Cloud Occurrence at Arctic Atmospheric Observatories Matthew Shupe

Cloud Occurrence at Arctic Atmospheric Observatories Matthew Shupe, Taneil Uttal, Daniel Wolfe, David Welsh Special Thanks for Ny’Alesund MPL Data: Masataka Shiobara, James Campbell AMS Polar Meteorology and Oceanography 2007

Arctic Cloud Stations Barrow SHEBA Tiksi Radar Lidar Eureka Alert Ny’Alesund Summit An Example Station

Observatories Site Instruments Dates SHEBA, Arctic Ocean Radar, lidar, ceilometer 1997 -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

Data Processing Considerations • Use a combination of cloud radar and lidar, depending on station • “Cloud fraction” is from the perspective of verticallypointing, surface-based instruments • All but SHEBA must be considered preliminary in nature, more detailed multi-instrument analyses will follow

Total Cloud Fraction Radar Lidar Surface observations • Very cloudy in general at all stations (~75% total) • Summer/Fall maximum?

Vertical Distribution Radar Lidar Bimodal Dist’n in Vertical Lots of Low-level Clouds

Annual and Vertical Distribution

Cloud Type Classification • 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.

Annual Cycles of Cloud Type • Mixed-phase clouds: Maxima in transition seasons. • Similar trends and magnitudes between SHEBA and Barrow

Occurrence of Cloud Liquid is present throughout the year more than half of the time!

Vertical Distributions of Cloud Type • Remarkable similarities • Slightly different balance at surface.

Annual & Vertical Dist’n of Type

Conclusions • High annual fraction: ~75% • Remarkable similarities in vertical. • Similar dist’n of phase for W. Arctic sites. • Liquid is frequent (and important!) Future Work • Radar-lidar combination at all sites. • Classification work at all sites using new algorithm. • More detailed analysis of boundaries Thank You.