
Increasing ocean stratification over the past half-century
Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. Here, we quantify changes in ocean stratification down to depths of 2,000 m using the squared buoyancy frequency N2 and newly available ocean temperature/salinity observations. We find that stratification globally has increased by a substantial 5.3% [5.0%, 5.8%] in recent decades (1960–2018) (the confidence interval is 5–95%); a rate of 0.90% per decade. Most of the increase (~71%) occurred in the upper 200 m of the ocean and resulted largely (>90%) from temperature changes, although salinity changes play an important role locally.
This is the accepted manuscript version of an article published in Nature Climate Change. It is subject to the SpringerNature Accepted Manuscript Terms of Use: https://www.springernature.com/gp/open-research/policies/accepted-manuscript-terms
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Work Title | Increasing ocean stratification over the past half-century |
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License | In Copyright (Rights Reserved) |
Work Type | Article |
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Publication Date | September 28, 2020 |
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Deposited | November 19, 2021 |
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