Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 7 2 2007 10.5194/acpd-7-4597-2007 http://www.atmos-chem-phys-discuss.net/7/4597/2007/ http://www.atmos-chem-phys-discuss.net/7/4597/2007/acpd-7-4597-2007.html http://www.atmos-chem-phys-discuss.net/7/4597/2007/acpd-7-4597-2007.pdf 4597 4656 2007-04-02 First space-borne measurements of the altitude distribution of mesospheric magnesium species M. Scharringhausen scharr@iup.physik.uni-bremen.de A. C. Aikin J. P. Burrows M. Sinnhuber Institute of Environmental Physics, University of Bremen, Bremen, Germany Institute for Astrophysics and Computational Sciences, The Catholic University of America, Washington, D.C., USA We present a joint retrieval as well as first results for mesospheric air density and mesospheric Magnesium species (Mg and Mg+) using limb data from the SCIAMACHY instrument on board the European ENVISAT satellite. Metallic species like neutral Mg, ionized Mg+ and others (Fe, Si, Li, etc.) ablate from meteoric dust, enter the gas phase and occur at high altitudes (≥70 km). Emissions from these species are clearly observed in the SCIAMACHY limb measurements. These emissions are used to retrieve total and thermospheric column densities as well as altitude-resolved profiles of metallic species in the altitude range of 70–92 km. In this paper, neutral Magnesium as well as its ionized counterpart Mg+ is considered. These species feature resonance fluorescence in the wavelength range 279 and 285 nm and thus have a rather simple excitation process. A radiative transfer model (RTM) for the mesosphere has been developed and validated. Based on a ray tracing kernel, radiances in a large wavelength range from 240–300 nm covering limb as well as nadir geometry can be calculated. 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