The Third Edition builds a solid foundation that readers will find straightforward and lucid. The book is organized into three parts. Part I on descriptive oceanography covers topics such as nature of oceanographic data, the chemical nature of the ocean, the temperature of the ocean, and temperature-salinity relationships. Part III covers various topics such as sound propagation, the heat budget of the ocean, and estuaries.
This book aims to provide the non-physical oceanographer with insight into the physical nature of the environment influencing his chosen studies. The physical oceanographer will be somewhat less than satisfied with the treatment and will wish to read the publications referred to and to follow the suggestions for additional reading.
It aims to present the basic objectives, procedures and successes and to state some of the present limitations of dynamical oceanography and its relations to descriptive physical oceanography. The first edition has been thoroughly revised and updated and the new work includes reference to the Practical Salinity Scale , the International Equation of State and the beta-spiral technique for calculating absolute currents from the density distribution.
Passive margins, like those of the Atlantic, are being pushed in front of spreading seafloor, are accumulating thick wedges of sediment, and are generally falling. Coasts can be referred to as erosional or depositional depending on whether materials are removed or added. At shorter timescales, waves and tides cause erosion and deposition.
At millennial timescales, changes in mean sea level cause materials to be removed or added. Erosional coasts are attacked by waves and currents, both of which carry fine material that abrades the coast. The waves create alongshore and rip currents Section 8. This eroded material can be joined by sediments discharged from rivers and form. This type of erosion is fastest on highenergy coasts with large waves, and slowest on low-energy coasts with generally weak wave fields.
Erosion occurs more rapidly in weaker materials than in harder components. These variations in materials allow erosive forces to carve characteristic features on coastlines such as sea cliffs and sea caves, and to create an alternation between bays and headlands. Beaches result when sediment, usually sand, is transported to places suitable for continued deposition. Again these are often the quiet bays between headlands and other areas of low surf activity.
Often a beach is in equilibrium; new sand is deposited to replace sand that is scoured away. Evidence for this process can be seen by how sand accumulates against new structures built on the shore, or by how it is removed from a beach when a breakwater is built that cuts off the supply of sand beyond it. On some beaches, the sand may be removed by currents associated with high waves at one season of the year and replaced by different currents associated with lower waves at another season.
These currents are influenced by seasonal and interannual wind variations. Changes in the total amount of water are due primarily to changes in the volume of landfast ice, which is contained in ice sheets and glaciers. Because sea ice floats in water, changes in sea ice volume, such as that in the Arctic or Antarctic, do not affect sea level.
Changes in containment volume are due to tectonics, the slow rebound of continents continuing into the present after the melt of landfast ice after the last deglaciation, and rebound due to the continuing melt of glacial ice. Changes in heat content cause seawater to expand heating or contract cooling. Sea level rose 20 cm from to , including 3 cm in just the last 10 years e Because good global observations are available for that last 10 years, it is possible to ascribe 1.
See Bindoff et al. Its outer limit the shelf break is set where the gradient increases to about 1 in 20 on average to form the continental slope down to the deep sea bottom. The shelf has an average width of 65 km. In places it is much narrower than this, while in others, as in the northeastern Bering Sea or the Arctic shelf off Siberia, it is as much as ten times this width.
The bottom material is dominantly sand with less common rock or mud. The shelf break is usually clearly evident in a vertical cross-section of the sea bottom from the shore outward. The average depth at the shelf break is about m. Most of the worlds fisheries are located on the continental shelves for a multitude of reasons including proximity of estuaries, depth of penetration of sunlight compared with bottom depth, and upwelling of nutrient-rich waters onto some shelves, particularly those off western coasts.
The continental slope averages about m vertically from the shelf to the deep-sea bottom, but in places extends as much as m vertically in a relatively short horizontal distance. In general, the continental slope is considerably. The material of the slope is predominantly mud with some rock outcrops. The shelf and slope typically include submarine canyons, which are of worldwide occurrence. These are valleys in the slope, either V-shaped or with vertical sides, and are usually found off coasts with rivers.
Some, usually in hard granitic rock, were originally carved as rivers and then submerged, such as around the Mediterranean and southern Baja, California. Others, commonly in softer sedimentary rock, are formed by turbidity currents described in the next paragraph. The lower part of the slope, where it grades into the deep-sea bottom, is referred to as the continental rise.
Turbidity currents Figure 2. These episodic events carry a mixture of water and sediment and are driven by the unstable sediments rather than by forces within the water. In these events, material builds up on the slope until it is no longer stable and the force of gravity wins out. These events can snap underwater cables.
The precise conditions that dictate when a turbidity current occurs vary with the slope of the valley and the nature of the material in the valley. Turbidity currents carve many of the submarine canyons found on the slopes. Some giant rivers, such as the Congo, carry such a dense load of suspended material that they form continuous density flows of turbid water down their canyons.
DEEP OCEAN From the bottom of the continental slope, the bathymetric gradient decreases down the continental rise to the deep-sea bottom, the last and most extensive area. Perhaps the most characteristic. Source: From Heezen, Ericson, and Ewing Before any significant deep ocean soundings were available, the sea bottom was regarded as uniformly smooth. When detailed sounding started in connection with cable laying, it became clear that this was not the case and there was a swing to regarding the sea bottom as predominantly rugged.
With the advent of satellite altimetry for mapping ocean topography, we now have an excellent global view of the distribution of all of these features e. A sill is a ridge, above the average bottom level in a region, which separates one basin from another or, in the case of a fjord Section 5. The sill depth is the depth from the sea surface to the deepest part of the ridge; that is, the maximum depth at which direct flow across the sill is possible.
An oceanic sill is like a topographic saddle with the sill depth analogous to the saddlepoint. In the deep ocean, sills connect deep basins. The sill depth controls the density of waters that can flow over the ridge. Straits, passages, and channels are horizontal constrictions. It is most common to refer to a strait when considering landforms, such as the Strait of Gibraltar that connects the Mediterranean Sea and the Atlantic Ocean, or the Bering Strait that connects the Bering Sea and the Arctic Ocean.
Passages and channels can also refer to submarine topography, such as in fracture zones that connect deep basins. Straits and sills can occur together, as in both of these examples. The minimum width of the strait and the maximum depth of the sill can hydraulically control the flow passing through the constriction. The early measurements were made by lowering a weight. This method was slow; in deep water it was uncertain because it was difficult to tell when the weight touched the bottom and if the line was vertical.
Since most depth measurements have been made with echo sounders, which measure the time taken for a pulse of sound to travel from the ship to the bottom and reflect back to the ship. One half of this time is multiplied by the average speed of sound in the seawater under the ship to give the depth.
With presentday equipment, the time can be measured very accurately and the main uncertainty over a flat bottom is in the value used for the speed of sound.
This varies with water temperature and salinity see Section 3. Research and military ships are generally outfitted with echo sounders and routinely report their bathymetric data to data centers that compile the information for bathymetric mapping. The bathymetry along the research ship track in Figure 2. The modern extension of these single echo sounders is a multi-beam array, in which many sounders are mounted along the bottom of the ship; these provide two-dimensional swath mapping of the seafloor beneath the ship.
Great detail has been added to our knowledge of the seafloor topography by satellite measurements. These satellites measure the earths gravity field, which depends on the local mass of material. Echo sounder measurements are still needed to verify the.
The bathymetry shown in Figure 2. The material of the deep-sea bottom is often more fine-grained than that on the shelf or slope. Much of it is pelagic in character, that is, it has been formed in the open ocean. The two major deep ocean sediments are red clay and the biogenic oozes. It consists of fine material from the land which may have traveled great distances through the air before finally settling into the ocean , volcanic material, and meteoric remains.
The calcareous oozes have a high percentage of calcium carbonate from the shells of animal plankton, while the siliceous oozes have a high proportion of silica from the shells of silica-secreting planktonic plants and animals. The siliceous oozes are found mainly in the Southern Ocean and in the equatorial Pacific. The relative distribution of calcareous and siliceous oozes is clearly related to the nutrient content of the surface waters, with calcareous oozes common in low nutrient regions and siliceous oozes in high nutrient regions.
Except when turbidity currents deposit their loads on the ocean bed, the average rate of deposition of the sediments is from 0. Samples of bottom material are obtained with a corer, which is a 2e30 m long steel pipe that is lowered vertically and forced to penetrate into the sediments by the heavy weight at its upper end.
The core of sediment retained in the pipe may represent material deposited from to 10 million years per meter of length. Sometimes the material is layered, indicating stages of sedimentation of different materials.
In some places, layers of volcanic ash are related to historical records of eruptions; in others, organisms characteristic of cold or warm waters are found in different layers and suggest changes in temperature of the overlying water during the period represented by the core.
In some places gradations from coarse to fine sediments in the upward direction suggest the occurrence of turbidity currents bringing material to the region with the coarser material settling out first and the finer later. Large sediment depositions from rivers create a sloping, smooth ocean bottom for thousands of miles from the mouths of the rivers. This is called a deep-sea sediment fan. The largest, the Bengal Fan, is in the northeastern Indian Ocean and is created by the outflow from many rivers including the Ganges and Brahmaputra.
Other examples of fans are at the mouths of the Yangtze, Amazon, and Columbia Rivers. Physical oceanographers use sediments to help trace movement of the water at the ocean floor. Some photographs of the deep-sea bottom show ripples similar to a sand beach after the tide has gone out. Such ripples are only found on the beach where the water speed is high, such as in the backwash from waves. We conclude from the ripples on the deep-ocean bottom that currents of similar speed occur there.
This discovery helped to dispel the earlier notion that all deep-sea currents are very slow. Sediments can affect the properties of seawater in contact with them; for instance,. Organic carbon, mainly from fecal pellets, is biologically decomposed remineralized into inorganic carbon dioxide in the sediments with oxygen consumed in the process.
The carbon dioxiderich, oxygen-poor pore waters in the sediments are released back into the seawater, affecting its composition. Organic nitrogen and phosphorus are also remineralized in the sediments, providing an important source of inorganic nutrients for seawater.
In regions where all oxygen is consumed, methane forms from bacterial action. This methane is often stored in solid form called a methane hydrate. Vast quantities about g of methane hydrate have accumulated in marine sediments over the earths history. They can spontaneously turn from solid to gaseous form, causing submarine landslides and releasing methane into the water, affecting its chemistry.
To the north there is a physical boundary broken only by the Bering Strait, which is quite shallow about 50 m and 82 km wide. There is a small net northward flow from the Pacific to the Arctic through this strait.
At the equator, the Pacific is very wide so that tropical phenomena that propagate east-west take much longer to cross the Pacific than across the other oceans. The Pacific is rimmed in the west and north with trenches and ridges. This area, because of the associated volcanoes, is called the ring of fire. The EPR, a major topographic feature of the tropical and South Pacific, is a spreading ridge that separates the deep waters of the southeast from the rest of the Pacific; it is part of the global mid-ocean ridge Section 2.
Fracture zones allow some communication of deep waters across the ridge. Where the major eastward current of the. The Pacific has more islands than any other ocean. Most of them are located in the western tropical regions. The Hawaiian Islands and their extension northwestward into the Emperor Seamounts were created by motion of the Pacific oceanic plate across the hotspot that is now located just east of the big island of Hawaii.
The Pacific Ocean has numerous marginal seas, mostly along its western side. In the South Pacific the marginal seas are the Coral and Tasman Seas and many smaller distinct regions that are named, such as the Solomon Sea not shown. In the southern South Pacific is the Ross Sea, which contributes to the bottom waters of the world ocean. The Atlantic Ocean has an S shape Figure 2. The MAR, a spreading ridge down the center of the ocean, dominates its topography.
Deep trenches are found just east of the Lesser Antilles in the eastern Caribbean and east of the South Sandwich Islands. The Atlantic is open both at the north and the south connecting to the Arctic and Southern Oceans. The northern North Atlantic is one of the two sources of the worlds deep water Chapter 9. One of the Atlantics marginal seas, the Mediterranean, is evaporative and contributes high salinity, warm water to the mid-depth ocean.
At the southern boundary, the Weddell Sea is a major formation site for the bottom water found in the oceans Chapter Fresh outflow.
The Indian Ocean Figure 2. The topography of the Indian Ocean is very rough because of the ridges left behind as the Indian plate moved northward into the Asian continent creating the Himalayas. As discussed previously, seafloor roughness from abyssal hills and fracture zones is highest at slower spreading rates, which is necessary in understanding the spatial distribution of deep mixing in the global ocean.
The only trench is the Sunda Trench. The eastern boundary of the Indian Ocean is porous and connected to the Pacific Ocean through the Indonesian archipelago.
The open ocean region west of India is called the Arabian Sea and the region east of India is called the Bay of Bengal. The differential heating of land and ocean in the tropics results in the creation of the monsoon weather system.
Monsoons occur in many places, but the most dramatic and best described monsoon is in the northern Indian Ocean Chapter From October to May the Northeast Monsoon sends cool, dry winds from the.
Starting in June and lasting until September, the system shifts to the southwest monsoon, which brings warm, wet rains from the western tropical ocean to the Indian subcontinent. While these. Most of the rivers that drain southward from the Himalayas d including the Ganges, Brahmaputra, and Irawaddy d flow out into the. This causes the surface water of the Bay of Bengal to be quite fresh. The enormous amount of silt carried by these rivers from the eroding Himalayan Mountains into the Bay of Bengal creates the subsurface geological feature, the Bengal Fan, which slopes smoothly downward for thousands of.
Similar to the Mediterranean, the saline Red Sea water is sufficiently dense to sink to middepth in the Indian Ocean and affects water properties over a large part of the Arabian Sea and western Indian Ocean. The Arctic Ocean Figure 2. It is characterized by very broad continental shelves surrounding a deeper region, which is split down the center by the Lomonosov Ridge.
Kara, and Barents Seas. Dense water formed in the Nordic Seas spills into the Atlantic over this ridge. The central area of the Arctic Ocean is perennially covered with sea ice. The Southern Ocean Figure 2. Indian, and Pacific Oceans, but is often considered separately since it is the only region outside the Arctic where there is a path for eastward flow all the way around the globe.
This occurs at the latitude of Drake Passage between South America and Antarctica and allows the three major oceans to be connected. The absence of a meridional north-south.
Drake Passage also serves to constrict the width of the flow of the ACC, which must pass in its entirety through the passage. The South Sandwich Islands and trench east of Drake Passage partially block the open circumpolar flow.
Another major constriction is the broad Pacific-Antarctic rise, which is the seafloor spreading ridge between the Pacific and Antarctic plates. This fast-spreading ridge has few deep fracture zones, so the ACC must.
The ocean around Antarctica includes permanent ice shelves as well as seasonal sea ice Figures Unlike the Arctic there is no perennial long-term pack ice; except for some limited ice shelves and all of the firstyear ice melts and forms each year.
The densest bottom waters of the world ocean are formed in the Southern Ocean, primarily in the Weddell and Ross Seas as well as in other areas distributed along the Antarctic coast between the Ross Sea and Prydz Bay.
As seawater is heated, molecular activity increases and thermal expansion occurs, reducing the density. In seawater, these molecular effects are combined with the influence of salt, which inhibits the formation of the chains. Water has a very high heat of evaporation or heat of vaporization and a very high heat of fusion. The heat of vaporization is the amount of energy required to change water from a liquid to a gas; the heat of fusion is the amount of energy required to change water from a solid to a liquid.
These quantities are relevant for our climate as water changes state from a liquid in the ocean to water vapor in the atmosphere and to ice at polar latitudes. The heat energy. Many of the unique characteristics of the ocean can be ascribed to the nature of water itself.
Consisting of two positively charged hydrogen ions and a single negatively charged oxygen ion, water is arranged as a polar molecule having positive and negative sides. This molecular polarity leads to waters high dielectric constant ability to withstand or balance an electric field. Water is able to dissolve many substances because the polar water molecules align to shield each ion, resisting the recombination of the ions.
The oceans salty character is due to the abundance of dissolved ions. The polar nature of the water molecule causes it to form polymer-like chains of up to eight molecules. Energy is required to produce these chains, which is related to waters heat capacity. Water has the highest heat capacity of all liquids except ammonia. This high heat capacity is the primary reason the ocean is so important in the world climate system.
Unlike the land and atmosphere, the ocean stores large amounts of heat energy it receives from the sun. This heat is carried by ocean currents, exporting or importing heat to various regions. Waters chain-like molecular structure also produces its high surface tension. The chains resist shear, giving water a high viscosity for its atomic weight. This high viscosity permits formation of surface capillary waves, with wavelengths on the order of centimeters; the restoring forces for these waves include surface tension as well as gravity.
Despite their small size, capillary waves are important in determining the frictional stress between wind and water. This stress generates larger waves and propels the frictionally driven circulation of the oceans surface layer.
A special unit for. Ocean pressure is usually reported in decibars where 1 dbar 0. The force due to pressure arises when there is a difference in pressure between two points. The force is directed from high to low pressure.
Hence we say the force is oriented down the pressure gradient since the gradient is directed from low to high pressure. In the ocean, the downward force of gravity is mostly balanced by an upward pressure gradient force; that is, the water is not accelerating downward. Instead, it is kept from collapsing by the upward pressure gradient force. Therefore pressure increases with increasing depth. This balance of downward gravity force and upward pressure gradient force, with no motion, is called hydrostatic balance Section 7.
The pressure at a given depth depends on the mass of water lying above that depth. A pressure change of 1 dbar occurs over a depth change of slightly less than 1 m Figure 3. Pressure in the ocean thus varies from near zero surface to 10, dbar deepest.
TABLE 3. The properties are often presented as a function of pressure rather than depth. Horizontal pressure gradients drive the horizontal flows in the ocean. For large-scale currents of horizontal scale greater than a kilometer , the horizontal flows are much stronger than their associated vertical flows and are usually geostrophic Chapter 7. The horizontal pressure differences that drive the ocean currents are on the order of one decibar over hundreds or thousands of kilometers.
This is much smaller than the vertical pressure gradient, but the latter is balanced by the downward force of gravity and does not drive a flow. Horizontal variations in mass distribution create the horizontal variation in pressure in the ocean. The pressure is greater where the water column above a given depth is heavier either because it is higher density or because it is thicker or both.
Pressure is usually measured with an electronic instrument called a transducer. The accuracy and precision of pressure measurements is high enough that other properties such as temperature, salinity, current speeds, and so forth can be displayed as a function of pressure. However, the accuracy, about 3 dbar at depth, is not sufficient to measure the horizontal pressure gradients.
Therefore other methods, such as the geostrophic method, or direct velocity measurements, must be used to determine the actual flow. Prior to the s and s, pressure was measured using a pair of mercury thermometers, one of which was in a vacuum protected by a glass case and not affected by pressure while the other was exposed to the water unprotected and affected by pressure, as described in the following section.
More information about these instruments and methods is provided in Section S6. Temperature was one of the first ocean parameters to be measured and remains the most widely observed.
In most of the ocean, temperature is the primary determinant of density; salinity is of primary importance mainly in high latitude regions of excess rainfall or sea ice processes Section 5. In the mid-latitude upper ocean between the surface and m , temperature is the primary parameter determining sound speed.
Temperature measurement techniques are described in Section S6. The relation between temperature and heat content is described in Section 3. As a parcel of water is compressed or expanded, its temperature changes.
The concept of potential temperature Section 3. Temperature Temperature is a thermodynamic property of a fluid, due to the activity or energy of molecules and atoms in the fluid. Temperature is higher for higher energy or heat content. Heat and temperature are related through the specific heat Section 3.
When the heat content is zero no molecular activity , the temperature is absolute zero on the Kelvin scale. The usual convention for meteorology is degrees Kelvin, except in weather reporting, since atmospheric temperature decreases to very low values in the stratosphere and above. This text is ideal for undergraduates and graduate students in marine sciences and oceanography. Expanded ocean basin descriptions, including ocean climate variability, emphasizing dynamical context New chapters on global ocean circulation and introductory ocean dynamics Companion website containing PowerPoint figures, supplemental chapters, and practical exercises for analyzing a global ocean data set using Java OceanAtlas.
The authors include historical and current research, along with a page color insert, to illuminate their perspective that the world ocean is tumultuous and continually helps to shape global environmental processes. The Third Edition builds a solid foundation that readers will find straightforward and lucid. The Arctic Mediterranean Sea has been intensively studied in recent years, especially during the fourth International Polar Year, —09, and we have become increasingly aware of the changes presently taking place.
The rapidly developing field of oceanography has necessitated the publication of a fifth edition of this classic textbook. The revised version provides an introduction to descriptive synoptic oceanography and contains updated information on topics such as the heat budget, instruments and in particular, the use of satellites. The sections on equatorial oceanography, sea-ice physics, distribution and El Nino have been completely rewritten.
The book is further supplemented by text on thermohaline circulation, mixing and also coral reef oceanography. There has been an updating of topics such as the heat budget, instruments particularly the use of satellites , a complete revision of the material on equatorial oceanography, sea-ice physics and distribution and El Nino and information has been added on thermohaline circulation, mixing nad coral reef oceanography. Descriptive Physical Oceanography, Sixth Edition, provides an introduction to the field with an emphasis on large-scale oceanography based mainly on observations.
Topics covered include the physical properties of seawater, heat and salt budgets, instrumentation, data analysis methods, introductory dynamics, oceanography and climate variability of each of the oceans and of the global ocean, and brief introductions to the physical setting, waves, and coastal oceanography.
This updated version contains ocean basin descriptions, including ocean climate variability, emphasizing dynamical context; new chapters on global ocean circulation and introductory ocean dynamics; and a new companion website containing PowerPoint figures, lecture and study guides, and practical exercises for analyzing a global ocean data set using Java OceanAtlas.
This text is ideal for undergraduates and graduate students in marine sciences and oceanography. Expanded ocean basin descriptions, including ocean climate variability, emphasizing dynamical context New chapters on global ocean circulation and introductory ocean dynamics Companion website containing PowerPoint figures, supplemental chapters, and practical exercises for analyzing a global ocean data set using Java OceanAtlas.
A translation of "Guide de conception et de gestion des reseaux d'assainissement unitaires", this text looks at the design and management of combined sewerage networks, covering topics such as: data on rainstorm run-off pollution; different types of weirs and accessories; and choice of weir. The authors include historical and current research, along with a page color insert, to illuminate their perspective that the world ocean is tumultuous and continually helps to shape global environmental processes.
The Third Edition builds a solid foundation that readers will find straightforward and lucid. It aims to present the basic objectives, procedures and successes and to state some of the present limitations of dynamical oceanography and its relations to descriptive physical oceanography. The first edition has been thoroughly revised and updated and the new work includes reference to the Practical Salinity Scale , the International Equation of State and the beta-spiral technique for calculating absolute currents from the density distribution.
In addition the description of mixed-layer models has been updated and the chapters on Waves and on Tides have been substantially revised and enlarged, with emphasis on internal waves in the Waves chapter. While the text is self-contained readers are recommended to acquaint themselves with the general aspects of descriptive synoptic oceanography in order to be aware of the character of the ocean which the dynamical oceanographer is attempting to explain by referring to Pickard and Emery's 'Descriptive Physical Oceanography' 4th edition.
Data Analysis Methods in Physical Oceanography is a practical reference guide to established and modern data analysis techniques in earth and ocean sciences.
This second and revised edition is even more comprehensive with numerous updates, and an additional appendix on 'Convolution and Fourier transforms'. Intended for both students and established scientists, the five major chapters of the book cover data acquisition and recording, data processing and presentation, statistical methods and error handling, analysis of spatial data fields, and time series analysis methods. Chapter 5 on time series analysis is a book in itself, spanning a wide diversity of topics from stochastic processes and stationarity, coherence functions, Fourier analysis, tidal harmonic analysis, spectral and cross-spectral analysis, wavelet and other related methods for processing nonstationary data series, digital filters, and fractals.
The seven appendices include unit conversions, approximation methods and nondimensional numbers used in geophysical fluid dynamics, presentations on convolution, statistical terminology, and distribution functions, and a number of important statistical tables.
Twenty pages are devoted to references. In praise of the first edition: " This is a very practical guide to the various statistical analysis methods used for obtaining information from geophysical data, with particular reference to oceanography The book provides both a text for advanced students of the geophysical sciences and a useful reference volume for researchers.
This is an excellent book that I recommend highly and will definitely use for my own research and teaching. Jay, "
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