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Abstract As the abyssal oceans warm, stratification is also expected to change in response. This change may impact mixing and vertical transport by altering the buoyancy flux, internal wave generation, and turbulent dissipation. In this study, repeated surveys of three hydrographic sections in the Southwest Pacific Basin between the 1990s and 2010s are used to estimate the change in buoyancy frequency. We find that below the°C isotherm,is on average reduced by a scaling factor of, a 12% reduction, per decade that intensifies with depth. At°C, we observe the biggest change:, or a 29% reduction per decade. Within the same period, the magnitude of vertical diffusive heat flux is also reduced by about, although this estimate is sensitive to the choice of estimated diffusivity. Finally, implications of these results for the heat budget and global ocean circulation are qualitatively discussed.
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Serendipitous Internal Wave Signals in Deep Argo Data
Abstract Serendipitous measurements of deep internal wave signatures are evident in oscillatory variations around the background descent rates reported by one model of Deep Argo float. For the 10,045 profiles analyzed here, the average root‐mean‐square of vertical velocity variances,, from 1,000 m to the seafloor, is 0.0045 m s−1, with a 5%–95% range of 0.0028–0.0067 m s−1. Dominant vertical wavelengths,λz, estimated from the integrals of lagged autocorrelation sequences have an average value of 757 m, with a 5%–95% range of 493–1,108 m. Bothandλzexhibit regional variations among and within some deep ocean basins, with generally largerand shorterλzin regions of rougher bathymetry or stronger deep currents. These correlations are both expected, since largerand shorterλzshould be found near internal wave generation regions.
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- Award ID(s):
- 1923558
- PAR ID:
- 10381073
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 7
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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