Early Freeze-Up over the Bering Sea Controlled by the Aleutian Low

Abstract

Early freeze-up affects the local marine environment and ecosystem throughout the entire Bering Sea. However, the process governing early freeze-up, which is responsible for the most significant interannual variation in the December sea ice area (SIA), is not well understood. Here, we show that the SIA in December is modulated by the Aleutian low in November by altering poleward heat transport (PHT). The stronger the November PHT is, the lower the December SIA. The rise in heat transport across the Bering Strait in November is consistent with the decrease in SIA in December, with a correlation of −0.71, further validating the regulatory role of PHT. The Aleutian low anomaly controls the local wind field, further altering the sea surface temperature and PHT. The center of the anomalous low-pressure in the east (west) generates the northerly (southeasterly) anomaly over the northern Bering Sea, leading to acceleration (suppression) of seawater cooling and weakening (enhancement) of the PHT. It is also found that a strong northerly surface current has a greater influence on the later SIA than warm water temperature. Hence, atmospheric forcing causing changes in ocean forcing is imperative to understand early freeze-up.