Field work close to Svea


During a few days in March 2003 ice growth in a small lead (8*10 m) was observed during calm wind consitions. The lead was created as a part of an experiment conducted by the Arctic Technology group at the University Studies at Svalbard (UNIS). The initial ice cover was a uniform layer of 1.1 m thick congelation ice.

 
The lead was made by drilling and cutting through the ice using a sea ice drills and chain saws. Initial attempts to pull each block of 1m^3 up by a tractor showed to be inefficient, and a grab had to join in to get the lead opened up in one day. All small ice blocks and most of the slush was removed from the lead about 18:30 in the evening, and it took only 30 minutes before a 10 cm layer of slush had formed in the -25 degrees C cold air. 

 
 
The next day the ice cover was still 10 cm thick, but now a solid layer of new ice had formed, with beatiful ice roses glittering in the sun.



 

A horisontal thin section from the original 1.1 m thick ice cover vieved through polarized glass. The light that passes through are spread like in a prism an make ice crystals of the same orientation appear with the same color.


 

A horisontal thin section from the new 10 cm thick ice cover vieved through polarized glass. The crystals are much smaller than to the left and reveal that this ice did originally consist of loose seperate crystals, called frazil ice, in a slushy ice layer.


 

A vertical thin section of the 1.1 m thick original ice cover. The long vertical crystals are easily distinguished, and tell us that one crystals grows slowly downwards as heat is conducted upwards through the ice above.



 

A vertical thin section of the 10 cm ice cover formed during the night. The upper 4 cm is the congealed frazil ice that has a caotic orientation of small crystals in all directions, and the lower part is congelation ice with the longer elongated crystals.