Gravitational separation suggested by O₂/N₂, δ¹⁵N of N₂, δ¹⁸O of O₂, Ar/N₂ observed in the lowermost part of the stratosphere at northern middle and high latitudes in the early spring of 2002

Lower stratospheric O₂/N₂ ratios (δ(O₂/N₂)) at northern middle and high latitudes were measured by analyzing aircraft air samples collected between Nagoya, Japan and Svalbard Islands in the Arctic during the early spring of 2002. The measured values of δ(O₂/N₂) are relatively uniform horizontally in the lowermost part of the stratosphere but increase with height. Vertical distributions of δ(O₂/N₂) and the CO₂ concentration observed over Svalbard Islands and Barrow, Alaska are negatively correlated. By examining the rates of change in δ(O₂/N₂) and δ¹³C of CO₂ relative to the CO₂ concentration, such a correlation observed is mainly attributable to upward propagation of their seasonal cycles produced on the ground surface for the troposphere and height-dependent air age for the stratosphere. However, from the vertical profiles of δ¹⁵N of N₂, δ ¹⁸O of O₂ and δ(Ar/N₂) measured in the lowermost part of the stratosphere over Svalbard Islands, it is suggested that the relationship between δ(O₂/N₂) and the CO₂ concentration is affected by the gravitational separation. By correcting the measured δ(O₂/N₂) and δ ¹³C values for this gravitational separation, the relationships of δ(O₂/N₂) and δ ¹³C with the CO₂ concentration are consistent with those expected from their secular trends in the troposphere.