What is the pycnocline in the Arctic Ocean?

In the Arctic Ocean, the pycnocline is a strong density gradient that separates a thin, less dense surface layer from the main body of water, which maintains a relatively uniform density.1

Because Arctic water temperatures are consistently cold, variations in density are primarily determined by changes in salinity. This pycnocline acts as a physical barrier that restricts convective motion and the vertical transfer of heat and salt, effectively allowing the surface layer to function as a cap over the deeper, warmer water masses below. While pycnoclines are generally defined as boundaries where density increases rapidly with depth, the specific structure in the Arctic is a key feature of its two-layer system.12