Factors affecting the subsurface aragonite undersaturation layer in the Pacific Arctic region.

This study evaluated interannual variation in the subsurface aragonite undersaturation zone (Ω layer) in the Pacific Arctic Ocean, using data from the 2016-2019 period. The upper boundary (DEP) of the Ω layer generally formed at a depth where the contribution of corrosive Pacific water was approximately 98 %. The intensity of the Beaufort Gyre associated with freshwater accumulation mainly determined interannual variation in DEP, but the direction of its effect was opposite west and east of ~166°W. The lower boundary (DEP) of the Ω layer was generally found at a depth range where equal contributions of Pacific and Atlantic water were expected. An Atlantic-origin cold saline water intrusion event in 2017 caused by an anomalous atmospheric circulation pattern significantly lifted the DEP, thus the thickness of the Ω layer decreased.