How are deep Arctic Ocean currents different from surface currents?

In the Arctic Ocean, surface and deep currents are distinguished by their driving forces, structure, and speed.

Surface Currents

Surface waters are primarily driven by wind and density differences. A defining feature is a large, clockwise gyre that dominates the Amerasia Basin. These surface waters are part of a two-layer system, separated from deeper water by a strong density gradient known as a pycnocline, which restricts vertical heat and salt transfer. Because of this, the surface layer acts as a cap over the deeper, warmer water masses.1

Deep Currents

Deep-ocean circulation is driven by thermohaline circulation—the movement of water caused by horizontal differences in temperature and salinity rather than wind. These currents are significantly more sluggish than surface currents, with speeds likely less than two inches per second. While surface circulation is well-observed through ice drift, deep-water movement is often inferred from the distribution of seawater properties like salinity, temperature, and dissolved oxygen.123