Ice watch

  
 


Ice watch photographs looking towards port, starboard, and straight down.
 
In transit visual ice observations revolved about the Ice Watch, which reported ice conditions every two hours. The ASPECT protocol was used to estimate ice thicknesses, classes and concentrations of the primary, secondary, and tertiary categories as well as pond fractions, and sediment covered ice. Measurements also included position, wind speed, air temperature, and ship speed. Photographs were taken from the starboard and port sides and one looking down at the breaking ice. Once a day at noon local time, panoramic photographs of the ice cover were were taken from the flying bridge of the Healy. These data provide a broad spatial overview of the physical properties exhibited by the ice cover. In addition to the ice watch atmosphere and ocean measurements were routinely recorded by ship instrumentation providing a series of snapshots across the top of the world.
 
Ice watch observations of ice concentration, pond fraction and thickness are plotted in the figure to the right. At the beginning of the cruise the ice was primarily first year ice. This was followed by a region of alternating bands of first year and multiyear ice. Above 79 N ice concentrations typically ranged from 0.8 to 1.0. However, there was a major exception from 8 to 11 September. There was a large area of polynyas and thin young ice extending from 88 25 N to 89 29 N. In this region open water and nilas accounted for 50 to 100% of the ice cover.

 Pond fractions were large early in the cruise, reaching peak values of 0.5 and averaging 0.25. The average thickness of undeformed ice is plotted in the bottom panel of the figure. There was a general trend of increasing ice thickness going northward, with fluctuations of +/- 0.5 m common. Thickness dropped significantly in the area from 88 to 89 N, where there was considerable open water and thin young ice.
Ice watch observations of ice type, ice concentration, pond fraction, and ice thickness during the 2005 trans-Arctic cruise. Observations were made every two hours.

Photos of nilas on 10 September and thick, multiyear ice on 24 September.