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Abstract Hundreds of full-depth temperature and salinity profiles collected by Deepglider autonomous underwater vehicles (AUVs) in the North Atlantic reveal robust signals in eddy isopycnal vertical displacement and horizontal current throughout the entire water column. In separate glider missions southeast of Bermuda, subsurface-intensified cold, fresh coherent vortices were observed with velocities exceeding 20 cm s −1 at depths greater than 1000 m. With vertical resolution on the order of 20 m or less, these full-depth glider slant profiles newly permit estimation of scaled vertical wavenumber spectra from the barotropic through the 40th baroclinic mode. Geostrophic turbulence theory predictions of spectral slopes associated with the forward enstrophy cascade and proportional to inverse wavenumber cubed generally agree with glider-derived quasi-universal spectra of potential and kinetic energy found at a variety of locations distinguished by a wide range of mean surface eddy kinetic energy. Water-column average spectral estimates merge at high vertical mode number to established descriptions of internal wave spectra. Among glider mission sites, geographic and seasonal variability implicate bottom drag as a mechanism for dissipation, but also the need for more persistent sampling of the deep ocean. Significance Statement Relative to upper-ocean measurements of temperature, salinity, and velocity, deep ocean measurements (below 2000 m) are fewer in number and more difficult to collect. Deep measurements are needed, however, to explore the nature of deep ocean circulation contributing to the global redistribution of heat and to determine how upper-ocean behavior impacts or drives deep motions. Understanding of geographic and temporal variability in vertical structures of currents and eddies enables improved description of energy pathways in the ocean driven by turbulent interactions. In this study, we use newly developed autonomous underwater vehicles, capable of diving to the seafloor and back on a near daily basis, to collect high-resolution full ocean depth measurements at various locations in the North Atlantic. These measurements reveal connections between surface and deep motions, and importantly show their time evolution. Results of analyzing these vertical structures reveal the deep ocean to regularly “feel” events in the upper ocean and permit new comparisons to deep motions in climate models.
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AUTONOMOUS, FIXED-FOCUS, HIGH-RESOLUTION DEEP-SEA CAMERA SYSTEMS
The development and design of versatile, autonomous, fixed-focused deep-sea cameras capable of operation to depths of 6,000 m and 11,000 m, that have been deployed on numerous research submersibles and deep-sea platforms since 2016, is presented. The optical assembly of the cameras consists of two lens elements and a high pressure-corrected dome port, optimized to correct for image distortion, produce minimal vignetting, and yield a depth of field which extends from ~0.5 m to infinity within the subsea environment. Three configurations of deep-sea housing are integrated with these optics, such that the internal chassis designs permit GoPro HERO4™ and HERO11™ camera modules to be axially aligned with the corrector and dome optics. The GoPro cameras are fitted with a 5.4 mm non-distortion lens and 1TB microSD memory cards; and are connected to a high-capacity USB-C battery or custom Li-battery pack to provide selfcontained power. The supplemental power and recording media storage permit operations for >24 hours for 27MP still imaging at a high (~5 second) repetition rate, or ~18 hours for 4K or 5.3K cinematic video acquisition at 30 fps. The self-contained power and autonomous design of these cameras allow a wide range of installation options for deep-sea vehicles, towed systems, and seafloor sampling devices to document oceanographic processes. In addition to their use for highresolution documentation of Earth-ocean phenomena and life, they have been used in numerous outreach efforts to educate and engage students and the public about the importance of continued exploration and study of “inner space” – the global ocean and seafloor.
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- Award ID(s):
- 2313521
- PAR ID:
- 10580491
- Publisher / Repository:
- Journal of Ocean Technology
- Date Published:
- Journal Name:
- Journal of ocean technology
- Volume:
- 19
- Issue:
- 3
- ISSN:
- 0099-4529
- Page Range / eLocation ID:
- 64-99
- Subject(s) / Keyword(s):
- Deep-sea cameras Fixed-focus Deep-submergence research Versatility in subsea imaging systems Subsea depth of field
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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