NOCTURNAL VERTICAL-DISTRIBUTION OF STRATOSPHERIC O-3, NO2 AND NO3 FROM BALLOON MEASUREMENTS

Simultaneous measurements of NO2, O-3, NO3, and aerosol extinction coe fficient vertical distribution have been made in the middle of the nig ht by the AMON (Absorption par Minoritaires Ozone et No-x) instrument on October 16, 1993, from a balloon platform at float altitude, above Aire sur l'Adour in the south of France. Amen measures atmospheric tra nsmission in the UV Visible range, using the star occultation method. Vertical distributions, obtained between 20 and 40 km, are calculated by a tangent ray inversion technique. Measurements of NO and NO2 by th e HALOE (HALogen Occultation Experiment) instrument aboard UARS were a lso available on October 17, 1993, close to Aire sur l'Adour. Comparis on with box model simulations, including heterogeneous reactions, show s that while an increase of NO3 concentration at 38 km could be explai ned by an occasionally steep vertical gradient of temperature concentr ations, another increase of both NO2 and NO3 measured by AMON between 22 to 25 km, i.e. in the upper part of the aerosol layer, cannot be ex plained by the model. Such an increase is also present on one HALOE pr ofile close to Aire sur l'Adour, for the same altitude range.