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

Abstract

This study evaluated interannual variation in the subsurface aragonite undersaturation zone (ΩAr<1 layer) in the Pacific Arctic Ocean, using data from the 2016？2019 period. The upper boundary (DEP^UB_ΩAr<1) of the Ω layer ΩAr<1 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 DEP^UB_ΩAr<1, but the direction of its effect was opposite west and east of ~166 W. The lower boundary (DEP^LB_ΩAr<1) of the ΩAr<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 LB circulation pattern significantly lifted the DEP^LB_Ω<1, thus the thickness of the ΩAr<1 layer decreased.