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Abyssal Stratification Change in the Southwest Pacific Basin
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  • Helen Jingyi Zhang,
  • Caitlin Whalen,
  • Nirnimesh Kumar,
  • Sarah G. Purkey
Helen Jingyi Zhang
University of Washington Applied Physics Laboratory

Corresponding Author:hjzhang@uw.edu

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Caitlin Whalen
University of Washington
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Nirnimesh Kumar
University of Washington
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Sarah G. Purkey
Scripps Institution of Oceanography, UCSD
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As abyssal ocean properties are altered by climate change, density stratification may be expected to change in response. This shift can affect the buoyancy flux, internal wave generation, and turbulent dissipation, which may impact mixing and vertical transport. In this study, repeated surveys of three hydrographic sections in the Southwest Pacific Basin between the 1990s-2010s are used to estimate the change in buoyancy frequency N. We find that below Θ = 0.8◦C, N is reduced by a mean scaling factor of 0.88{plus minus}0.06 per decade. This reduction is intensified at depth, with the biggest change observed at Θ=0.63◦C by a scaling factor of 0.71{plus minus}0.07. Within the same time period, the magnitude of per unit area vertical diffusive heat flux is reduced by about 0.01 Wm, although this estimate is sensitive to the choice of estimated diffusivity. Finally, implications on heat budget and global ocean circulation are qualitatively discussed.