Retrieval of stratospheric NO2 vertical profiles from ground-based measurements at Vanscoy, Saskatchewan

One of the active trace gases that influences the ozone distribution is nitrogen dioxide (NO₂). Since the role of NO₂ in the photochemistry of ozone is strongly dependent on altitude, it is important to know not only the NO₂ total amount, but also its vertical distribution. In this paper, we use the approach proposed by K. E. Preston et al. (1997) to retrieve NO₂ altitude profiles from slant column measurements. The observations were made with a portable UV-visible spectrometer operated on the ground during the Middle Atmospheric Nitrogen TRend Assessment (MANTRA) balloon campaign carried out at Vanscoy, Saskatchewan, Canada (52° N, 107° W), from 18 to 25 August 1998. The NO₂ profile retrieved from the ground-based observations is compared with the co-located and simultaneous NO₂ profile measured by a balloon-borne UV-visible spectrometer during sunrise on August 24. Finally, the retrieved profiles are compared with the output of the MEZON 3D stratospheric chemical transport model and the results are discussed.