New International Collaborations for Atmospheric Ozone Research

对流层臭氧是一种重要的空气污染物，对人类健康、农作物和植被有害。它是大气氧化剂的主要前体，可引发排放到大气中的大多数活性气体的降解，并且其本身就是一种重要的温室气体。由于对流层臭氧在大气化学和空气污染中的核心作用，了解、预测和管理对流层臭氧水平的能力是大气科学研究的一个关键目标。这一目标很难实现，因为臭氧是一种二次污染物，是由挥发性有机化合物在氮氧化物和阳光存在下复杂氧化而在大气中形成的，并且原位化学过程、沉积和运输的结合控制着臭氧水平。所有这些因素的不确定性都会影响用于预测当前和未来臭氧水平的数值模型的准确性，从而阻碍制定减轻臭氧暴露的最佳空气质量政策。臭氧化学的时间尺度导致它成为一种跨界污染物，需要国际合作以进行科学理解和制定有效的臭氧污染缓解政策。通过 NERC 的持续资助，我们开发了一种直接测量当地化学臭氧生产率的新方法 - 这种能力避免了排放清单和化学机制固有的限制，并且明确区分了控制当地臭氧生产的化学因素和动态因素。在这个 IOF 项目中，我们将与来自里尔杜埃矿业公司（欧洲唯一具有直接臭氧生产率测量能力的其他组织）的研究人员开展新的合作，以支持专业知识交流，从而对两种仪器进行正式的相互比较，以便识别对测量产生不同影响的任何“未知的未知因素”，并允许对测量精度和精密度进行独立评估。然后，我们将与美国领先的研究人员联系，对多种臭氧生产率测量的应用进行新颖的概念验证演示来自不同群体的乐器聚集在一起。在这个泵启动项目中，我们将应用这种方法来了解不同森林类型中臭氧产量的差异（不同的树群具有不同的挥发性有机化合物排放特征，进而影响臭氧化学）。我们将使用密歇根大学生物站的两个地点，一个地点反映了该地区当代（主要是落叶的）白杨林地，另一个地点的干预措施加速了森林向更大针叶树种群的演替（反映了该地区森林种群的预期演变）。通过在这两个地点同时进行平行的臭氧生产率测量，在所有其他因素（例如背景空气成分、气象）不变的情况下，可以直接确定因林木种群变化而预期的臭氧化学变化。这一概念（结合同步直接臭氧产生测量）在其他场景中具有应用范围，例如调查排放源（例如大城市）下风处臭氧化学的演变，或者在英国，随着受污染的欧洲气团平流到不列颠群岛上空，臭氧产生发生变化 - 例如 2003 年光化学烟雾事件，预计未来会更频繁地发生。该泵启动项目的最后一个组成部分是在国际上具有直接臭氧生产率测量能力的研究人员之间建立一个网络，以促进未来应用这一概念的合作。

Tropospheric ozone is an important air pollutant, harmful to human health, agricultural crops and vegetation. It is the main precursor to the atmospheric oxidants which initiate the degradation of most reactive gases emitted to the atmosphere, and is an important greenhouse gas in its own right. As a consequence of this central role in atmospheric chemistry and air pollution, the capacity to understand, predict and manage tropospheric ozone levels is a key goal for atmospheric science research. This goal is hard to achieve, as ozone is a secondary pollutant, formed in the atmosphere from the complex oxidation of VOCs in the presence of NOx and sunlight, and a combination of in situ chemical processes, deposition and transport govern ozone levels. Uncertainties in all of these factors affect the accuracy of numerical models used to predict current and future ozone levels, and so hinder development of optimal air quality policies to mitigate ozone exposure. The timescale of ozone chemistry leads to it being a transboundary pollutant, requiring international collaboration for both scientific understanding and the development of effective ozone pollution mitigation policies.Through ongoing NERC funding, we have developed a novel approach for the direct measurement of local chemical ozone production rates - a capability which avoids limitations inherent in emissions inventories and chemical mechanisms, and which explicitly distinguishes between the chemical and dynamical factors controlling local ozone production. Within this IOF project, we will develop a new collaboration with researchers from Mines Douai, Lille - the only other group in Europe with direct ozone production rate measurement capability - in support of exchanging expertise, leading to a formal intercomparison of the two instruments, in order to identify any "unknown unknowns" affecting the measurements differently, and permit an independent evaluation of the measurement accuracy and precision.We will then link with leading researchers in the US to perform a novel proof-of-concept demonstration of the application of multiple ozone production rate measurement instruments from different groups together. Within this pump-priming project, we will apply this approach to understand how ozone production varies in different forest types (different tree populations have different emission profiles for volatile organic compounds, which in turn affect ozone chemistry). We will use two locations at the University of Michigan Biological Station, one which reflects the contemporary (primarily deciduous) aspen woodland of the region, and one in which interventions have accelerated the forest succession towards a larger coniferous population (reflecting the anticipated evolution of forest population in this area). By performing simultaneous parallel ozone production rate measurements in these two locations, with all other factors (e.g. background air composition, meteorology) constant, the change in ozone chemistry anticipated from shifting forest tree population may be directly ascertained. This concept (combined simultaneous direct ozone production measurements) has scope for application in other scenarios, for example investigating the evolution in ozone chemistry downwind of an emission source (such as a major city), or in a UK context the changing ozone production as polluted European airmasses are advected over the British Isles - events such as the 2003 photochemical smog episode, which are predicted to occur with greater frequency in the future. The final component of this pump-priming project is to initiate a network between researchers with direct ozone production rate measurement capability internationally, in order to facilitate collaborations to apply this concept in the future.