Characteristics of the Arctic environment in the southern Beaufort Sea from Ice Exercise data

Abstract

In early March of 2016 and 2018, the Naval Postgraduate School participated in the biennial naval Ice Exercise (ICEX) conducted in the southern Beaufort Sea. Oceanographic and acoustic data sets collected near the ice camps during both events are compared. While the drift track of the ice camp during ICEX-18 was approximately one-degree south of the track in ICEX-16, there are important similarities in the oceanographic structure shown in both datasets. These characteristics have significant impacts on sound propagation in the region and may affect the performance of acoustic systems such as naval sonar and UUV navigation. Of particular interest are properties at the interface between the cold, fresh surface layer and the contrasting warm, saline Pacific Summer Water (PSW) that lays immediately below it. Sensors indicate turbulent mixing of high-spice and low-spice water occurs at this interface. PSW also sets up a stable subsurface sound channel with Pacific Winter Water and Atlantic Water layers below it. Strength of the sound channel varies from year to year; however, historical data from this region indicates an increasing trend. Other oceanographic features found in the upper 200 m of the under-ice water column in our 120-kHz echosounder dataset are discussed.