Variability of sea‐ice draft off Hokkaido in the Sea of Okhotsk revealed by a moored ice‐profiling sonar in winter of 1999

Using a moored ice‐profiling sonar along with an ADCP, a spatial section of draft across 855 km of sea ice was obtained for the first time in the southwestern part of the Okhotsk Sea near Hokkaido in winter of 1999. The draft evolved from 0.20 m in mid‐February to 1.45 m in late March with the overall value of 0.72 m. The draft characteristics were quite different between February and March before and after the period of strong winds. The increase of the mean draft from February to March was associated with the increase of deformed ice. The maximum draft observed was ∼17 m. Ice volume was dominated by the contribution from portions of deformed ice especially in March. These results suggest that deformed ice dominated in the region of observation and dynamical processes were mainly responsible for the evolution of draft.