695 / 2024-09-19 08:55:56

Revisiting the Hydrographic Changes in the Upper Beaufort Gyre During Its Relaxation

Beaufort Gyre,Potential Energy Anomaly,Mixed Layer

The stability of the upper ocean is crucial for the exchange of momentum, heat, and salt between the sea ice and subsurface warm water in the Beaufort Gyre (BG) region of the Arctic Ocean. Here, the shifting phases of BG during 2003-2023 are objectively defined from observations. We find that the potential energy anomaly in the upper BG was significantly decrease in recent years. Further, the mixed layer became saltier and deeper across all seasons. We also find that the mixed layer heat content increased across nearly all seasons, except during July to September. Analysis from the model suggests that the cause of this warming was not atmospheric heat fluxes from above, but rather subsurface heat entrains upward. Our results have an important implication for the sea ice melting and oceanic vertical mixing when the BG relaxes.