Correlation of nearshore ice movement with seabed ice gouges near Barrow, Alaska

Abstract

Nearshore patterns of ice motion near Barrow, Alaska, were monitored between 1973 and 1979 with a sea ice radar system. Side scan sonar surveys of the seafloor were made at the same location during the summers of 1977 and 1978. The two data sets provide information on ice motion, ice gouging, and the rate and character of seabed deformation by ice. Four ice stages (open water, freeze‐up, winter, and breakup) can be defined on the basis of the frequency and patterns of ice motion and ice cover processes as recorded by the radar system. In all four ice stages the dominant ice motion was nearly parallel to the coast. Side scan sonar surveys show that the principal ice gouge directions nearshore were at a high angle to the coast and to the predominant direction of ice drift in both years. Gouge density was greatest in a narrow zone centered about the 10‐m isobath which reflects the distribution of deep ice keels and the pattern of reworking of the seafloor by waves and currents. We believe the majority of observed gouges were formed by keels of multiyear ice floes during an event that occurred in July 1975, 2 years before the first seabed survey. Persistence of the gouge pattern from 1975 until 1977 is attributed to persistence of the ice cover and limited reworking by waves and currents, or additional gouging. The observed decrease in gouge density between 1977 and 1978 is attributed to (1) seafloor reworking and gouge infilling by storms and (2) the absence of ice conditions that were conducive to creating fresh gouges.