Matthew Shupe

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Cloud Occurrence and Phase at Arctic Atmospheric
Observatories Further progress towards
understanding Arctic clouds
Matthew Shupe Von Walden Ed Eloranta Taneil
Uttal James Campbell Masataka Shiobara Sandy
Starkweather
AMS Polar Met. Ocean. 2009 Madison, WI
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Observatories
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Site Instruments Dates
Atqasuk, AK, USA Ceilometer 1999 Present
Barrow, AK, USA Radar, lidar, mwr, ceilometer, soundings 1998 Present
NyAlesund, Norway Lidar 2002 Present
Eureka, Canada Radar, lidar, mwr, soundings 2005 Present
SHEBA, Arctic Ocean Radar, lidar, mwr, ceilometer, soundings 1997-1998
Summit, Greenland Ceilometer 2001-2002
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Methods and Details

• What is a Cloud? It depends on your
  perspective and objective
• Clouds identified using thresholds for each
  sensor that aim to distinguish cloudy from clear
  sky signals.
• Different sensors at each site impact the
  results
• Phase classification requires radar, lidar, mwr,
  and radiosonde (only available at 3 sites)

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Cloud Occurrence Fraction
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Variability in time and space
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Cloud Phase Type Fraction
Barrow
SHEBA
Eureka
All (black) Ice (blue) Mixed-Phase
(orange) Liquid (red) Liquid present (red dash)
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Vertical Distribution
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Diurnal Cycle
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Cloud Occurrence Fraction
Cloud Fraction Anomaly

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Cloud Persistence
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Phase vs. Temperature
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To Conclude

• Detailed perspective from the surface
  complements satellite climatologies and in situ
  campaigns.
• Results are appropriate for model evaluation and
  comparisons with satellite retrievals.
• Need more observations to better establish
  baselines and to detect change.
• Needs E. Arctic, over the sea-ice, longer
  records.
• Much of data used in this analysis is available
  at CADIS archive (www.eol.ucar.edu/projects/aon-ca
  dis)