Observations of Ice-Ocean Eddy Streets in the Sea of Okhotsk off the Hokkaido Coast Using Radar Images

Abstract

This study examines the features of fairly regular ocean-wave motion in which some eddy streets or backward breaking waves are successfully visualized using sea ice floes as a tracer. These examinations are made using the time sequence of radar imagery data collected during the past 20 years, 1969?88; the correspondence of the radar images with the actual pattern is partially confirmed through aircraft observations. The ice-ocean eddy street or backward breaking wave pattern runs parallel to the coastline at a distance of about 20 km from the Hokkaido coast; the eddy street also corresponds to a boundary between the Soya Warm Current and colder, less saline offshore water. The wave motion is characterized by wavelengths of 40?55 km, phase velocities of 14?20 km day ?1 and periods of 2.3?3.5 days. The regular ice-ocean wave motion pattern was observed when pack ice had a small ice concentration composed of uniform sized ice floes and weak winds. The sea ice floes serve as a highly effective flow indicator in the radar observations of the ice-ocean wave motion.