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.