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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
The scientific expedition of H.M.S. Challenger in the 1870s marks the starting point of physical oceanography. This ship traveled the seas of the globe pursuing a dual objective: to conduct an in-depth study of animal life and to observe the physical properties of ocean waters. Volume 2 analyzes and uses for the first time the physical measurements collected by the scientists of the Challenger to show that their surveys establish the link between ocean circulation and the distribution of the ocean's temperature. From Deep Sea to Laboratory is available in three volumes for curious readers drawn to travel, history and science. Students, researchers and teachers of physics, fluid mechanics and oceanography will find material to deepen their knowledge.
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Seitenzahl: 271
Veröffentlichungsjahr: 2019
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Table of Contents
Cover
Foreword
Preface
Notations
1 The Vertical Distribution of Temperature in the Ocean
1.1. Introduction
1.2. Measuring the temperature of ocean waters
1.3. Sources of errors in temperature measurement
2 Global Ocean Circulation
2.1. Introduction
2.2. Global ocean circulation
2.3. Conclusion and summary
3 A Brief Consideration of Thermocline Properties
3.1. Modeling of the thermocline
3.2. Assumptions used to solve the thermocline model
3.3. Characteristic properties of the thermocline
4 Effect of the Ocean Mixed Layer (OML)
4.1. Ocean mixed layer modeling
4.2. Coupling between the OML and the geostrophic layer
4.3. Seasonal fluctuations
4.4. Role of sea ice
4.5. Thermohaline circulation
Conclusion: Overview and Contributions of Physical Measurements Taken During the H.M.S. Challenger Expedition
References
Index
Summary of Volume 1
End User License Agreement
List of Tables
Chapter 1
Table 1.1. Law of correspondence between pressure and depth used by Captain J.E....
Chapter 3
Table 3.1. Definition and order of magnitude of parameters and numbers used for ...
Chapter 4
Table 4.1. Measurements carried out by the H.M.S. Challenger on the western marg...
Table 4.2. Measurements carried out by the H.M.S. Challenger on the oceanic long...
Table 4.3. Main surface currents contributing to the ocean circulation. The give...
Conclusion
Table C.1. Relationships of authors’ model for the thermocline
Table C.2. Relationships of authors’ model for the OML
List of Illustrations
Chapter 1
Figure 1.1. Map of surface ocean currents in the Atlantic. The red arrows repres...
Figure 1.2. Reading of the temperature according to the depth in the Mariana Tre...
Figure 1.3. Temperature profile in the Pacific Ocean following the meridian of l...
Figure 1.4. Statue of Balmat and Saussure watching Mont-Blanc in Chamonix (Franc...
Figure 1.5. Walferdin spill thermometer. View of the instrument during the measu...
Figure 1.6. Miller–Casella thermometer used aboard the Challenger. Figure Z repr...
Figure 1.7. Protective cover of Miller–Casella thermometers. This closed tubular...
Figure 1.8. Reversing Device of Georges Aimé. Representations of the device in d...
Figure 1.9. Negretti & Zambra reversing thermometer. (a) and (c) original model;...
Figure 1.10. Siemens electric thermometer. Overview of the device made around a ...
Figure 1.11. Minimum Thermometer of Cavendish. The upper end B is open and the m...
Figure 1.12. Illustration of the Corvette La Recherche near Bear Island,Spitzber...
Figure 1.13. Hydraulic press used aboard the H.M.S. Challenger. Water pump (A), ...
Figure 1.14. Change in density of freshwater according to the temperature at atm...
Figure 1.15. Internal piezometer used by Peter Tait for the high-pressure instru...
Figure 1.16. External manometer used by Peter Tait. External iron chamber (E) an...
Chapter 2
Figure 2.1. Change of maximum density temperature based on salinity [ROS 67, ROS...
Figure 2.2. Temperature profiles collected by the expedition of the H.M.S. Chall...
Figure 2.3. Representation of the ocean circulation in the rotating frame of ref...
Figure 2.4. Representation of the centrifugal force . The surface of the Earth ...
Figure 2.5. Plan view of the geostrophic current (Oxy plane). : geostrophic vel...
Figure 2.6. The geostrophic velocity related to the slope of the isobars. In t...
Figure 2.7. Link between Cartesian and spherical coordinates
Figure 2.8. Interpretation of Sverdrup relation for the Northern Hemisphere. Ana...
Figure 2.9. Planes tangent to the terrestrial sphere. Planes: horizontal (at the...
Figure 2.10. Model of “shallow-water”: u and v are independent of the variable z
Figure 2.11. Effect of a change of latitude on the variation of the relative vor...
Figure 2.12. Sign of relative vorticity for a curvilinear trajectory imposed in ...
Chapter 3
Figure 3.1. Schematic of the oceanic vertical layers. OML: ocean mixed layer, we...
Figure 3.2. Portion of ocean formed by two southern borders ΦO and ΦE
Figure 3.3. Examples of temperature, salinity and density measurements as a func...
Figure 3.4. Examples of ocean water temperature surveys as a function of depth a...
Figure 3.5. Change of the characteristic scale deduced from the measurements o...
Figure 3.6. Iso-depth curves deduced from the measurements of the H.M.S. Challen...
Figure 3.7. Isothermal curves deduced from the measurements of the H.M.S. Challe...
Figure 3.8. Change of the depth scale of the thermocline as a function of lati...
Figure 3.9. Typical appearances of temperature decrease as a function of depth. ...
Figure 3.10. Theoretical change of vertical velocity at the base of the thermocl...
Figure 3.11. Ocean surface and bottom temperatures and thermocline top TS an...
Figure 3.12. Representation of the isotherms in the Atlantic Ocean
Figure 3.13. Representation of the isotherms in the Pacific Ocean
Chapter 4
Figure 4.1. Diagram representing average speed of the wind depending on the lati...
Figure 4.2. Relationship between the mechanical stress of the wind and the direc...
Figure 4.3. Evolution of the parallel and perpendicular components of velocity s...
Figure 4.4. Evolution of the velocity vector specific to the mixed layer depen...
Figure 4.5. Horizontal Ekman transport specific to the mixed layer for a zonal...
Figure 4.6. Example of zonal representation of the wind depending on the norther...
Figure 4.7. Evolution of the vertical velocity at the base of the OML depending ...
Figure 4.8. Effect of wind on the movement of water masses in the subtropics. (a...
Figure 4.9. Effect of wind on the movement of water masses in the polar regions....
Figure 4.10. Map of the isotherms along the parallel of latitude 3°54’ north for...
Figure 4.11. Representation of east–west transport isolines for the water layer ...
Figure 4.12. Representation of the current lines for the two solutions correspon...
Figure 4.13. Schema representing convergences and divergences of the waters in t...
Figure 4.14. Representation of the Stommel model approximated by the relationshi...
Figure 4.15. Representation of the coordinates (x, y, z) of a β plane on the sph...
Figure 4.16. Vertical velocity at the base of the OML. Model corresponding to ...
Figure 4.17. Representation of the boundary conditions for the thermocline model...
Figure 4.18. Variation of , in the South Atlantic Ocean (AS) and in the North P...
Figure 4.19. Evolution of temperature difference at the top of the thermocline ...
Figure 4.20. Evolution of the temperature of the thermocline in the North Atlant...
Figure 4.21. Plot of isotherms along the 11°12’ meridian west in the North Atlan...
Figure 4.22. Map of the isotherms (in °C) along the 11°12’ meridian west for the...
Figure 4.23. Representation of the isotherms in the plane for a relative lon...
Figure 4.24. Change of temperature of the thermocline, on the western margin, ...
Figure 4.25. Examples of changes of the seasonal thermocline (source: [EPI]). He...
Figure 4.26. Representation of pycnocline: excess potential density based on red...
Figure 4.27. Adiabatic displacement of a fluid parcel in a hydrostatic pressure ...
Figure 4.28. Representation of the vertical temperature gradient for different t...
Figure 4.29. Representation of flow patterns close to horizontal non-divergence ...
Figure 4.30. Temperature profiles at 79°0’ north latitude
Figure 4.31. Examples of temperature, salinity, and density measurements, accord...
Figure 4.32. Schematic representation of the thermohaline circulation in four st...
Figure 4.33. Salinity profile in the Pacific Ocean along the 155.5° meridian of ...
Guide
Cover
Table of Contents
Begin Reading
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Illustration representative of the book: the Challenger expedition (route, vol. 1), physical measurements (samples, vol. 2) and the compressibility of liquids (globes, vol.3)
From Deep Sea to Laboratory 2
Discovering H.M.S. Challenger’s Physical Measurements Relating to Ocean Circulation
Frédéric Aitken
Jean-Numa Foulc
First published 2019 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd
27-37 St George’s Road
London SW19 4EU
UK
www.iste.co.uk
John Wiley & Sons, Inc.
111 River Street
Hoboken, NJ 07030
USA
www.wiley.com
Cover image © John Steven Dews (b.1949), H.M.S. Challenger in Royal Sound, Kerguelen Island, in the Southern Ocean (oil on canvas).
© ISTE Ltd 2019
The rights of Frédéric Aitken and Jean-Numa Foulc to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.
Library of Congress Control Number: 2018965669
British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-78630-375-2
Foreword
It is a beautiful adventure that Frédéric Aitken and Jean-Numa Foulc have undertaken, using physical data from the Challenger expedition, the first major oceanographic expedition, sponsored by the British Admiralty in the 1870s. Indeed, this data, temperature and pressure readings at various depths and at multiple points of the world, was relatively little used at the time despite the visionary intuition of one of the initiators of the expedition, Professor Carpenter, that this data would allow for the reconstruction of ocean circulation. The authors attribute this relative lack of interest to the fact that most scientists on the expedition were naturalists, and that from the point of view of biology, the total benefits were already huge, with, for example, the discovery of life at a great depth.
Exploiting data is not the least interesting of the physicist’s tasks. To deal with the problem, we simplify the situation and try not to delete anything essential. The terms of the equations are evaluated, keeping only the most important, and then two situations may arise. Let us say that the discrepancy with the data is clear: we are generally convinced that it has been oversimplified, but where? We are tempted in bad faith to defend our idea, even if it means becoming the Devil’s advocate and destroying what we have built. We go back to the overlooked terms one by one, and, with some luck, this may lead to a new effect. We make do with what we know; the battle is tough, and this is its appeal.
Let us say that the similarity is acceptable. This is when a good physicist is suspicious: is it not a coincidence that two important effects are not offset by any chance? It would be necessary to make a prediction, and to repeat the experiment in different conditions, but it is not always possible. Another boat was not sent out with 200 people around the world for three years! The rigor with which experiments have been conducted, and the confidence that can be placed in the measures, are essential. The experimenters have had to multiply the situations blindly, without knowing which ones would be used as a test, with the sole aim of doing their best every time, by describing their protocol for future use.
The development of the measurement protocol is part of the experiment’s design, as was instrument construction. At that time, a physicist worth his salt would never have used an instrument that he did not know how to build. How can one measure a temperature in a place that one cannot reach oneself (2,000 m below the surface of the sea, for example)? We can record the maximum and minimum temperatures reached during the descent (I found, with much emotion, the description of the maximum and minimum thermometer used by my grandfather in his garden). But what to do for intermediate temperatures? How to make sure that the line does not break in bad weather under the boat’s blows? How to decide the real depth despite currents, and the fact that the line continues to run under its own weight once the sensor is at the bottom? The design phase of the experiment can be exciting: I knew a physicist who was ready to sabotage a barely built experience (under the pretext, of course, of improving it) to be able to move more quickly to the design of the following experiment.
Despite all the attention given to the design, sometimes an error is suspected in the measurements. This is the case here. Having reached unexpected depths (they discovered the Mariana Trench), the Challenger scientists wondered if their measurements had not been distorted by contraction of the glass envelopes. After their return, they assigned Peter Tait, a physicist from Edinburgh, the task of assessing these errors. One thing leading to another, he raised questions about the compressibility of seawater, and other liquids, and so about their equation-of-state, connecting pressure, temperature and density (and even salinity). The result of his studies left a lasting mark on the physics of liquids. Estimating errors, a task hated and despised by the typical physics student, yielded new knowledge.
From the same period as the van der Waals equation, Tait’s efforts were part of the first trials to represent the equation-of-state of dense, liquid and solid bodies by continuous functions. The goal was twofold: metrological, to interpolate between experimental results, and to provide experimenters and engineers with the most accurate characterization of the thermodynamic and physical properties of the fluids they use. But also more fundamental, in the wish to have a better understanding of the underlying physical mechanisms: formation of molecular aggregates, local crystalline order, shape of interaction potentials, etc. These two interests, pragmatism and rigor, are often in conflict, as is clear from the authors’ account, who apply the ideas from that time to fluids that were not of concern then, such as the fluid phases of the two stable isotopes of helium.
Many aspects of this scientific adventure are thus universal, and it is touching to see how the value codes of the scientific approach have been transmitted over decades, or almost centuries. But our step back in time gives us an advantage: the ability to judge the ideas from that period in light of the extraordinary sum of knowledge that has been accumulated since. However, a direct comparison would be unfair and clumsy. It is much more interesting to put us in the mindset of the players of that era, to share their doubts, their hesitations and even their mistakes. This is an aspect that is too often absent from our education. For the sake of efficiency, we do not mention brilliant ideas that have led to a stalemate. Yet these ideas may contribute elsewhere. There may be some hesitation in mentioning great names such as Clausius, Joule and van der Waals, who fill us not only with humility in the face of the mastery that allowed them to find the right path, but also with confidence when faced with our own doubts. The variety of players and points of view that have marked this period show how much science is a collective adventure.
It is all of this that I found in this book by Frédéric Aitken and Jean-Numa Foulc, and even more: the human adventure that was this trip of three years around the world, the incidents, drama and joys, what it revealed about the personality of each participant, their lives which, for some, are also described, the moving relay that is transmitted when a change of assignment, or worse, death, interrupts a task. There is also the welcome reserved for the expedition, sometimes idyllic (ah! the difficulty of leaving Tahiti), sometimes colder, the importance of the band and personal talent of the participants, not to mention the providence that the Challenger represented for the Robinsons, abandoned on an island by a boat that was unable to come back for them. After reading the story based on the logbook, how can we not mention Jules Verne’s novels? It is the same period, that of a thirst for knowledge about our environment, accessible to all of us, acquired by real yet so human adventurers, so close to us. The credit goes to the authors for having dedicated so much time, energy and enthusiasm to this humanist and complete book, with the spirit of this laboratory where I had the pleasure to come for discussions during my years at Grenoble.
Bernard CASTAING Member of the French Academy of Sciences
Preface
In May 1876, the oceanographic expedition of the H.M.S. Challenger reached England after having sailed the seas of the world for more than three years. The main objectives of this expedition were to study animal life in depth, examine the ocean floor in order to improve knowledge of undersea reliefs and observe the physical properties of the deep sea in order to establish the link between ocean temperatures and currents. This point was suggested by the naturalist William Carpenter, one of the promoters of the Challenger expedition. However, although work on animal life was widely promoted after the expedition, the same was not true of the physical observations accumulated throughout the expedition because the theoretical knowledge of ocean dynamics was almost non-existent back then.
Yet as early as 1870, one of the initiators of the Challenger expedition, naturalist William Carpenter, had suggested that ocean circulation could be reconstructed from depth-dependent water temperature profiles. One of the challenges of the book is to precisely show that measurements collected by the Challenger’s scientists were the potential source of all data necessary to establish the link between currents and ocean temperatures.
Another person played a decisive role after the return of the Challenger. It was the physicist Peter Tait, who was asked by the scientific leader of the expedition to solve a tricky question about evaluating the temperature measurement error caused by the high pressure to which the thermometers were subjected. On this occasion, Tait used a new high-pressure cell that allowed him to accurately determine the correction to be made to the temperatures collected by the Challenger. Later, he embarked on more fundamental research on the compressibility of liquids and solids that led him, nine years later, to formulate his famous equation-of-state. Analysis of the properties of the compressibility of liquids is the second challenge of this book.
From Deep Sea to Laboratory has three volumes. The first volume relates the H.M.S. Challenger expedition and addresses the issue of deep-sea measurement. The second and third volumes offer a more scientific presentation that develops the two points raised earlier: the correlation between the distribution of temperature and ocean currents (Volume 2) and the properties of compressibility of seawater and, more generally, that of liquids (Volume 3).
Presentation of Volume 2
Chapter 1 begins with a history of ocean temperature measurement techniques and provides some details on the Miller–Casella thermometers used in the Challenger expedition. The second point concerns temperature measurement errors due to the high pressures encountered in the abyss. The origin of these errors and the first conclusions of Peter Tait’s works to correct the errors are presented.
Chapter 2 highlights the link between the temperature distribution and the ocean circulation. After a brief description of the stratification of the ocean in several layers, the basic elements leading to the modeling of internal geostrophic flow are recalled. The chapter continues with a more general presentation of the effect of latitude on planetary vorticity and on the transport of water masses given by the Sverdrup relation.
Chapter 3 develops a simplified modeling of the thermocline, taking into account only thermal and mechanical aspects. The thermocline resolution (e.g. expressions giving the depth of the isotherm 10°C as a function of latitude and longitude) is discussed in various hypothetical cases. Temperature measurements taken during the Challenger expedition are used to determine a typical thermocline scale, average (common to all the three oceans) and symmetrical (valid for both hemispheres), as a function of latitude.
Chapter 4 provides an overview of the ocean circulation associating the interactions between the inner layer in geostrophic equilibrium and the adjacent layers: ocean mixed layer (OML, subjected to the wind), bottom boundary layer and lateral boundary layers (continental borders). Comparisons between theoretical models of the ocean circulation and thermocline, and between results from models and temperature measurements of the Challenger, are shown and discussed. This chapter continues by considering seasonal effects on thermocline fluctuation (stability of upper layers, examples of seasonal thermoclines) and by examining the temperature distribution in polar regions (absence of thermocline, the effect of sea ice). It ends with a presentation of the global ocean circulation, taking into account local fluctuations in temperature and salinity (thermohaline circulation).
Overview of Volumes 1 and 3
Volume 1 presents the context, organization and conduct of the expedition of the H.M.S. Challenger. The detailed account of the cruise is embellished with numerous illustrations (maps, photographs, etc.) that are rarely presented together. The key role of the officers and scientists involved in this cruise is highlighted, and a brief biography of each of them is presented. In the first volume, we also discuss the problem of deep-sea sounding, which at the time was a delicate and not always well-controlled operation. A theoretical approach to the immersion velocity of a lead is given and compared to the experiment. We end with a presentation of some results of bathymetric surveys and physical observations made by the Challenger’s scientists. Bathymetric surveys are used to represent typical and known seabed reliefs (e.g. the Mariana Trench, South Atlantic ridges, etc.), and physical observations appear in the form of temperatures, salinities and densities depending on the depth.
Volume 3 begins with a reminder of the concept of compressibility and its associated coefficients. We then present a detailed history of techniques for measuring the compressibility of liquids. This leads us naturally to Tait’s work undertaken since 1879 on the measurement of the compressibility of fresh water, seawater, mercury and glass and its equation-of-state set with two parameters. The evolutions and the physical interpretations of the parameters of the Tait equation, as well as those associated with the Tait–Tammann equation, are studied by comparison or analogy with some classical equations-of-state, especially including that of van der Waals, so as to obtain a certain image of the “structure” of liquid media. An in-depth study of the isothermal mixed modulus and the adiabatic tangent modulus leads us to propose new equations-of-state. We show that these new relationships have a precision comparable to that of reference equations and thus enable us to describe, in particular, the liquid phase of fresh water, seawater and helium-3 and -4. Different “anomalies” of these mediums are then highlighted and discussed.
The book describes a “journey over and through water” with a cross-examination of human history, the history of science and technology, terrestrial and undersea geography, ocean dynamics and thermics, and the sciences dealing with the physical properties of liquids. Curious readers, attracted by travel, science and history, will discover the background and conduct of a great scientific expedition in Volume 1. Students, engineers, researchers and teachers of physics, fluid mechanics and oceanography will also find subjects to deepen their knowledge in Volumes 2 and 3.
We would like to warmly thank Bernard Castaing, a former professor at the Joseph Fourier University of Grenoble (France) and at the École Normale Supérieure of Lyon, France, for carefully reading the manuscript and for his pertinent remarks. We express our gratitude to Ferdinand Volino and André Denat, Senior Researchers at the CNRS, and Jacques Bossy, CNRS researcher, who kindly shared their observations and advice during the preparation of the manuscript and read the final manuscript. We warmly thank Armelle Michetti, head of the library of physics laboratories of the CNRS campus in Grenoble, for her contribution to the search for often old and restricted documents that enabled us to illustrate and support the historical and scientific parts of the book.
We also thank the people who gave us special support: Michel Aitken, Philippe Vincent, Yonghua Huang, Glenn M. Stein and J. Steven Dews.
Finally, we would like to thank the organizations and their staff who have graciously allowed us to use some of their iconographic holdings, and in particular the Natural History Museum in London, the National Portrait Gallery in London, the United Kingdom Hydrographic Office in London, the University of Vienna (Austria), the scientific museum of the Lycée Louis-le-Grand in Paris and Orange/DGCI Company.
Bibliographical references on specific points appear in footnotes, and those of a more general nature are collated in the references section at the end of each volume. The footnote reference numbers always correspond to footnotes of that chapter.
Frédéric AITKEN Jean-Numa FOULC March 2019
1The Vertical Distribution of Temperature in the Ocean
Thermometer readings
(source: [THO 85])
1.1. Introduction
In Volume 1 of the book, we explained the reasons that led the British government to organize a large-scale scientific expedition across the oceans. After the H.M.S. Challenger was completely refurbished, this former military ship was converted into a floating laboratory. From then on, the scientists and officers assigned to this expedition, which went on from December 1872 to May 1876, were entrusted with two main missions: to study animal life in depth, and observe the ocean waters and the ocean floor. Volume 2 concerns the second mission. This part of the book focuses on the relationship between the ocean circulation and the distribution of temperature in the ocean.
As early as the mid-19th Century, Matthew Maury1, an officer of the US Navy who was considered the pioneer of hydrography and marine meteorology, proposed a theory to explain the general ocean circulation (Figure 1.1). Taking the example of the North Atlantic, M. Maury suggested that the main cause of currents was the difference in the density of seawater in the tropical region (high salinity water) and in the polar region (low salinity water). This difference in density of the water creates a surface current, in the direction of the North Pole, then a vertical current towards the bottom, and finally a counter-current in the depths, in the direction of the equator [MAU 05]. There was no unanimity on this first theory on the dynamics of the water masses and it was criticized by many physicists who found it implausible [REC 74]. In the early 1870s, the British naturalist W.B. Carpenter (see Volume 1, section 2.3), one of the initiators of the cruise of the H.M.S. Challenger
