Overview of the ACROSS Campaign near Paris in Summer 2022

<p>ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) is an integrative, innovative, multi-scale project within the &#8220;Make Our Planet Great Again&#8221; (MOPGA) initiative designed to advance understanding of the fate of the photochemical processing of urban and biogenic air mass mixtures in the Paris region. An ACROSS hypothesis is that the anthropogenic-biogenic air mass mixing leads to changes in the production of oxygenated volatile organic compounds (VOCs) whose properties alter their importance in incorporation into secondary organic aerosols (SOA) and their roles in production of ozone and other relevant secondary species. A likely important factor is NOx transport to suburban biogenic environments and the resulting modification of key chemical processes.</p> <p>The key highlight of ACROSS was an intensive, multi-platform measurement campaign that took place in the summer of 2022. The campaign included measurements from multi-instrumented ground sites located in the urban, rural, and semi-rural Paris region including a 40-meter tower and from the ground in the Rambouillet suburban forest southwest of Paris, and airborne regional observations following the urban plume downwind of Paris and areas within 150 km (coordinated with other projects in the framework of the PANAME initiative). As the analysis proceeds, the data collected from this campaign will provide a unique snapshot of the properties that are characteristic of combinations of urban and biogenic air masses around one of the largest European megacities. This new knowledge will contribute to advancement of our understanding at the process level and will lead to the ability to better represent such complex systems in numerical models, ultimately resulting in improved capability to predict the impacts on air quality, regional climate, and global climate change.</p> <p>This presentation consists of a summary of the campaign organization and measurements. Some preliminary findings from the analysis of the observations in the early stages are shown as a complement to other, more focused evaluations that are given at this meeting.</p>