Advancing process understanding of ozone dry deposition across scales

Abstract

Chapter 2 European NO x emissions in WRF-Chem derived from OMI: impacts on summertime surface ozone Chapter 3 Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales Chapter 4 The combined impact of canopy stability and soil NO x exchange on ozone removal in a temperate deciduous forest Chapter 5 Simulating the effect of land surface heterogeneity on ozone dry deposition in a Large Eddy Simulation model 121 Chapter 6 General discussion and outlook 143 References 157 Acknowledgements 189 About the author 193 Since these two reactions combined do not result in production or loss of NO x and ozone under typical daytime circumstances, this is considered a chemical null-cycle called the photo-stationary state. Production of ozone follows a different pathway, which involves VOCs. Consider the following reaction chain for a generic hydrocarbon RH, consisting of a chain of carbon atoms bound to hydrogen atoms (Jacob, 1999): In contrast, the sources of NO x are primarily anthropogenic. NO x is a by-product of combustion reactions, and as such its dominant sources are road transport, energy generation and industry. Present-day global anthropogenic NO x emissions are estimated at ±37 Tg N yr −1 (Crippa et al., 2018). Besides anthropogenic sources, NO x has considerable 1.3 Observations 1.3.1 Surface concentration measurementsSurface concentration measurements are the most common type of ozone observations. These measurements are representative for surface ozone concentrations, which is important information from an air quality perspective. Additionally, the surface ozone concentration partly determines how much ozone is removed at the surface by dry deposition. Measurements can provide information about ozone air quality in cities, which is important for assessments of human exposure to air pollution. Since the photochemical ozone formation regime is often distinctly different in cities compared to remote regions, monitoring ozone in so-called rural background stations is important as well (Tarasick et al., 2019). These 1.4 Modelling the sources and sinks of boundary layer ozone 13 from several kilometers to hundreds of kilometers. In contrast, ozone deposition to forest canopies depends on forest properties such as canopy height, which is on the order of several tens of meters. Likewise, turbulent motions in the atmosphere happen on a timescale of several minutes, while the average lifetime of an ozone molecule in the troposphere is several weeks. Integrating these spatial and temporal scales in a single model is not possible given the current computational constraints. Therefore, we apply a range of different models that resolve the relevant processes at different spatial and temporal scales. The underlying principles of these models are introduced in this section. These models are in a so-called Eulerian form, meaning that the three-dimensional model domain is subdivided into fixed grid cells of a smaller size, through which air flows. Equation 1.5 is a so-ca...