOx lifetime in approximately 30 North American cities has changed between 2005 and 2014 in a manner consistent with our understanding of NOx chemistry.

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直接观察北美城市氮氧化物寿命的变化

NOx 寿命的变化 氮氧化物 (NOx) 在控制空气质量方面起着核心作用，因此设计有效的策略来对抗空气污染，尤其是臭氧和颗粒物，取决于了解它们的大气丰度。这些丰度不仅取决于氮氧化物的产生率，还取决于它们的寿命。Laughner 和 Cohen 报告说，可以通过卫星对二氧化氮的观测直接测量 NOx 的寿命。他们使用了 49 个北美城市的数据来展示 2005 年至 2014 年期间那里的氮氧化物寿命如何变化。考虑到寿命中的这种变化应该有助于调和自下而上和自上而下排放估算之间的冲突趋势。科学，这个问题 p。723 大气中氮氧化物的寿命可以通过远程卫星测量来确定。NOx 寿命与其自身浓度呈非线性关系；因此，通过观察 NOx 寿命如何随着其浓度的变化而变化，可以推断出城市烟羽中发生的主要化学物质。我们使用来自一种新的高分辨率产品的 NO2 卫星观测结果表明，大约 30 个北美城市的 NOx 寿命在 2005 年至 2014 年之间发生了变化，其变化方式与我们对 NOx 化学的理解一致。