Matthew Shupe Von Walden Ed Eloranta Taneil UttalJames CampbellMasataka ShiobaraSandy Starkweather

Cloud Occurrence and Phase at Arctic Atmospheric Observatories:

Further progress towards understanding Arctic clouds

AMS Polar Met. & Ocean. 2009Madison, WI

Observatories

Site Instruments DatesAtqasuk, AK, USA Ceilometer 1999 – Present

Barrow, AK, USA Radar, lidar, mwr, ceilometer, soundings

1998 – Present

Ny’Alesund, 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

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)

Cloud Occurrence Fraction

Variability in time and space

Cloud “Phase” Type Fraction

All (black)Ice (blue)Mixed-Phase (orange)Liquid (red)Liquid present (red dash)

Barrow SHEBA Eureka

Vertical Distribution

Diurnal Cycle

AN

OM

AL

Y [

%]

Cloud Occurrence Fraction

C

loud

Fra

ctio

n A

nom

aly

[%]

Cloud “Persistence”

Phase vs. Temperature

• 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-cadis)

To Conclude