Oceanic Internal Tides: Observations, Analysis and Modeling

A Global View

verfasst von: Dr. Eugene G. Morozov

Verlag: Springer International Publishing

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

This book presents a detailed study of the structure and variability of internal tides and their geographical distribution in the ocean. Based on experimental analysis of oceanic measurements combined with numerical modeling, it offers a comprehensive overview of the internal wave processes around the globe. In particular, it is based on moored buoys observations in many regions in all oceans (Atlantic, Pacific, Indian, Arctic, and Southern) that have been carried out by researchers from different countries for more than 40 years as part of various oceanographic programs, including WOCE and CLIVAR. However, a significant portion of the data was collected by the author, who is a field oceanographer. The data was processed and interpreted on the basis of the latest knowledge of internal wave motion. The properties of internal waves were analyzed in relation to the bottom topography and mean state of the ocean in specific regions.

Internal waves play a major role in the formation of seawater stratification and are responsible for the main processes of ocean dynamics, such as energy transfer and mixing. One of the most significant ideas presented in this book is the generation of internal tides over submarine ridges. Energy fluxes from submarine ridges related to tidal internal waves greatly exceed the fluxes from continental slopes. Submarine ridges form an obstacle to the propagation of tidal currents, which can cause the creation of large amplitude internal tides. Energy fluxes from submarine ridges account for approximately one fourth of the total energy dissipation of the barotropic tides. Model simulations and moored measurements have been combined to generate a map of global distribution of internal tide amplitudes.

This book is of interest to oceanographers, marine biologists, civil engineers, and scientists working in climate research, fluid mechanics, acoustics, and underwater navigation.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Modern Concepts About Oceanic Internal Waves

Abstract

This chapter describes the modern concepts about oceanic internal waves. It presents the mathematical formulation of the internal motion in the ocean. Since the book is mainly the result of the experimental analysis of oceanic measurements the processing tools for the measurements of field data are presented here together with the description of the Vlasenko numerical model for the generation, propagation, and dissipation of internal tides. The Garrett and Munk spectral background model is also described because this is important for understanding the internal motion despite the fact that it does not describe internal tides. Mechanisms of internal tide generation are analyzed and general notes on internal wave motion are presented.

Eugene G. Morozov

Chapter 2. Observations of Internal Tides in the Atlantic Ocean

Abstract

This chapter describes the measurements of internal tides in the Atlantic Ocean and in the Mediterranean Sea together with modeling of the generation and propagation of internal tides in some important regions of the Atlantic Ocean. The generation of internal tides is associated with the interaction of the currents of the barotropic tide with the slopes of the bottom topography. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. The generation and propagation of internal tides in the Strait of Gibraltar where the strongest internal tides on the globe exist are described. The generation of internal tides over the Mid-Atlantic Ridge in the South Atlantic is demonstrated on the basis of measurements in several regions near the ridge. The measurements reveal strong internal tides in Biscay Bay. Weaker internal tides are found in the Sargasso Sea. Measurements of internal tides on mooring clusters confirm the well known fact that internal tides are generated over the bottom slopes.

Eugene G. Morozov

Chapter 3. Observations of Internal Tides in the Pacific Ocean

Abstract

This chapter describes the measurements of internal tides in the Pacific Ocean together with modeling of the generation and propagation of internal tides in some important regions of the Pacific. The generation of internal tides is associated with the interaction of the currents of the barotropic tide with the slopes of the bottom topography. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. The generation and propagation of strong internal tides over the Aleutian and Hawaiian ridges and in the South China Sea are described. The generation of internal tides in the regions of internal tides that are of high but still lower energy than those near the Aleutian Islands is revealed over the Kyushu-Palau and Emperor ridges and over the Mendocino Escarpment. Attention is focused on the measurements of internal tides in the Northwest Pacific where the Megapolygon experiment was conducted with 173 moorings. Measurements of internal tides on mooring clusters confirm the well known fact that internal tides are generated over the bottom slopes. The propagation of beams of internal tides from the top of a seamount was found in the East Pacific.

Eugene G. Morozov

Chapter 4. Observations of Internal Tides in the Indian Ocean

Abstract

This chapter describes the measurements of internal tides in the Indian Ocean together with modeling of the generation and propagation of internal tides in some important regions of the Indian Ocean. The generation of internal tides is associated with the interaction of the currents of the barotropic tide with the slopes of the bottom topography. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. The generation and propagation of strong internal tides over the Mascarene Ridge are analyzed. The generation and propagation of internal tides in the Bab el Mandeb Strait where very strong internal tides exist are described. Strong internal tides are also found in the Madagascar Strait. Measurements of internal tides on mooring clusters confirm the well known fact that internal tides are generated over the bottom slopes.

Eugene G. Morozov

Chapter 5. Observations of Internal Tides in the Southern Ocean

Abstract

This chapter describes the measurements of internal tides in the Southern Ocean. The generation of internal tides is associated with the interaction of the currents of the barotropic tide with the slopes of the bottom topography. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. There are not so many field measurements in the Southern Ocean as in the other oceans. Only the Drake Passage is well covered with measurements. No strong generators of internal tides exist here. Measurements of internal tides on mooring clusters confirm the well known fact that internal tides are generated over the bottom slopes. Some of the regions of field measurements are located south of the critical latitude (74° 30′S) so that semidiurnal internal tides rapidly decay with the distance from the bottom slopes.

Eugene G. Morozov

Chapter 6. Observations of Internal Tides in the Arctic Ocean

Abstract

This chapter describes the measurements of internal tides in the Arctic Ocean. Most of the regions of field measurements are located north of the critical latitude (74° 30′N) so that semidiurnal internal tides rapidly decay with the distance from the bottom slopes. The generation of internal tides is associated with the interaction of the currents of the barotropic tide with the slopes of the bottom topography. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. The chapter begins with general notes on internal tides in the Arctic region whose major part in located north of the critical latitude. Measurements of internal tides on mooring clusters confirm the well known fact that internal tides are generated over the bottom slopes. Internal tides rapidly decay with the distance from submarine slopes (74° 30′N). Strong generation of internal tides was found in the Strait of Kara Gates between the Barents and Kara seas. The existence of permanent polynyas in the Laptev Sea is associated with internal tides over the continental shelf. Properties of internal tides measured near the North Pole are described.

Eugene G. Morozov

Chapter 7. Properties of Internal Tides

Abstract

This chapter describes some important properties of internal tides. The diurnal and semidiurnal spectral peaks related to the internal tides consist of separate waves with close frequencies. Internal tides are modulated due to the spring-neap variability of the barotropic tide that generates them. Strong internal tides usually have mode structure, which is considered here on the basis of field measurements. Fluctuations of currents at a semidiurnal frequency consist of the currents induced by the barotropic tide and internal tide. The methods for separating them are considered. The beam propagation of internal tides near the generation regions of submarine slopes is considered. The long distance propagation of internal tides and decay of their energy are analyzed based on observations and modeling. Mixing induced by internal tides influences the propagation of Antarctic Bottom Water to the north in the Atlantic Ocean.

Eugene G. Morozov

Chapter 8. Semidiurnal Internal Wave Global Field; Global Estimates of Internal Tide Energy

Abstract

This chapter describes the semidiurnal internal wave global field and global estimates of internal tide energy. One of the most important ideas presented here is the strong generation of internal tides over submarine ridges. Energy fluxes from submarine ridges related to tidal internal waves exceed many times the fluxes from continental slopes. Submarine ridges form an obstacle to the propagation of tidal currents that provides internal tide generation because tidal currents obtain a vertical component over the ridge slopes. Energy fluxes from submarine ridges account for approximately one fourth of the total energy dissipation of the barotropic tides. Combined model simulations and moored measurements result in a map of the global distribution of internal tide amplitudes.

Eugene G. Morozov

Backmatter

Titel: Oceanic Internal Tides: Observations, Analysis and Modeling
verfasst von: Dr. Eugene G. Morozov
Verlag: Springer International Publishing
Electronic ISBN: 978-3-319-73159-9
Print ISBN: 978-3-319-73158-2
DOI: https://doi.org/10.1007/978-3-319-73159-9