Cloud Occurrence at Arctic Atmospheric Observatories
Matthew Shupe, Taneil Uttal, Daniel Wolfe, David Welsh
AMS Polar Meteorology and Oceanography 2007
Special Thanks for Ny’Alesund MPL Data:Masataka Shiobara, James Campbell
Arctic Cloud StationsBarrow
SHEBA
Eureka
Alert
Ny’Alesund
Tiksi
Radar Lidar
An Example Station
Summit
Site Instruments DatesSHEBA, Arctic Ocean Radar, lidar,
ceilometer1997-1998
Barrow, USA Radar, lidar, ceilometer
1998 – Present
Ny’Alesund, Norway Lidar 2002 – Present
Eureka, Canada Radar, lidar 2005 – Present
Alert, Canada Ceilometer ?
Tiksi, Russia None yet Not yet
Summit, Greenland None yet Not yet
Observatories
Data Processing Considerations
• Use a combination of cloud radar and lidar, depending on station
• “Cloud fraction” is from the perspective of vertically-pointing, surface-based instruments
• All but SHEBA must be considered preliminary in nature, more detailed multi-instrument analyses will follow
• Very cloudy in general at all stations (~75% total)• Summer/Fall maximum?
Total Cloud Fraction
Radar
Lidar
Surface observations
Vertical Distribution
Bimodal Dist’n in Vertical
Lots of Low-level Clouds
Radar
Lidar
Annual and Vertical Distribution
• Instruments: radar, lidar, microwave radiometer, radiosonde.
• Manually classified. Automated system has been developed but not yet applied to all observations at all sites.
• 1 year of data at SHEBA and 7 years at Barrow.
Cloud Type Classification
Annual Cycles of Cloud Type
• Mixed-phase clouds: Maxima in transition seasons.• Similar trends and magnitudes between SHEBA and Barrow
Liquid is present throughout the year more than half of the time!
Occurrence of Cloud Liquid
• Remarkable similarities• Slightly different balance at surface.
Vertical Distributions of Cloud Type
Annual & Vertical Dist’n of Type
• High annual fraction: ~75%• Remarkable similarities in vertical.• Similar dist’n of phase for W. Arctic sites. • Liquid is frequent (and important!)
• Radar-lidar combination at all sites.• Classification work at all sites using new algorithm.• More detailed analysis of boundaries
Conclusions
Future Work
Thank You.