A shipboard dataset of winter hydrographic profiles from the northern Bering and Chukchi Seas was collected by the USCGC Polar Star from December 2020 to February 2021, using expendable conductivity-temperature-depth (XCTD) casts. The data are used to analyzed the hydrographic characteristics in the northern Bering Sea and the Chukchi Sea in winter. It shows that much of the water column was well mixed within the study domain. The geographical features of extremely cold water in three regions stood out in the dataset: on the northern Chukchi shelf, in the south of the Bering Strait, and around the St. Lawrence Island. Comparing our observations to the reanalysis GLO12 fields shows close agreement, enables us to explain these features. The results show that the cold water arise from surface cooling and local ice growth when being transported. Using the GLO12 dataset we compare the distribution of the extremely cold water in the winter of 2020-21 to other years.

hydrography, winter, Chukchi Sea