Acoustic Scattering in Deep Ocean Waveguides due to Small Scale Ocean Structure

2007 ◽  
Author(s):  
Michael Wolfson
Keyword(s):  
Acoustic Scattering ◽  
Deep Ocean ◽  
Small Scale ◽  
Ocean Waveguides

Impacts of meso and submesoscale dynamics on the horizontal dispersion of sinking particles from the surface to the deep ocean

2020 ◽  
Author(s):  
Lu Wang ◽  
Jonathan Gula ◽  
Jeremy Collin ◽  
Laurent Memery
Keyword(s):  
General Structure ◽  
Finite Size ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Horizontal Distribution ◽  
Particle Dispersion ◽  
Small Scale ◽  
Transport Pathways ◽  
Horizontal Dispersion ◽  
Sinking Particles

<p>Energetic eddy fields generated by meso and submesoscale dynamics induce tridimensional particle transport pathways, which complicate the interpretation of observed Particulate Organic Carbon (POC) fluxes using sediment traps. It is therefore of importance to understand how horizontal dispersion of particles is structured by these dynamics from surface to depth. In this modelling study, we use a Lagrangian method to backtrack sinking particles collected at various depths ranging from 500 m to 4700 m at the PAP (Porcupine Abyssal Plain) site. Particle trajectories are computed using high-resolution simulations of the Regional Ocean Modelling System (ROMS). Our results show that the horizontal distribution of particles with sinking velocities below 100 m d<sup>-1</sup> presents a large small-scale heterogeneity. Mesoscale eddies act to define the general structure of particle patches while submesoscale features shape particle distributions through convergence/divergence processes. Distribution patterns of particles tracked from different depths suggest regime shifts of particle dispersion between subsurface layers. To identify and quantify these regimes, we perform 2d experiments at specific depths from 100 m to 4000 m and relate the Lagrangian statistics to the characteristics of the different dynamical regimes identified using vertical profiles of eddy energy and Finite Size Lyapunov Exponents (FSLE) approach.                                                                                                                                                               </p>

scholarly journals Emergence of Wind-Driven Near-Inertial Waves in the Deep Ocean Triggered by Small-Scale Eddy Vorticity Structures

2011 ◽  
Vol 41 (7) ◽  
pp. 1297-1307 ◽  
Author(s):  
Eric Danioux ◽  
Patrice Klein ◽  
Matthew W. Hecht ◽  
Nobumasa Komori ◽  
Guillaume Roullet ◽  
...  
Keyword(s):  
Mesoscale Eddy ◽  
Deep Ocean ◽  
Mean Amplitude ◽  
Relative Vorticity ◽  
Wind Forcing ◽  
Small Scale ◽  
Inertial Waves ◽  
Deep Interior ◽  
Eddy Field ◽  
Baroclinic Modes

Abstract Using numerical simulations forced by a uniform realistic wind time series, the authors show that the presence of a mesoscale eddy field at midlatitudes accelerates the vertical propagation of the wind-forced near-inertial waves (NIW) and produces the emergence of a maximum of vertical velocity into the deep ocean (around 2500 m) characterized by a mean amplitude of 25 m day−1, a dominant 2f frequency, and scales as small as O(30 km). These results differ from previous studies that reported a smaller depth and larger scales. The authors show that the larger depth observed in the present study (2500 m instead of 1700 m) is due to the wind forcing duration that allows the first five baroclinic modes to disperse and to impact the deep NIW maximum (instead of the first two modes as reported before). The smaller scales (30 km instead of 90 km) are explained by a resonance mechanism (described in previous studies) that affects the high NIW baroclinic modes, but only when small-scale relative vorticity structures (related to the mesoscale eddy field) have an amplitude that is large enough. These results, which point out the importance of the wind forcing duration and the resolution, indicate that the emergence of a deep NIW maximum with a 2f frequency reported before is a robust feature that is enhanced with more realistic conditions. Such 2f frequency in the deep interior raises the question of the mechanisms, still unresolved, that may ultimately transfer this superinertial energy into mixing at these depths.

scholarly journals Progress in understanding of Indian Ocean circulation, variability, air-sea exchange and impacts on biogeochemistry

2021 ◽  
Author(s):  
Helen E. Phillips ◽  
Amit Tandon ◽  
Ryo Furue ◽  
Raleigh Hood ◽  
Caroline Ummenhofer ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Climate Variability ◽  
Ocean Circulation ◽  
Large Scale ◽  
New Technologies ◽  
Heat Content ◽  
Deep Ocean ◽  
Small Scale ◽  
Circulation Patterns ◽  
The Indian Ocean

Abstract. Over the past decade, our understanding of the Indian Ocean has advanced through concerted efforts toward measuring the ocean circulation and its water properties, detecting changes in water masses, and linking physical processes to ecologically important variables. New circulation pathways and mechanisms have been discovered, which control atmospheric and oceanic mean state and variability. This review brings together new understanding of the ocean-atmosphere system in the Indian Ocean since the last comprehensive review, describing the Indian Ocean circulation patterns, air-sea interactions and climate variability. The second International Indian Ocean Expedition (IIOE-2) and related efforts have motivated the application of new technologies to deliver higher-resolution observations and models of Indian Ocean processes. As a result we are discovering the importance of small scale processes in setting the large-scale gradients and circulation, interactions between physical and biogeochemical processes, interactions between boundary currents and the interior, and between the surface and the deep ocean. In the last decade we have seen rapid warming of the Indian Ocean overlaid with extremes in the form of marine heatwaves. These events have motivated studies that have delivered new insight into the variability in ocean heat content and exchanges in the Indian Ocean, and climate variability on interannual to decadal timescales.This synthesis paper reviews the advances in these areas in the last decade.

scholarly journals Observations of Small-Scale Secondary Instabilities during the Shoaling of Internal Bores on a Deep-Ocean Slope

2016 ◽  
Vol 46 (1) ◽  
pp. 219-231 ◽  
Author(s):  
Frédéric Cyr ◽  
Hans van Haren
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Dissipation Rate ◽  
Deep Ocean ◽  
Temperature Sensors ◽  
Small Scale ◽  
Cooling Phase ◽  
Northeast Atlantic Ocean ◽  
Internal Bores ◽  
Secondary Instabilities

AbstractThe Rockall Bank area, located in the northeast Atlantic Ocean, is a region dominated by topographically trapped diurnal tides. These tides generate up- and downslope displacements that can be locally described as swashing motions on the bank. Using high spatial and time resolution of moored temperature sensors, the transition toward the upslope flow (cooling phase) is described as a rapid upslope-propagating bore, likely generated by breaking trapped internal waves. Buoyant anomalies are found during the bore propagation, likely resulting from small-scale instabilities. The imbalance between the rate of disappearance of available potential energy and the dissipation rate of turbulent kinetic energy suggests that these instabilities are growing (i.e., young) and have high mixing potential.

scholarly journals Ecosystem function and services provided by the deep sea

2014 ◽  
Vol 11 (14) ◽  
pp. 3941-3963 ◽  
Author(s):  
A. R. Thurber ◽  
A. K. Sweetman ◽  
B. E. Narayanaswamy ◽  
D. O. B. Jones ◽  
J. Ingels ◽  
...  
Keyword(s):  
Deep Sea ◽  
Deep Ocean ◽  
Life Forms ◽  
Small Scale ◽  
Nutrient Regeneration ◽  
Microbial Oxidation ◽  
Global Functioning ◽  
Oxidation Of Methane ◽  
Deep Ocean Water ◽  
The Impact

Abstract. The deep sea is often viewed as a vast, dark, remote, and inhospitable environment, yet the deep ocean and seafloor are crucial to our lives through the services that they provide. Our understanding of how the deep sea functions remains limited, but when treated synoptically, a diversity of supporting, provisioning, regulating and cultural services becomes apparent. The biological pump transports carbon from the atmosphere into deep-ocean water masses that are separated over prolonged periods, reducing the impact of anthropogenic carbon release. Microbial oxidation of methane keeps another potent greenhouse gas out of the atmosphere while trapping carbon in authigenic carbonates. Nutrient regeneration by all faunal size classes provides the elements necessary for fueling surface productivity and fisheries, and microbial processes detoxify a diversity of compounds. Each of these processes occur on a very small scale, yet considering the vast area over which they occur they become important for the global functioning of the ocean. The deep sea also provides a wealth of resources, including fish stocks, enormous bioprospecting potential, and elements and energy reserves that are currently being extracted and will be increasingly important in the near future. Society benefits from the intrigue and mystery, the strange life forms, and the great unknown that has acted as a muse for inspiration and imagination since near the beginning of civilization. While many functions occur on the scale of microns to meters and timescales up to years, the derived services that result are only useful after centuries of integrated activity. This vast dark habitat, which covers the majority of the globe, harbors processes that directly impact humans in a variety of ways; however, the same traits that differentiate it from terrestrial or shallow marine systems also result in a greater need for integrated spatial and temporal understanding as it experiences increased use by society. In this manuscript we aim to provide a foundation for informed conservation and management of the deep sea by summarizing the important role of the deep sea in society.

scholarly journals Tidal mixing processes amid small-scale, deep-ocean topography

2015 ◽  
Vol 42 (2) ◽  
pp. 484-491 ◽  
Author(s):  
Andrew C. Dale ◽  
Mark E. Inall
Keyword(s):  
Deep Ocean ◽  
Tidal Mixing ◽  
Small Scale ◽  
Mixing Processes ◽  
Ocean Topography

scholarly journals Progress in understanding of Indian Ocean circulation, variability, air–sea exchange, and impacts on biogeochemistry

Ocean Science ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. 1677-1751
Author(s):  
Helen E. Phillips ◽  
Amit Tandon ◽  
Ryo Furue ◽  
Raleigh Hood ◽  
Caroline C. Ummenhofer ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Large Scale ◽  
New Technologies ◽  
Critical Role ◽  
Heat Content ◽  
Deep Ocean ◽  
Anthropogenic Heat ◽  
Small Scale ◽  
The Indian Ocean

Abstract. Over the past decade, our understanding of the Indian Ocean has advanced through concerted efforts toward measuring the ocean circulation and air–sea exchanges, detecting changes in water masses, and linking physical processes to ecologically important variables. New circulation pathways and mechanisms have been discovered that control atmospheric and oceanic mean state and variability. This review brings together new understanding of the ocean–atmosphere system in the Indian Ocean since the last comprehensive review, describing the Indian Ocean circulation patterns, air–sea interactions, and climate variability. Coordinated international focus on the Indian Ocean has motivated the application of new technologies to deliver higher-resolution observations and models of Indian Ocean processes. As a result we are discovering the importance of small-scale processes in setting the large-scale gradients and circulation, interactions between physical and biogeochemical processes, interactions between boundary currents and the interior, and interactions between the surface and the deep ocean. A newly discovered regional climate mode in the southeast Indian Ocean, the Ningaloo Niño, has instigated more regional air–sea coupling and marine heatwave research in the global oceans. In the last decade, we have seen rapid warming of the Indian Ocean overlaid with extremes in the form of marine heatwaves. These events have motivated studies that have delivered new insight into the variability in ocean heat content and exchanges in the Indian Ocean and have highlighted the critical role of the Indian Ocean as a clearing house for anthropogenic heat. This synthesis paper reviews the advances in these areas in the last decade.

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