New International Collaborations for Atmospheric Ozone Research

对流层臭氧是一种重要的大气污染物，对人体健康、农作物和植被都有危害。它是大气氧化剂的主要前体，引发排放到大气中的大多数活性气体的降解，并且本身就是一种重要的温室气体。由于这种在大气化学和空气污染方面的核心作用，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，是在氮氧化物和阳光的存在下，由大气中挥发性有机化合物的复杂氧化形成的，而臭氧水平受原位化学过程、沉积和运输的综合影响。所有这些因素的不确定性影响了用于预测当前和未来臭氧水平的数值模式的准确性，从而阻碍了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决定了它是一种跨界污染物，需要国际合作，以便科学理解和制定有效的臭氧污染减缓政策。通过持续的NERC资助，我们开发了一种直接测量当地化学臭氧产生率的新方法-这种能力避免了排放清单和化学机制固有的限制，并明确区分了控制当地臭氧产生的化学因素和动力因素。在这个IOF项目中，我们将与来自里尔杜埃矿业公司（Mines Douai, Lille）的研究人员开展新的合作，这是欧洲唯一一个具有直接臭氧生成速率测量能力的研究小组，以支持交流专业知识，从而对两种仪器进行正式的相互比较，以确定影响测量的任何“未知未知”，并允许对测量准确性和精度进行独立评估。然后，我们将与美国的主要研究人员联系，对不同小组的多种臭氧产生率测量仪器的应用进行新颖的概念验证演示。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的臭氧产生是如何变化的（不同的树木种群具有不同的挥发性有机化合物排放曲线，这反过来影响臭氧化学）。我们将在密歇根大学生物站使用两个地点，一个反映了该地区的当代（主要是落叶）白杨林地，另一个是干预加速了森林演替，向更大的针叶林种群发展（反映了该地区森林种群的预期演变）。在所有其他因素（如本底空气成分、气象学）不变的情况下，在这两个地点同时进行平行的臭氧生成速率测量，可以直接确定森林树木数量变化所预期的臭氧化学变化。这一概念（结合同时直接测量臭氧产生）在其他情况下也有应用的范围，例如调查排放源（如主要城市）顺风处臭氧化学的演变，或者在英国的情况下，当受污染的欧洲气团平流到不列颠群岛时，臭氧产生的变化——如2003年光化学烟雾事件，预计未来发生的频率会更高。这个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产生速率测量能力的研究人员之间建立一个网络，以促进在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.