Search for OClO signatures from Odin limb radiance measurements using DOAS technique

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Particle Properties of Noctilucent Clouds as
Observed by the Odin Satellite
Bodil Karlsson, Jörg Gumbel, Markus Rapp, Jacek
Stegman
Department of Meteorology STOCKHOLM UNIVERSITY
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     BODIL KARLSSON ______________________________
____________________________________________      
    Particle Properties of Noctilucent Clouds as
Observed by the Odin Satellite         Thesis
for the degree of Filosofie Licentiat Stockholm,
March 2006
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www.misu.su.se/jacek
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• Outline
• - Why are we interested in NLCs?
• - NLC observations with Odin/OSIRIS
• Particle size retrievals
• Results, interpretation

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Altitude 81-83 km Latitude Poleward of
50o Season Summer
delicate interplay of microphysical processes
and large-scale transport that is not yet
completely understood.
are now regarded as an important test for our
understanding of middle atmospheric interactions
and climate change.
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Noctilucent clouds from space
OSIRIS spectra provide means for
detection NLC and characterisation NLC particles
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Northern hemisphere
Southern hemisphere
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NLC Occurrence Frequency NH/SH 2003/04 (Lpeak gt
7?109 ph cm-2 s-1 nm-1 str-1)
South North
gt75o
65-75o
55-65o
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Spectral Analysis, Particle Sizes
Mie curves from a monodisperse distribution of
spherical ice particles
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Albedo Contribution
? gt 310 nm
high albedo
low albedo
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Spectral Analysis, Particle Sizes
Mie curves from a monodisperse distribution
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How would we expect the particles to grow?
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Particle trajectories on top of the vertical wind
field and b) the particle growth for the same
trajectories.
Rapp et al. 2002
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Summary

• Noctilucent clouds are formed in the summer
  mesopause region at altitudes between 81 and 84
  km.
• Satellite measurements of scattered sunlight can
  been used to retrieve effective optical radii of
  the particles in NLC.
• Studies of the southern hemisphere summer
  mesosphere revealed that particles tend to grow
  slightly larger at the pole than at lower
  latitudes.
• The small increase in size appears to be
  determined by the available amount of water
  vapour rather than the temperature.
• NLC effective radius distributions show a
  bimodal structure right at the pole. This
  structure could be result of wave activity in the
  mesopause region.

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Future

• Comparisons with water measurements from SMR
• Comparisons with ENVISAT/scia-data
• Climatology
• Dynamical connections between the hemispheres
• Include longer wavelengths in the retrievals
  (Sasktran)

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The End
Thank you