High resolution vertical distributions of NOsub3/sub and Nsub2/subOsub5/sub through the nocturnal boundary layer

摘要

The shallow mixing depth and vertical stratification of the lowest levels ofthe atmosphere at night has implications for the chemistry of nitrogenoxides emitted from the surface. Here we report vertical profiles ofNO₃, N₂O₅ and O₃ measured from in-situ instruments on a movablecarriage on a 300 m tower. The study offers high-resolution (<1 m)vertical distributions of both NO₃ and N₂O₅ and shows thatthe nocturnal mixing ratios of these compounds vary widely over shortvertical distance scales (10 m or less). Furthermore, there are systematicdifferences in the steady state lifetimes of NO₃ and N₂O₅ andin the partitioning among nitrogen oxides between different near-surfacelayers. These differences imply that NO₃ and N₂O₅ occupydistinct chemical regimes as a function of altitude, potentially serving assinks for nitrogen oxides and O₃ near the surface but as reservoirs ofNO_x and O₃ aloft.