CEDAR Frontiers: Ice Clouds in the Mesosphere and their Variability By The AIM Science Team

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CEDAR Frontiers Ice Clouds in the Mesosphere and
their VariabilityBy The AIM Science Team

• Noctilucent clouds (NLC) were discovered over
  100 years ago.

• They are the Earths highest clouds (82 km) and
  comprise microscopic ice crystals (50nm radius)
  that form and grow in the vicinity of the
  high-latitude cold summer mesopause (T lt 130 K).
  
• Satellite measurements have established the
  existence of extensive clouds in the Arctic and
  Antarctic summer polar mesosphere (called PMC)
• Models of PMC formation show that
  super-saturated regions must be present for
  cloud nucleation. Yet, there are still no
  comprehensive knowledge of the chemical/thermal
  environment in which PMC form.

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• Variability
• Much heightened scientific and public interest in
  PMC/NLC due to their possible role as harbingers
  of climate change.
• Observations of increased brightness and
  frequency of occurrence.
• Recent unexpected observations at mid-latitudes
  in USA, Europe, and Asia.
• Possible association with rocket exhausts.
• New modeling results utilizing assimilated
  tropospheric forcing have extended the PMC field
  occasionally to mid-latitudes.
• Clear need to understand the geophysical drivers
  causing these temporary perturbations and whether
  they are associated with longer-term climate
  variability

Berger and Lübken, (2006)
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AIM Satellite

• AIM is the first satellite designed to
  investigate PMCs and will provide
  unprecedented advances in our understanding of
  their occurrence and variability.
• AIM will obtain novel simultaneous
  measurements of all the ingredients necessary
  to quantify PMC formation (temperature, water
  vapor, and other trace gasses and aerosols).
• Common volume (65-75) measurements will be
  made using sensitive solar occultation and UV
  panoramic imager.
• Excellent opportunities for ground-based
  coordinated measurements using existing radar,
  lidar, and passive optical instrumentation at
  key sites in the Arctic and Antarctic regions.
• Primary goal to build on AIMs capabilities.
• Possible coordinated campaigns at
• Poker Flat/HAARP, Resolute Bay, Sondrestrom,
  ALOMAR, SuperDarn, EISCAT (Scandinavia and
  Svalbard), and Davis and Rothera Stations,
  Antarctica.

Ground-based Observation in Coordination with AIM
AIM will observe four PMC seasons
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• PI J. Russell (Hampton University)
• Unprecedented advances in our understanding of
  NLCs
• - Solar Occultation (SOFIE) - Common
  volume measurement 65-75.
• - Panoramic UV nadir imaging (CIPS) -
  Two year mission (4 PMC seasons)
• - In-situ dust detection (CDE)
• - State-of-the-art modeling
• Ground-based coordinated studies will
  significantly enhance the scientific potential
  enabling new objectives to be addressed
• - Desired measurements include imaging, lidar
  and radar (PMSE) observations at mid- and high
  summer latitudes
• - AIM will provide lists of overpass information
  for selected sites with 2-week notice (with
  revised two-day prediction planned) via Internet
• - Coordination with IPY (2007-2008)
• We are currently compiling a list of sites and
  available instruments/measurements/modeling and
  capabilities and seek your valuable input to this
  important new program