High resolution vertical distributions of NO3 and N2O5 through the nocturnal boundary layer
The shallow mixing depth and vertical stratification of the lowest\nlevels of the atmosphere at night has implications for the chemistry\nof nitrogen oxides emitted from the surface. Here we report vertical\nprofiles of NO3, N2O5 and O3 measured from in-situ instruments on\na movable carriage on a 300 m tower. The study offers high-resolution\n(<1 m) vertical distributions of both NO3 and N2O5 and shows that\nthe nocturnal mixing ratios of these compounds vary widely over short\nvertical distance scales (10 m or less). Furthermore, there are systematic\ndifferences in the steady state lifetimes of NO3 and N2O5 and in\nthe partitioning among nitrogen oxides between different near-surface\nlayers. These differences imply that NO3 and N2O5 occupy distinct\nchemical regimes as a function of altitude, potentially serving as\nsinks for nitrogen oxides and O3 near the surface but as reservoirs\nof NOx and O3 aloft.