Author: S. A. ThorpePublisher:
ISBN:
Category : Turbulent boundary layer
Languages : en
Pages :
Book Description
The Dynamics of the Boundary Layers of the Deep Ocean
Author: S. A. ThorpePublisher:
ISBN:
Category : Turbulent boundary layer
Languages : en
Pages :
Book Description
The Dynamics of the Bottom Boundary Layer of the Deep Ocean
Author: Laurence ArmiPublisher:
ISBN:
Category :
Languages : en
Pages : 17
Book Description
Profiles of salinity and temperature from the center of the Hatteras Abyssal Plain have a signature that is characteristic of mixing up a uniformly stratified region: a well-mixed layer above the bottom, bounded by an interface. The penetration height of the mixed-layer varies from about 10 m to 100 m and has been correlated by Armi and Millard (1976) with the one day mean velocity, inferred from current meters located above the bottom boundary layer. Here the dynamics of such layers is discussed. A model of entrainment and mixing for a flat bottom boundary layer is outlined; this model is however incomplete because too little is known of the structure of turbulence above an ekman layer.
Boundary Layer Dynamics
Author: National Research CouncilPublisher: National Academies Press
ISBN: 0309057426
Category : Science
Languages : en
Pages : 49
Book Description
Boundary Layer Dynamics and Deep Ocean Mixing in Mid-Atlantic Ridge Canyons
Author: Rebecca Walsh DellPublisher:
ISBN:
Category : Abyssal zone
Languages : en
Pages : 163
Book Description
Physical oceanographers have known for several decades the total amount of abyssal mixing and upwelling required to balance the deep-water formation, but are still working to understand the mechanisms and locations-how and where it happens. From observational studies, we know that areas of rough topography are important and the hundreds of Grand-Canyon sized canyons that line mid-ocean ridges have particularly energetic mixing. To better understand the mechanisms by which rough topography translates into energetic currents and mixing, I studied diffusive boundary layers over varying topography using theoretical approaches and idealized numerical simulations using the ROMS model. In this dissertation, I show a variety of previously unidentified characteristics of diffusive boundary layers that are likely relevant for understanding the circulation of the abyssal ocean. These boundary layers share many important properties with observed flows in abyssal canyons, like increased kinetic energy near topographic sills and strong currents running from the abyssal plains up the slopes of the mid-ocean ridges toward their crests. They also have a previously unknown capacity to accelerate into overflows for a variety of oceanographically relevant shapes and sizes of topography. This acceleration happens without external forcing, meaning such overflows may be ubiquitous in the deep ocean. These boundary layers also can force exchange of large volumes of fluid between the relatively unstratified boundary layer and the stratified far-field fluid, altering the stratification far from the boundary. We see these effects in boundary layers in two- and three-dimensions, with and without rotation. In conclusion, these boundary layer processes, though previously neglected, may be a source of a dynamically important amount of abyssal upwelling, profoundly affecting predictions of the basin-scale circulation. This type of mechanism cannot be captured by the kind of mixing parameterizations used in current global climate models, based on a bottom roughness. Therefore, there is much work still to do to better understand how these boundary layers behave in more realistic contexts and how we might incorporate that understanding into climate models.
Dynamics of Nonlinear Cross-equatorial Flow in the Deep Ocean
Author: Christopher Andrew EdwardsPublisher:
ISBN:
Category : Ocean circulation
Languages : en
Pages : 716
Book Description
The transformation of potential vorticity within and stability of nonlinear deep western boundary currents in an idealized tropical ocean are studied using a shallowwater model. Observational evidence indicates that the potential vorticity of fluid parcels in deep western boundary currents must change sign as they cross the equator, but this evidence is otherwise unable to clarify the process. A series of numerical experiments investigate this transformation in a rectangular basin straddling the equator. A mass source located in the northwestern corner feeds fluid into the domain where it is constrained to cross the equator to reach a distributed mass sink. Dissipation is included as momentum diffusion. The Reynolds number, defined as the ratio of the mass source per unit depth to the viscosity, determines the nature of the flow, and a critical value, Rec, divides its possible behavior into two regimes. For Re
The Near-Surface Layer of the Ocean
Author: Alexander SolovievPublisher: Springer Science & Business Media
ISBN: 1402040539
Category : Science
Languages : en
Pages : 586
Book Description
Until the 1980s, a tacit agreement among many physical oceanographers was that nothing deserving attention could be found in the upper few meters of the ocean. The lack of adequete knowledge about the near-surface layer of the ocean was mainly due to the fact that the widely used oceanographic instruments (such as bathythermographs, CTDs, current meters, etc.) were practically useless in the upper few meters of the ocean. Interest in the ne- surface layer of the ocean rapidly increased along with the development of remote sensing techniques. The interpretation of ocean surface signals sensed from satellites demanded thorough knowledge of upper ocean processes and their connection to the ocean interior. Despite its accessibility to the investigator, the near-surface layer of the ocean is not a simple subject of experimental study. Random, sometimes huge, vertical motions of the ocean surface due to surface waves are a serious complication for collecting quality data close to the ocean surface. The supposedly minor problem of avoiding disturbances from ships’ wakes has frustrated several generations of oceanographers attempting to take reliable data from the upper few meters of the ocean. Important practical applications nevertheless demanded action, and as a result several pioneering works in the 1970s and 1980s laid the foundation for the new subject of oceanography – the near-surface layer of the ocean.
Deep Convection and Deep Water Formation in the Oceans
Author: Simon ChuPublisher: Elsevier
ISBN: 0080870953
Category : Science
Languages : en
Pages : 395
Book Description
This book contains articles presenting current knowledge about the formation and renewal of deep waters in the ocean. These articles were presented at an international workshop at the Naval Postgraduate School in Monterey in March 1990. It is the first book entirely devoted to the topic of deep water formation in which articles have been both selected and reviewed, and it is also the first time authors have addressed both surface and deep mixed layers. Highlighted are: past and recent observations (description and analysis), concepts and models, and modern techniques for future research. Thanks to spectacular advances realised in computing sciences over the last twenty years this volume includes a number of sophisticated numerical models. Observational as well as theoretical studies are presented and a clear distinction is established between open-ocean deep convection and shelf processes, both leading to deep- and bottom-water formation. The main subject addressed is the physical mechanism by which the deep water in the ocean can be renewed. Ventilation occurs at the surface in areas called the gills, where water is mixed and oxygenated before sinking and spreading in the abyss of the deep ocean. This phenomenon is a very active area for both experimentalists and theoreticians because of its strong implications for the understanding of the world ocean circulation and Earth climate. This major theme sheds light on specific and complex processes happening in very restricted areas still controlling three quarters of the total volume of the ocean. All articles include illustrations and a bibliography. This book will be of particular interest to physical oceanographers, earth scientists, environmentalists and climatologists.
Ocean Boundary Layer Dynamics and Air-sea Interaction
Author: Jacob O. WenegratPublisher:
ISBN:
Category : Boundary layer (Meteorology)
Languages : en
Pages : 168
Book Description
The dynamics of the ocean surface boundary layer are examined using theory, high-resolution moored observations from the equatorial Atlantic ocean, and idealized modeling. An approximate solution is found for the ocean response to wind-forcing in the presence of baroclinic pressure gradients, surface wave shear, and spatially varying turbulent mixing. The manner in which these parameters modify the classic physical model of the wind-forced ocean is discussed, and estimates of their spatial distribution are provided. Next, the role of time-varying shear in determining the near-surface eddy viscosity is assessed using velocity observations from the equatorial Atlantic, and the implications for several simple parameterizations are considered. These observations are then utilized to provide a first in situ observational assessment of the diurnal cycle of shear and stratification in the equatorial Atlantic, demonstrating how mixed-layer dynamics modulate the diurnal cycle of sea surface temperature, coupling the dynamic and thermodynamic responses. Further, these results suggest the existence of a deep-cycle turbulence layer in the equatorial Atlantic, providing a complementary perspective on similar recent work from the Pacific. Finally, the effect of time-varying eddy viscosity on the low-frequency wind-driven flow is assessed using theory and idealized modeling, providing a new conceptual tool for understanding the dynamics of the near-surface ocean, and for guiding the interpretation of observations. A particular focus throughout this thesis is the role of ocean dynamics in determining the near-surface ocean response to surface atmospheric fluxes.
The Benthic Boundary Layer
Author: Bernard P. BoudreauPublisher: Oxford University Press
ISBN: 9780199770915
Category : Science
Languages : en
Pages : 430
Book Description
The benthic boundary layer is the zone of water and sediment immediately adjacent to the bottom of a sea, lake, or river. This zone is of considerable interest to biologists, geochemists, sedimentologists, and engineers because of very strong gradients of energy, dissolved and solid chemical components, suspended matter, and the number of organisms that live there. It is, for example, the sink for anthropogenic substances and the home of microscopic plant life that provides the nutrients that determine fish populations--and ultimately the size of the fisheries. This book of original chapters edited by Professors Boudreau and Jorgensen, both leading researchers in the field, will meet the need for an up-to-date, definitive text/reference on measurements, techniques, and models for transport and biochemical processes in the benthic boundary layer. Each chapter provides a comprehensive review of a selected field, with illustrated examples from the authors' own work. The book will appeal to professionals and researchers in marine biology, marine chemistry, marine engineering, and sedimentology.
Author: Jungtsun Yean