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

Area of Science:

• Oceanography
• Marine Chemistry
• Climate Science

Background:

• The aragonite undersaturation zone (Ω_Ar<1 layer) is critical for marine calcifiers.
• Understanding its variability is key to predicting ecosystem impacts.

Purpose of the Study:

• To evaluate interannual variations in the subsurface aragonite undersaturation zone in the Pacific Arctic Ocean from 2016-2019.
• To identify factors controlling the upper and lower boundaries of this zone.

Main Methods:

• Analysis of oceanographic data from 2016-2019.
• Determination of water mass contributions and origins.
• Tracking the depth of the aragonite undersaturation zone boundaries.

Main Results:

• The upper boundary (DEP_Ω<1^UB) was primarily influenced by the Beaufort Gyre's freshwater accumulation.
• The lower boundary (DEP_Ω<1^LB) was significantly affected by an Atlantic-origin water intrusion in 2017.
• This intrusion led to a decrease in the overall thickness of the Ω_Ar<1 layer.

Conclusions:

• Beaufort Gyre intensity and anomalous water intrusions are key drivers of aragonite undersaturation zone variability.
• Changes in the Ω_Ar<1 layer thickness have implications for Arctic marine ecosystems.
• Regional differences in the effect of the Beaufort Gyre were observed.