How fast is landfast sea ice? A study of the attachment and detachment of nearshore ice at Barrow, Alaska

During the two winters between 2003 and 2005, a land-based marine radar observed the nearshore ice motion during the development and decay of landfast ice near Barrow, Alaska. The radar imagery captured individual events at high temporal resolution, revealing deformation processes and allowing calculation of ice velocity and acceleration. Atmospheric forcing during these events appeared to be irrelevant since no corollary was found in local meteorological observations. Detailed examination of the radar imagery showed that backscatter from sea ice targets oscillated in signal strength (flickered) prior to detachment, as previously observed by (Shapiro, L.H. (1987), Mechanical Properties of Sea Ice Deformation in the near Shore Zone, in OCSEAP Final Reports, V.72, pp. 357-584,U.S. Dept. of Commerce, NOAA). Determination of ice acceleration after detachment allowed estimation of water drag beneath the ice.