Eddy covariance fluxes and vertical concentration gradient measurements of NO and NO 2 over a ponderosa pine ecosystem: observational evidence for within-canopy chemical removal of NO x

摘要: Abstract. Exchange of NOx (NO+NO2) between the atmosphere and biosphere is important for air quality, climate change, ecosystem nutrient dynamics. There are few direct ecosystem-scale measurements direction rate atmosphere–biosphere exchange NOx. As a result, complete description processes affecting following emission from soils and/or plants as they transit within plant/forest canopy to free remains poorly constrained debated. Here, we describe NO NO2 fluxes vertical concentration gradients made during Biosphere Effects on AeRosols Photochemistry EXperiment 2009. In general, daytime observe upward with counter-gradient NO. We find that forest smaller than calculated using observed flux–gradient relationships conserved tracers also measured soil emissions. interpret these differences primarily due chemistry converting higher nitrogen oxides canopy, which might be part mechanistic explanation "canopy reduction factor" applied emissions in large-scale models.