TITLE:      Observations of Sea Ice Properties in the Marguerite Bay Region
            during Spring (talk) given at the 
	    Third U.S. Southern Ocean Globec Science Investigator Meeting
AUTHORS:    Bruce Elder, Sharon Stammerjohn, Keran Claffey, Donald Perovich,
            and Raymond Smith
DATE:       10-12 December 2001
PLACE:      Arlington, VA
Posted WEB: http://www.ccpo.odu.edu/Research/globec/3sciinvest/dperovich.htm

POSTED: http://www.ccpo.odu.edu/Research/globec/3sciinvest/perovich_files/v3_document.htm
POSTED: *.ppt


ABSTRACT

During the spring 2001 cruise of the SO GLOBEC experiment, we sampled ice
physical and optical properties in the Marguerite Bay area of the Palmer
Peninsula. At 12 sites, ice thickness was measured every meter along
10- to 120-m-long survey lines. The combined mean ice thickness for these
surveys was 62 cm, with a median of 43 cm and a maximum thickness of 280 cm.
Snow depths ranged from 1 cm to 57 cm, averaging 16 cm. At 45% of the thickness
holes, a combination of deep snow and thin ice resulted in negative freeboard. 
A stratigraphic analysis of ice thin sections showed that more than half of
the ice cover was granular and that virtually all of the upper 20 cm of the 
ice was granular. There are indications that snow-ice formation at the surface
contributed significantly to ice formation. At most sites the base of the snow 
cover was wet and saline. The average ice salinity was 7 psu, with the largest
salinities, of approximately 10 psu, found near the surface. Ice temperatures 
were warm resulting in large brine volumes. The thicker ice showed evidence of
extensive rafting and ridging. Visible albedos were in the 0.9-0.95 range for
snow-covered ice and 0.5-0.6 range for bare ice. Maximum transmittances were
between 400 and 500 nm. For 30-cm thick ice with 7 cm of snow, peak
transmittances were only 2 to 3%. Removing the snowcover increased
transmittance by an order of magnitude to almost 30%.