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

Abstract

This study evaluated interannual variation in the subsurface aragonite undersaturation zone (omega Ar<1 layer) in the Pacific Arctic Ocean, using data from the 2016-2019 period. The upper boundary (DEP omega<1UB ) of the omega Ar<1 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 omega<1 UB , but the direction of its effect was opposite west and east of -166 degrees W. The lower boundary (DEP omega<1 LB ) of the omega Ar<1 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 omega<1LB , thus the thickness of the omega Ar<1 layer decreased.