Environmental Fluid Mechanics – serie

This book grew out of lectures on geophysical fluid dynamics delivered over many years at the Moscow Institute of Physics and Technology by the author (and, with regard to some parts of the book, by his colleagues). During these lectures the students were advised to read many books, and sometimes individual articles, in order to acquaint themselves with the necessary material, since there was no single book available which provided a sufficiently complete and systematic account (except, perhaps, the volumes on Hydrophysics of the Ocean, Hydrodynamics of the Ocean, and Geodynamics in the ten-volume Oceanology series published by Nauka Press in 1978-1979; these refer, however, specifically to the ocean, and anyway they are much too massive to be convenient for study by students). As far as we know, no text corresponding to our understanding of geophysical fluid dynamics has as yet been published outside the Soviet Union. The present book is designed to fill this gap. Since it is customary to write the preface after the entire book has been completed, the author has an opportunity there to raise some points of possible criticism by the reviewers and readers. First of all, note that this work presents the theoretical fundamentals of geophysical fluid dynamics, and that observational and experimental data (which in the natural sciences are always very copious) are referred to only rarely and briefly.

The phenomenon of evaporation in the natural environment is of interest in various diverse disciplines. This book is an attempt to present a coherent and organized introduction to theoretical concepts and relationships useful in analyzing this phe­ nomenon, and to give an outline of their history and their application. The main objective is to provide a better understanding of evaporation, and to connect some of the approaches and paradigms, that have been developed in different disciplines concerned with this phenomenon. The book is intended for professional scientists and engineers, who are active in hydrology, meteorology, agronomy, oceanography, climatology and related environ­ mental fields, and who wish to study prevailing concepts on evaporation. At the same time, I hope that the book will be useful to workers in fluid dynamics, who want to become acquainted with applications to an important and interesting natural phenomenon. As suggested in its subtitle, the book consists of three major parts. The first, consisting of Chapters I and 2, gives a general ouline of the problem and a history of the theories of evaporation from ancient times through the end of the nineteenth century. This history is far from exhaustive, but it sket~hes the background and the ideas that led directly to the scientific revolution in Europe and, ultimately, to our present-day knowledge.

For some time there has existed an extensive theoretical literature relating to tides on continental shelves and also to the behavior of estuaries. Much less attention was traditionally paid to the dynamics of longer term, larger scale motions (those which are usually described as circulation') over continental shelves or in enclosed shallow seas such as the North American Great Lakes. This is no longer the case: spurred on by other disciplines, notably biological oceanography, and by public concern with the environment, the physical science of the coastal ocean has made giant strides during the last two decades or so. Today, it is probably fair to say that coastal ocean physics has come of age as a deduc­ tive quantitative science. A well developed body of theoretical models exist, based on the equations of fluid motion, which have been related to observed currents, sea level variations, water properties, etc. Quantitative parameters required in using the models to predict e.g. the effects of wind or of freshwater influx on coastal currents can be estimated within reasonable bounds of error. While much remains to be learned, and many exciting discoveries presumably await us in the future, the time seems appropriate to summarize those aspects of coastal ocean dynamics relevant to 'circulation' or long­ term motion.

Four years have elapsed since the preparation of the original Russian version of this book. This is a long time when dealing with such actively expanding fields of oceanography as research into small-scale structures and the investigation of hydro physical processes. Over this period new quick-response devices have been developed and successfully used for measurements taken in various ocean areas. Improvements in high-frequency meters used to measure hydrophysical parameters has enabled workers to obtain more accurate absolute values of the fluctuations measured by such devices. In view of this scientific progress, some of the ideas presented in this book now require additional explanation. Great care should be used in dealing with the absolute fluctuation values of hydro physical fields, since the methods used for the determination of the accuracy of the high-frequency measuring devices have been imperfect in the past. Never­ theless, it would appear that the results of the investigations summarized in this book have not lost their importance, and that the established laws governing small-scale pro­ cesses in the ocean are of a sufficiently universal nature and, as such, have not been shattered with the qualitative and quantitative advances in devices used for measurements taken in oceans. The authors feel that their work is of interest to English-speaking readers. The appearance of the English translation of the book is, to a very large extent, due to the tremendous amount of editing work brilliantly done by Prof. H. Tennekes.

1. ABOUT THE DISCIPLINE 'DYNAMIC METEOROLOGY' The name 'dynamic meteorology' is traditional for designating a university course as well as the scientific branch of meteorology as a whole. While there is no need to abandon this name, it needs contemporary treatment and specifications in its definition. A synonym for it could be 'dynamics (more precisely, hydrodynamics or fluid dynamics) of the atmosphere'. It suggests the relationship of this discipline to general hydrodynamics and applied mathematics and its pronounced theoretical nature. Besides the atmosphere, however, our planet has another (liquid) envelope - the hydrosphere (world's ocean), which also concerns ocean dynamics and, therefore, it is necessary to define, from a unified standpoint, the subject and aims of the disciplines dealing with the dynamics of the processes which take place in both fluid spheres. Such a unified standpoint offers the so-called geophysical fluid dynamics. During the past few years this description is encountered quite often in scientific literature concerning the Earth as a planet. Obviously, a scientific branch or a science is created whose subject is our planet and the investigation methods are borrowed from classical fluid dynamics and applied mathematics, including the most recent numerical methods. As can be seen from its very suitable name, it is the dynamics of quite definite geophysical fluids (atmosphere, ocean and even the liquid inside of the Earth) and not of some abstract (often perfect) flUids, as in classical hydrodynamics.

The phenomenon of evaporation in the natural environment is of interest in various diverse disciplines. This book is an attempt to present a coherent and organized introduction to theoretical concepts and relationships useful in analyzing this phe­ nomenon, and to give an outline of their history and their application. The main objective is to provide a better understanding of evaporation, and to connect some of the approaches and paradigms, that have been developed in different disciplines concerned with this phenomenon. The book is intended for professional scientists and engineers, who are active in hydrology, meteorology, agronomy, oceanography, climatology and related environ­ mental fields, and who wish to study prevailing concepts on evaporation. At the same time, I hope that the book will be useful to workers in fluid dynamics, who want to become acquainted with applications to an important and interesting natural phenomenon. As suggested in its subtitle, the book consists of three major parts. The first, consisting of Chapters I and 2, gives a general ouline of the problem and a history of the theories of evaporation from ancient times through the end of the nineteenth century. This history is far from exhaustive, but it sket~hes the background and the ideas that led directly to the scientific revolution in Europe and, ultimately, to our present-day knowledge.

For some time there has existed an extensive theoretical literature relating to tides on continental shelves and also to the behavior of estuaries. Much less attention was traditionally paid to the dynamics of longer term, larger scale motions (those which are usually described as circulation') over continental shelves or in enclosed shallow seas such as the North American Great Lakes. This is no longer the case: spurred on by other disciplines, notably biological oceanography, and by public concern with the environment, the physical science of the coastal ocean has made giant strides during the last two decades or so. Today, it is probably fair to say that coastal ocean physics has come of age as a deduc­ tive quantitative science. A well developed body of theoretical models exist, based on the equations of fluid motion, which have been related to observed currents, sea level variations, water properties, etc. Quantitative parameters required in using the models to predict e.g. the effects of wind or of freshwater influx on coastal currents can be estimated within reasonable bounds of error. While much remains to be learned, and many exciting discoveries presumably await us in the future, the time seems appropriate to summarize those aspects of coastal ocean dynamics relevant to 'circulation' or long­ term motion.

During the Conference on Air-Sea Interaction in January 1986, it was suggested to me by David Larner of Reidel Press that it may be timely for an updated compendium of air-sea interaction theory to be organized, developed, and published. Many new results were emerging at the time, i.e., results from the MARSEN, MAS EX, MILDEX, and TOWARD field projects (among others) were in the process of being reported and/or published. Further, a series of new experiments such as FASINEX and HEXOS were soon to be conducted in which new strides in our knowledge of air-sea fluxes would be made. During the year following the discussions with David Larner, it became apparent that many of the advances in air-sea interaction theory during the 1970s and 1980s were associated with sponsor investments in satellite oceanography and, in particular, remote sensing research. Since ocean surface remote sensing, e.g., scatterometry and SAR, requires intimate knowledge of ocean surface dynamics, advances in remote sensing capabilities required coordinated research in air-sea fluxes, wave state, scattering theory, sensor design, and data exploitation using environmental models. Based on this interplay of disciplines, it was decided that this book be devoted to air­ sea interaction and remote sensing as multi-disciplinary activities.

This book grew out of lectures on geophysical fluid dynamics delivered over many years at the Moscow Institute of Physics and Technology by the author (and, with regard to some parts of the book, by his colleagues). During these lectures the students were advised to read many books, and sometimes individual articles, in order to acquaint themselves with the necessary material, since there was no single book available which provided a sufficiently complete and systematic account (except, perhaps, the volumes on Hydrophysics of the Ocean, Hydrodynamics of the Ocean, and Geodynamics in the ten-volume Oceanology series published by Nauka Press in 1978-1979; these refer, however, specifically to the ocean, and anyway they are much too massive to be convenient for study by students). As far as we know, no text corresponding to our understanding of geophysical fluid dynamics has as yet been published outside the Soviet Union. The present book is designed to fill this gap. Since it is customary to write the preface after the entire book has been completed, the author has an opportunity there to raise some points of possible criticism by the reviewers and readers. First of all, note that this work presents the theoretical fundamentals of geophysical fluid dynamics, and that observational and experimental data (which in the natural sciences are always very copious) are referred to only rarely and briefly.

During the Conference on Air-Sea Interaction in January 1986, it was suggested to me by David Larner of Reidel Press that it may be timely for an updated compendium of air-sea interaction theory to be organized, developed, and published. Many new results were emerging at the time, i.e., results from the MARSEN, MASEX, MILDEX, and TOWARD field projects (among others) were in the process of being reported and/or published. Further, a series of new experiments such as FASINEX and HEXOS were soon to be conducted in which new strides in our knowledge of air-sea fluxes would be made. During the year following the discussions with David Larner, it became apparent that many of the advances in air-sea interaction theory during the 1970s and 1980s were associated with sponsor investments in satellite oceanography and, in particular, remote sensing research. Since ocean surface remote sensing, e.g., scatterometry and SAR, requires intimate knowledge of ocean surface dynamics, advances in remote sensing capabilities required coordinated research in air-sea fluxes, wave state, scattering theory, sensor design, and data exploitation using environmental models. Based on this interplay of disciplines, it was decided that this book be devoted to air­ sea interaction and remote sensing as multi-disciplinary activities.

Four years have elapsed since the preparation of the original Russian version of this book. This is a long time when dealing with such actively expanding fields of oceanography as research into small-scale structures and the investigation of hydro physical processes. Over this period new quick-response devices have been developed and successfully used for measurements taken in various ocean areas. Improvements in high-frequency meters used to measure hydrophysical parameters has enabled workers to obtain more accurate absolute values of the fluctuations measured by such devices. In view of this scientific progress, some of the ideas presented in this book now require additional explanation. Great care should be used in dealing with the absolute fluctuation values of hydro physical fields, since the methods used for the determination of the accuracy of the high-frequency measuring devices have been imperfect in the past. Never­ theless, it would appear that the results of the investigations summarized in this book have not lost their importance, and that the established laws governing small-scale pro­ cesses in the ocean are of a sufficiently universal nature and, as such, have not been shattered with the qualitative and quantitative advances in devices used for measurements taken in oceans. The authors feel that their work is of interest to English-speaking readers. The appearance of the English translation of the book is, to a very large extent, due to the tremendous amount of editing work brilliantly done by Prof. H. Tennekes.

1. ABOUT THE DISCIPLINE 'DYNAMIC METEOROLOGY' The name 'dynamic meteorology' is traditional for designating a university course as well as the scientific branch of meteorology as a whole. While there is no need to abandon this name, it needs contemporary treatment and specifications in its definition. A synonym for it could be 'dynamics (more precisely, hydrodynamics or fluid dynamics) of the atmosphere'. It suggests the relationship of this discipline to general hydrodynamics and applied mathematics and its pronounced theoretical nature. Besides the atmosphere, however, our planet has another (liquid) envelope - the hydrosphere (world's ocean), which also concerns ocean dynamics and, therefore, it is necessary to define, from a unified standpoint, the subject and aims of the disciplines dealing with the dynamics of the processes which take place in both fluid spheres. Such a unified standpoint offers the so-called geophysical fluid dynamics. During the past few years this description is encountered quite often in scientific literature concerning the Earth as a planet. Obviously, a scientific branch or a science is created whose subject is our planet and the investigation methods are borrowed from classical fluid dynamics and applied mathematics, including the most recent numerical methods. As can be seen from its very suitable name, it is the dynamics of quite definite geophysical fluids (atmosphere, ocean and even the liquid inside of the Earth) and not of some abstract (often perfect) flUids, as in classical hydrodynamics.

The flow of gravity currents and intrusions is a subject of active research and engineering application. Currently, there are no formal teaching courses for this topic. Materials and information available in the market are scattered and dated. Researchers and engineers face difficulties in acquiring the "state-of-the-art" knowledge. The book bridges this gap between the need and supply of the relevant insight and know-how.Written by a renowned author who is a recognized authority in the field, this unique compendium assembles the relevant knowledge into a systematic and unified framework. The presentation is gradual from the elementary to the frontier, and accessible to readers with only a basic background in fluid mechanics and applied mathematics. This will facilitate the systematic acquirement and application of available knowledge to both practical problems and further research.This must-have volume is a useful monograph — that can also serve as a textbook in advanced courses — for researchers, students, engineers and applied mathematicians in the fields of civil engineering, hydraulic engineering, mechanical engineering, ocean engineering and environmental engineering.