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Atmospheric background - mesosphere |
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Although the formation of nanoparticles of meteoric composition in the Earth's upper atmosphere has long been theorised [Rosinski and
Snow, 1961], no definitive identification of these species has been made to date either through optical detection or sampling at
characteristic altitudes (> 60 km).
Meteoric smoke has been implicated in a number of important atmospheric processes such as the nucleation of noctilucent clouds (NLCs) [Rapp and Thomas, 2006], the condensation of stratospheric sulphate aerosols [Murphy et al., 1998], the production of nitric acid (HNO3) from nitrogen pentoxide (N2O5) in the upper stratosphere [Stiller et al., 2005] and the conversion of H2SO4 to SO2 in the upper stratosphere [Mills et al., 2005]. However, relatively little progress has been made in establishing the details of the nucleation processes and chemical compositions of the initial smoke particles (< 5 nm diameter) from which larger particles subsequently evolve or in consideration of particle shape and structure, which is likely to be somewhat different to the idealised spherical, compact form assumed in 1-D modelling studies to date, e.g. Hunten et al. (1980). As part of the Mesospheric Aerosol-Genesis, Interaction and Composition (MAGIC) project (http://www.misu.su.se/magic.html) to unravel some of the mysteries of meteoric smoke particles, we have carried out a series of laboratory studies to generate and analyse likely analogue species from iron and silicon precursors (Fe and Si/SiO are thought to be the predominant species released into the upper atmosphere from the ablation of transient meteors; Plane, 2003) - see laboratory and modelling sections. |
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References Hunten, D.M., et al. (1980). Smoke and dust particles of meteoric origin in the mesosphere and stratosphere. J. Atmos. Sci. 37, 1342. Murphy, D.M., et al. (1998). In situ measurements of organics, meteoritic material, mercury and other elements in aerosols at 5 to 19 kilometres. Science, 282, 1664. Rapp, M., and G.E. Thomas (2006). Modeling the microphysics of mesospheric ice particles: Assessment of current capabilities and basic sensitivities. J. Atmos. Solar-Terr. Phys. 68, 715. Mills M.J., et al. (2005). Mesospheric sulfate aerosol layer. J. Geophys. Res. 110, doi:10.1029/2005JD006242. Plane, J.M.C. (2003). Atmospheric chemistry of meteoric metals. Chem. Rev. 103, 4963. Rosinski, J., and R.H. Snow (1961). Secondary particulate matter from meteor vapours. J. Meteor. 18, 736. Stiller, G.P., et al. (2005). An enhanced HNO3 second maximum in the Antarctic midwinter upper stratosphere 2003. J. Geophys. Res. 110, 10.1029/2005JD006011. Mills M.J., et al. (2005). Mesospheric sulfate aerosol layer. J. Geophys. Res. 110, doi:10.1029/2005JD006242. |
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For information related to this project Go to > Modelling work > Laboratory work |
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