Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.iki.rssi.ru/asp/pub_sha6/pub_sha6.pdf Äàòà èçìåíåíèÿ: Mon Dec 17 21:36:54 2007 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 09:55:12 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ýòà êèëÿ

Eugene A. Sharkov

Breaking Ocean Waves
Geometry, Structure, and Remote Sensing

Praxis Publishing ublishing
Chichester, UK

Published in association with


Professor Eugene A. Sharkov Space Research Institute Russian Academy of Sciences Moscow Russia

SPRINGER±PRAXIS BOOKS IN GEOPHYSICAL SCIENCES SUBJECT ADVISORY EDITOR: Philippe Blondel, C.Geol., F.G.S., Ph.D., M.Sc., Senior Scientist, Department of Physics, University of Bath, Bath, UK

ISBN 978-3-540-29827-4 Springer Berlin Heidelberg New York Springer is part of Springer-Science + Business Media (springer.com) Library of Congress Control Number: 2007928830 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 of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. # Praxis Publishing Ltd, Chichester, UK, 2007 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a speci®c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: Jim Wilkie Project management: Originator Publishing Services Ltd, Gt Yarmouth, Norfolk, UK Printed on acid-free paper


Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of ®gures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of abbreviations and acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction and rationale . . . . . . . . . . . . . . . . . . . . . . . 1.1 Breaking ocean waves in the atmosphere±ocean system 1.1.1 Wave dynamics at wave breaking . . . . . . . . 1.1.2 Energy exchange at wave breaking . . . . . . . 1.1.3 Gas exchange in the ocean±atmosphere system 1.2 Breaking ocean waves and microwave remote sensing 1.3 Classi®cation of investigation techniques: methodology ments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. .. . .. of .. .. .... .... .... .... .... .... experi .... .... . . . . . . . .

xi xvii xix xxiii xxv 1 1 1 2 4 5 7 8 9 9 10 11 13

2

Spatial stochastic breaking wave ®elds in the atmosphere±ocean system . 2.1 Statement of the problem of studying the spatial stochastic structure of breaking waves . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Technique and conditions for performing ®eld experiments . . . . 2.2.1 Meteorological conditions during the experiment and the ¯ight performance technique . . . . . . . . . . . . . . . . . . 2.2.2 Technique for performing the contact part of the experiment and data processing . . . . . . . . . . . . . . . .


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Contents

2.3

2.4

2.5

2.6 3

The strati®cation state and the turbulent mode of a nearsurface layer. The ``net'' fetch conditions . . . . . . . . . . 2.2.4 Restoration of the spectral characteristics of the sea surface from its optical images . . . . . . . . . . . . . . . . . 2.2.5 Spatial±spectral structure of sea waves . . . . . . . . . . . . Spatial±statistical properties of a breaking wave ®eld in developed seas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.1 The technique of formation and processing of a randompoint ®eld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.2 Laws of speci®c density distribution . . . . . . . . . . . . . 2.3.3 Spatial homogeneity and representativeness of a breaking ®e ld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.4 Linear non-correlation of breaking ®elds . . . . . . . . . . 2.3.5 Azimuth homogeneity of breaking ®elds . . . . . . . . . . . 2.3.6 Markov's property of the breaking ®eld . . . . . . . . . . . Spatial±statistical properties of a developing sea breaking ®eld . 2.4.1 The technique of forming and processing the random point ®eld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2 Markov property of the breaking ®eld . . . . . . . . . . . . 2.4.3 Laws of speci®c density distribution . . . . . . . . . . . . . . 2.4.4 Linear non-correlation of breaking center speci®c density 2.4.5 Spatial homogeneity of breaking center speci®c density. . Fractal properties of wave-breaking zones in stationary and developing seas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1 Techniques of formation and processing of the randompoint ®eld for fractal processing . . . . . . . . . . . . . . . . 2.5.2 Fractal properties of breaking ®elds under developed sea conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.3 Fractal properties of breaking ®elds under developing sea conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.3

13 16 18 21 22 23 28 30 31 34 36 36 38 40 40 42 42 43 44 46 48 49 49 50 52 58 61 68

Linear and two-dimensional geometry of whitecapping and foam structures 3.1 The problem of studying the spatial±stochastic structure of individual breaking waves . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Remote investigation of individual foam structures in the wavebreaking process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Processing the data from remote sensing of individual foam structures in the wave-breaking process . . . . . . . . . . . . . . . . . 3.4 Statistics on the elements in the linear geometry of individual foam structures in the wave-breaking process . . . . . . . . . . . . . 3.5 Statistics of elements of the two-dimensional geometry of individual foam structures in the wave-breaking process . . . . . . . . 3.6 Statistics of the speci®c density of breaking centers . . . . . . . . .


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vii

3.7

3.8 4

A spatial ®eld of wave breakings and the overshoot theory for a random Gaussian ®eld . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.1 Properties of a ¯ux of ®xed level crossings by the Gaussian ®eld . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.2 The intensity of a ¯ux of ®xed level crossings by the Gaussian ®eld and experimental observations . . . . . . . 3.7.3 Regions of overshoots of an isotropic Gaussian ®eld and experimental observations . . . . . . . . . . . . . . . . . . . . 3.7.4 On the relationship between the dissipation and transparency intervals in spectra of sea wave heights . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. the .. .. of .. .. .. .. .. .. ... sea ... ... the ... ... ... ... ... ... . . . . . .

72 73 75 77 79 80 83 83 85 86 89 90 96 100 101 103 103 106 107 110 117 119 119 123 128 132 136 136 139 148

The life-temporal dynamics of sea wave breakings . . . . . . . . . 4.1 The problem of studying the life-temporal dynamics of wave breaking process . . . . . . . . . . . . . . . . . . . . . . . 4.2 Technique and conditions of ®eld experiments . . . . . . . 4.2.1 Optical observations of the temporal evolution breaking process . . . . . . . . . . . . . . . . . . . . . 4.2.2 Optical image processing technique . . . . . . . . . 4.3 Temporal evolution of the breaking process . . . . . . . . . 4.4 Spatiotemporal characteristics of mesobreakings . . . . . . 4.5 Spectral characteristics of an aerated layer . . . . . . . . . 4.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

The drop-spray phase over a rough sea surface . . . . . . . . . . . . . . . 5.1 Physical mechanisms of drop-spray phase generation . . . . . . . 5.2 Disperse characteristics of the drop-spray phase . . . . . . . . . . 5.2.1 Laboratory measurements of the characteristics of a drop spray phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2 Field measurements of drop-spray phase characteristics 5.3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electr 6.1 6.2 6.3 6.4 6.5

6

odynamics of a rough, disperse, closely packed media . . . . . . . . Foam as a colloidal system: physical and structural properties . Physical and chemical properties of sea foam . . . . . . . . . . . . . Disperse structure of sea foam in the Black Sea basin . . . . . . . Earlier measurements and ``naive'' electromagnetic models . . . . . Experimental investigations of characteristics of roughly disperse systems by radiophysical methods . . . . . . . . . . . . . . . . . . . . 6.5.1 Laboratory analogs of foam systems and their disperse characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.2 Spectral and polarization properties of the radiothermal radiation of disperse systems . . . . . . . . . . . . . . . . . . . 6.5.3 Re¯ective properties of disperse systems in the microwave range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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Contents

6.6

6.7

The theory of natural radiation of disperse closely packed systems 6.6.1 An inhomogeneous dielectric layer adequate for heterogeneous mixing of water and air . . . . . . . . . . . . . . . . 6.6.2 Transition and layer-inhomogeneous models . . . . . . . . 6.6.3 Electromagnetic properties of a bubble in the microwave range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6.4 Optical model of a disperse medium . . . . . . . . . . . . . 6.6.5 Diffraction models of disperse systems . . . . . . . . . . . . 6.6.6 Layered, inhomogeneous diffraction model . . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

154 154 156 157 165 169 173 177

7

Electrodynamics of concentrated drop ¯ows . . . . . . . . . . . . . . . . . . 7.1 Electromagnetic properties of secluded particles . . . . . . . . . . . . 7.1.1 The scattering cross-section and scattering amplitude . . 7.1.2 The absorption cross-section . . . . . . . . . . . . . . . . . . 7.1.3 The extinction cross-section . . . . . . . . . . . . . . . . . . . 7.1.4 Single-scattering albedo . . . . . . . . . . . . . . . . . . . . . . 7.1.5 The scattering indicatrix . . . . . . . . . . . . . . . . . . . . . 7.2. Basic concepts of the Mie theory . . . . . . . . . . . . . . . . . . . . . 7.2.1 Parameters of the Mie theory . . . . . . . . . . . . . . . . . . 7.2.2 The main results of the Mie theory . . . . . . . . . . . . . . 7.2.3 The three regions of Mie scattering . . . . . . . . . . . . . . 7.3 Scattering properties of aqueous particles . . . . . . . . . . . . . . . 7.4 Electromagnetic properties of polydisperse media . . . . . . . . . . 7.4.1 The density function . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2 The volume density of particles . . . . . . . . . . . . . . . . 7.4.3 The integral distribution function . . . . . . . . . . . . . . . 7.4.4 The relative density function . . . . . . . . . . . . . . . . . . 7.4.5 The density sampling probability . . . . . . . . . . . . . . . 7.4.6 The total mass and the relative volume concentration of water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.7 Radar re¯ectivity . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.8 Rainfall rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.9 Analytical forms of the density function . . . . . . . . . . . 7.4.10 Parameters of attenuation and scattering of a polydisperse medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 Backscattering by natural polydisperse volume targets . . . . . . . 7.6 Features of radiative transfer in dense media . . . . . . . . . . . . . 7.6.1 A disperse medium and its characteristics . . . . . . . . . . 7.6.2 Experimental technique and instruments . . . . . . . . . . . 7.6.3 Average values of electrodynamical characteristics . . . . 7.6.4 Fluctuation mode of extinction . . . . . . . . . . . . . . . . . 7.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

179 179 180 182 182 183 183 184 185 186 188 189 194 195 195 196 196 196 197 198 198 199 200 204 209 210 211 213 215 221


Contents ix

8

Field optical±microwave remote sensing of the air±sea transition zone in the atmosphere±ocean system . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Space oceanography problems . . . . . . . . . . . . . . . . . . . . . . . 8.2 Optical and radiophysical investigations of the oceanic gravity wave breaking process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Instruments, techniques, and conditions for performance of the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2 Experimental investigations of natural breaking . . . . . . 8.2.3 Experimental investigation of the breaking of ship waves 8.2.4 Interpretation of results: the drop-spray model and a ``radioportrait'' of a breaking sea wave . . . . . . . . . . . 8.3 Radio emission of crest and strip foam: ®eld ship investigations 8.4 Radio emission of a breaking wave ®eld: airplane investigations 8.5 Nonlinear dynamics of gravity waves in the breaking wave backscattering ®eld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.1 Experimental region and wind±wave conditions . . . . . . 8.5.2 Radar measurement technique . . . . . . . . . . . . . . . . . 8.5.3 Analysis of spatiotemporal diagrams . . . . . . . . . . . . . 8.5.4 Analysis of spatial frequency spectra . . . . . . . . . . . . . 8.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

223 223 227 227 228 235 237 241 246 251 253 253 255 257 261 263 265 277

9

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Preface

The surface of the ocean has drawn the most intent attention of human beings from the very beginning of mankind's history. The breaking of large oceanic waves has an especially hypnotic eect on any ordinary man or woman observing this magni®cent phenomenon. These natural processes have repeatedly been the themes in painting (see Plate 1), literature, and music. Very fewïif anyïpeople have remained indifferent to this manifestation of the greatness of nature. No less important are the oceanic wave breaking processes for scienti®c concepts and views in the study of the World Ocean as well. The study of the physical and dynamic characteristics of gravity waves on the sea surface while they break and the subsequent foam activity and formation of dropspray clouds are amongst the major problems facing modern satellite oceanology, physics of the ocean±atmosphere interaction, and oceanic engineering (see Plate 2). In particular, the contribution of foam and drop-spray systems of various types to mean values and spatiotemporal variations in microwave (radio emission and backscattering), infrared, and optical parameters of a rough sea surface is signi®cant. Knowledge of the detailed statistical characteristics of breaking wave ®elds is also important in the study of the dynamics of sea waves (generation of waves, nonlinear interactions, dissipation, etc.). Despite the external accessibility and seeming simplicity of visual and instrumental observation of the oceanic wave breaking process, detailed scienti®c data on spatial breaking ®elds in many dierent areas of the World Ocean obtained in ®eld remote-sensing experiments are still not yet available. This is principally due to the high spatiotemporal variability in the process of breaking gravity oceanic waves under rough sea conditions and high values of wind speeds over the oceanic surface. Under such complicated aerial navigation conditions, there arise both ®eld experimental methodological complications in remote sensing of these rapid processes by ships and airplanes, and complications of administrative character (e.g., banning of air ¯ights under complex meteorological conditions). And space-borne instruments still do not


xii

Preface

Plate 1. Thirty-six views of Mt. Fuji: View through waves o the coast of Kanagawa, by Katsushika Hokusai (18th century).

possess the spatial resolution sucient for remote recording of oceanic wave breaking processes. Note also thatïdepending on the scienti®c approaches and particular tasks of remote sensing and sea hydrodynamicsïthe basic characteristics of the breaking process should now be considered in two principally dierent aspects at least: in the individual aspect (i.e., in the form of a temporal set of individual breakings) and in plural representation (i.e., in the form of a spatial ®eld of breaking oceanic waves). It should further be noted thatïdepending on the geometrical characteristics of a remote-sensing system (¯ight altitude, instantaneous ®eld of view, and time constant of signal storage)ïthe contribution from the same disperse structure or from a set of structures can in principle be dierent. This book represents the ®rst detailed analytical description of the state of remote investigations (in the optical and microwave ranges of electromagnetic waves) of one of the major nonlinear elements of sea dynamics: the process of breaking gravity waves and their subsequent evolution and the dynamics of dispersed foam systems of various classes and the drop-spray phase. Issues in the methodology of multi-scale optical and microwave remote measurements are considered; and the techniques used to study individual breakings and meso-scale, discrete, breaking, random point ®elds are described. The results of ®eld investigations are presented. The advantages and


Preface

xiii

Plate 2. Oil platform in rough seas (the North Sea basin).

limitations of various remote complexes, used to reveal the spatiotemporal features of the ®elds of gravity wave breaking and disperse systems from air carriers of various classes, are also considered in the book. The latest achievements in the ®eld of electrodynamics of emission and scattering of electromagnetic waves by polydisperse close-packed polyhedral media, as well as in the ®eld of electrodynamics of dense ¯ows of the spherical particles of water, are fully described in the book. The principal feature of the book consists in an integrated description of the spatiotemporal and structural properties of breaking oceanic waves along with its electrodynamics. Emphasis is placed on the physical aspects of breaking processes necessary to judge the possibilities and limitations of remote-sensing methods in speci®c cases of oceanic surface observation. Numerous practical applications and illustrations, based on air-borne, ship-borne, and up-to-date laboratory experiments, are given in the book. The book is based on scienti®c ®ndings from several Russian scienti®c airborne remote-sensing expeditions to the Far East (the Paci®c Ocean), the Black Sea, the Caspian Sea, and the Barents Sea, as well as from several scienti®c marine expeditions to the tropics and, once more, to the Far East as part of a number of major research projects of the Russian Academy of Sciences. These ®ndings were presented in lectures by the author at the Moscow Physical and Technical Institute (in Dolgoprudnyi, near


xiv Preface

Moscow) and at the Moscow University of Geodesy, Mapping, and Aero-Photo Surveying to students of physics and geophysics. In the ®eld of application of remote observations of the oceanic surface, a book is needed that would represent a systematic and uni®ed statement of the fundamental concepts and issues of the theory of breaking gravity waves, the electrodynamic properties of disperse systems arising during the breaking process, as well as of the various instrumental and methodological issues of microwave and optical remote measurements. In addition, it would be useful to provide a uni®ed and systematic description of the latest achievements in the ®eld of microwave sensing of a rough sea surface (i.e., one that is easily accessible to undergraduate students, post-graduate students, researchers, engineers, and instrument operators). The present book was conceived to give as large a systematized idea of the possibilities and modern achievements of methods of the remote sensing of a rough sea surface as possible to a wide range of specialists and interested readers. The format of the book is constructed in such a way that the reader could acquire the necessary knowledge of the physical mechanisms of breaking gravity waves that he or she needs, in addition to the most complete information available on the modern level of development of microwave and optical remote diagnostics of a rough sea surface. The content of the present book is essentially broader than the requirements that are usually set out in a handbook for students. Much of it contains detailed information and can be used as a reference book to the many special issues of the microwave and optical remote diagnostics of the oceanic surface. The ®rst chapter of the book considers the scienti®c and applied aspects of remotely sensing the sea surface, the role and place of optical and microwave methods and instruments in the study of breaking waves, the basic concepts of the modern theory of breaking gravity waves, the possibilities of passive and active methods of microwave diagnostics of a rough sea surface. The second chapter is devoted to the results of airborne sensing of spatial ®elds of breaking sea waves in two modes: limited fetch and fully developed sea state. On the basis of experimental data, important modeling ideas are proposed for the spatial ®eld of breaking sea waves that occur as a result of the formation of Poisson's point ®eld of non-interacting centers. The third chapter presents the results of experimental investigation into the geometrical characteristics (linear and two-dimensional sizes) of the process of individual breaking gravity wave (whitecapping) and foam ®elds of various types. On the basis of experimental data, the statistical models of breaking processes are constructed. Critical analysis of existing theoretical concepts of wave breaking as a result of the threshold mechanism for a random Gaussian three-dimensional ®eld (breaking criteria, threshold mechanism restrictions, etc.) is carried out. The fourth chapter gives the results of experimental investigations into the lifetime of the disperse phase of a whitecapped gravity wave: in particular, revealing the exponential character of the temporal evolution of a whitecapping crest and patch foam structures, and detection of a speci®c group of gravity wave breaking (microbreaking). The ®fth chapter is devoted to studying the nature of formation of the disperse structure and the contribution of a drop-spray phaseïformed as a result of breakingïto the mass and moisture exchange in the ocean±atmosphere system. The sixth chapter contains a


Preface

xv

detailed analysis of the electrodynamics of absorption and emission of close-packed media of colloid-type foam. The generally colloidal, physical, and disperse properties of close-packed foam structures are considered in detail. Great attention is given in this chapter to the methods of describing the electromagnetic properties of rare®ed and close-packed disperse structures; also the results of detailed experimental investigations are presented in which two types of colloidal structures were found that essentially dier in their emissive characteristics (viz., a monolayer of multiple emulsion and a foam layer of polyhedral structure). An entire spectrum of electromagnetic models of foam systems is analyzed in the chapter, and a model is found that agrees well with experimental dataïnamely, a model of the inhomogeneous dielectric layer that involves the scattering of hollow spheres and a non-sharp transitional phase boundary. The seventh chapter is devoted to studying the electrodynamics of a dropspray phase as a ¯ow of highly concentrated drop medium. Optical models for rare®ed ¯ows in the radiative transfer theory and their restrictions are considered. Then, the results of specialized experiments on studying the electromagnetic properties of dense drop ¯ows and the possibilities of their use for forming the electromagnetic models of a drop-spray phase of breaking waves are analyzed in detail. Chapter 8 is devoted to detailed analysis of remote ®eld investigations of the transition zone in the ocean± atmosphere system by means of optical, IR, and microwave air±space missions, beginning with the ®rst successful Russian missions on the ``Cosmos-243'' and ``Cosmos-384'' satellites carrying microwave multi-frequency instruments. The results of ®eld experiments carried out onboard research vessels by means of microwave active±passive instruments in the Indian Ocean are outlined in detail. Prominence is given in this chapter to the description of modern models of the state of the ocean± atmosphere system under storm conditions (models, hypotheses, preliminary experiments, etc.). The modern situation in the instrument ®eld of potential microwave remote missions, the ways of developing observation techniques and methods, and the exploiting of new frequency ranges for detailed studying of the state of the oceanic surface are all fully considered. A detailed bibliography is given at the end of the book that should be useful both for undergraduate students and post-graduate students of applicable specialties, as well as for researchers. The book is aimed at researchers, university teachers, and undergraduate and postgraduate students working in geography, meteorology, climatology, atmospheric physics, geophysics, oceanography, and in the environmental science areas of remote sensing and geophysics. Many of the experimental and full-scale results, used in preparing the book, were obtained by the author during his work at the Space Research Institute of the Russian Academy of Sciences (SRI RAS). The full-scale laboratory experiments performed during 1974±1993 by SRI co-workers using highly sensitive optical and microwave instruments, as well as the unique results obtained with their help, have determined in many respects the design of future air±space microwave instruments for studying the state of the oceanic surface.


Acknowledgments

The author is grateful to his colleagues, without whose support the unique full-scale laboratory experiments given in this book could not have been ful®lled. He especially thanks I. V. Pokrovskaya, M. D. Raev, V. M. Veselov, I. V. Chernyi, and V. Yu. Raizer. The author is thankful to Yu. Preobrazhenskii for his constructive approach to translating the manuscript into English. The typing by Nataly Komarova of such a complex manuscript is appreciated. The author also wishes to express his thanks, for support and encouragement received, to Clive Horwood of Praxis. The author also wants to acknowledge the advice and recommendations of his colleagues during preparation of the manuscript. Fully realizing the complexity and responsibility of the present publishing project, the author would like to thank readers in advance for any constructive criticism and remarks (email: easharkov@iki.rssi.ru).


Figures

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17

Thirty-six views of Mt. Fuji: View through waves o the coast of Kanagawa Oil platform in rough seas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The near-surface synoptic situation over the Caspian Sea on October 31, 1981 The schematic superposition of observing data by visual observation and by aerial photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The experimental dependence of nondimensional frequency for maximum sea wave spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . One-dimensional spectra of sea surface displacement using in situ and optical measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sections along and across the main direction of two-dimensional spatial spectra Aerial photography frame d4319 of instrument F-6 on October 31, 1981 involves a random ®eld of breaking centers . . . . . . . . . . . . . . . . . . . . . . . . Experimental histograms of foam structure densities and theoretical distributions within spatial windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental histograms of breaking wave densities . . . . . . . . . . . . . . . . . . Experimental spatial dependences of the surface density distribution function Aerial photography frame d4318 of instrument F-6 on October 31, 1981 involves the schematic sketch of the wave system and the random ®eld of breaking centers (points) in the upper inset of the . . . . . . . . . . . . . . . . . . . Experimental density distributions of breaking centers as a function of observation sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental histograms of the distribution in frequency of ``waiting area'' SW in linear and semi-logarithmic scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aerial photography frames with a random ®eld of breaking centers . . . . . . . Experimental histograms of the distribution in frequency of waiting areas with fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental density distributions of breaking centers as a function of fetch Cell structure of sea breaking ®elds for the same basin in fully developed state Dependence of the number of shaded NB and empty NS cells as a function of the linear dimension of the "K pixel in fully developed seas . . . . . . . . . . . . . . .

xii xiii 11 12 15 19 20 22 25 27 29 ?? ?? ?? 38 39 41 43 45


xx 2.18 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.1 5.2 5.3 5.4 6.1 6.2 6.3 6.4 6.5 6.6 6.7

Figures Dependence of the number of shaded NB and empty NS cells as a function of the linear dimension of the aK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air survey experimental images of a disturbed sea surface . . . . . . . . . . . . . . Experimental histograms of the distribution in frequency of maximum sizes of individual foam structures for two types . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental histogram of the distribution in frequency of minimum axis for whitecap crests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dependence of the average values for minimum and maximum dimensions . Experimental histogram of the distribution in frequency of relative foam coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dependence of the average values for relative foam coverage . . . . . . . . . . . Experimental histogram of the distribution in frequency of coverage areas of invividual structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dependence of average values for coverage areas of individual structures . . . Experimental histograms of fractional breaking event number . . . . . . . . . . . Comparison of the experimental histogram with a theoretical prediction based on the Poisson distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Side-looking radar image of a disturbed sea surface . . . . . . . . . . . . . . . . . . Typical ship-borne view of the wave-breaking process . . . . . . . . . . . . . . . . Time series of the cycle of separate waves as they break . . . . . . . . . . . . . . . Time series of dissipation of residual foam ®elds . . . . . . . . . . . . . . . . . . . . Dependence of the half-life dissipation time constants of residual foam ®elds on surface wind velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wind dependences of the area and linear size of separate samplings of whitecapping foam and mesobreakings . . . . . . . . . . . . . . . . . . . . . . . . . . . Wind dependence of the eccentricity and the maximum and minimum linear size of separate samplings of residual foam ®elds and mesobreakings . . . . . . . . . Distribution histograms of maximal sizes of separate mesobreaking-type random events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution histograms of air bubble diameters in the breaking zone . . . . . Experimental level pro®les of droplet cloud water contents during light and strong winds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental droplet distributions of spray clouds at wave breaking in surf and in rain precipitation from warm clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental droplet distributions of spray clouds . . . . . . . . . . . . . . . . . . . The dependence of water content for spray clouds at the 13-cm level above the sea surface as a function of wind velocity . . . . . . . . . . . . . . . . . . . . . . . . . Scaled model optical images of a dispersive foam medium, performed using microphotography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aerial photograph of a disturbed sea surface under a shimmering sun . . . . . The coastal zone of the northeast seaboard of Japan at the advent of stable foam mass after passage of a severe local storm . . . . . . . . . . . . . . . . . . . . . . . . . Sea surface photographs with foam structures . . . . . . . . . . . . . . . . . . . . . . Experimental probability density histogams of bubble dimensions . . . . . . . . Approximation of the normalized probability density function of the bubble dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental probability density histograms of bubble dimensions for an emulsion monolayer test specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

46 52 56 58 58 61 62 65 66 69 72 88 90 91 92 94 96 97 98 100 113 113 114 115 124 126 127 130 132 134 137


Figures xxi 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 6.22 6.23 6.24 6.25 6.26 6.27 6.28 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Experimental pro®les of water content in the polydispersive structure of an inhomogeneous layer that includes emulsion and tracery foam . . . . . . . . . . General view of experimental instruments for laboratory multi-channel radiothermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General view of the experimental area installed on the roof of a tall building at the Space Research Institute (Moscow) . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental synchronous signal registrations during the temporal decay of tracery foam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental signal registrations during the temporal decay of tracery foam Experimental synchronous signal registrations during the temporal decay of tracery foam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental spectral increment in emissivity of a water±foam structure at the expense of the dispersive layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental and theoretical emissivity dependences of the foam±water system Skeleton diagram for bistatic scatterometric measurements . . . . . . . . . . . . . Experimental scattering diagrams in the forward re¯ection regime for two foam structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spectral dependences of foam structure emissivity for a model of the inhomogeneous dielectric layer on parameters being in agreement with the heterogeneous mixture of air and water . . . . . . . . . . . . . . . . . . . . . . . . . . . Theoretical spectral dependences of foam structure emissivity . . . . . . . . . . . Theoretical dependences of the eciency factors of extinction and absoption for individual hollow water spheres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Theoretical dependences of the eciency factors of extinction, scattering, and absorption for individual water drops and hollow water spheres . . . . . . . . . Theoretical dependences of the eciency factors of extinction, scattering, and absorption for individual hollow water spheres as a function of external particle radius . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Theoretical dependences of the eciency factors of extinction, scattering, and absorption for individual hollow water spheres as a function of the thickness of an envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spectral dependences of foam structure emissivity for an optical model . . . . Theoretical spectral dependence of eective dielectric permittivity (real and imaginary parts) for the dipole interaction model . . . . . . . . . . . . . . . . . . . . Theoretical spectral dependence of the eective dielectric permittivity (real part) for the Hulst model as a function of hollow particle size . . . . . . . . . . . . . . . Schematic models of vertical pro®les for eective dielectric permittivity (real part) of dispersive structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spectral dependences of foam structure emissivity for various models . . . . . The backscattering eciency factor of a metal sphere as a function of the size parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The eciency factors of scattering, backscattering, and extinction as a function of the size parameter for aqueous spheres . . . . . . . . . . . . . . . . . . . . . . . . . Single-scattering albedo of aqueous spheres as a function of size parameter . The extinction factor of spherical raindrops as a function of frequency . . . . The spectral dependences of the eciency factors of absorption and scattering Frequency characteristics of rain attenuation . . . . . . . . . . . . . . . . . . . . . . . Frequency characteristics of attenuation for natural disperse media . . . . . . .

138 140 141 143 145 145 147 148 149 151 153 157 159 160 162 167 168 172 173 174 176 189 190 191 192 193 202 203


xxii 7.8 7.9 7.10 7.11 7.12 7.13 7.14 7.15 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19

Figures Frequency characteristics of attenuation per length unit with respect to the water content of drop-spray clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Photographs of a disperse water drop medium . . . . . . . . . . . . . . . . . . . . . . Experimental histograms of droplet radii . . . . . . . . . . . . . . . . . . . . . . . . . . The extinction coecient, radiobrightness temperature, and backscattering cross-section of disperse water drop media. . . . . . . . . . . . . . . . . . . . . . . . . Photographic registration of a signal transmitted through a water drop medium Statistical characteristics of the radiation intensity of a signal transmitted through a water drop medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The structure function of intensity ¯uctuations for a signal transmitted through a water drop medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Normalized Doppler spectra of the backscattering signal from a disperse medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Side-looking radar survey experimental pictures of a disturbed sea surface in the Paci®c basin near the Kamchatka Peninsula . . . . . . . . . . . . . . . . . . . . . . . The temporal diagram of the scatterometer and radiothermal channels recovered during observation of sea state surface . . . . . . . . . . . . . . . . . . . . A motion picture sequence of the breaking process for the gravitational wave under study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The temporal diagram of the scatterometer and radiothermal channels recovered in the gravity wave breaking process with HH polarization . . . . . Evolution temporal diagram of Doppler spectra recovered in the gravity wave breaking process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A photograph of a ship wave breaking in a 1-point (Beaufort Scale) sea state The temporal registrogram of the scatterometer and radiothermal channels used in four ship wave breakings with VV polarization . . . . . . . . . . . . . . . . A temporal diagram of the evolution of Doppler spectra recovered in the ship wave breaking process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placement of the gyroscope stabilization platform with its highly sensitive radio-thermal instruments aboard the RV Mikhail Lomonosov. . . . . . . . . . . The simultaneous radiothermal signal registrations for the breaking and foamgeneration processes at the 2.08 and 8-cm wavelengths . . . . . . . . . . . . . . . . Photographs of sea foam surface sections . . . . . . . . . . . . . . . . . . . . . . . . . Spectral characteristics of the structure of foam using various experiment data Fragment of the output signal of an airborne high-performance radiometer versus ¯ight distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The ®rst experimental results of ¯ight investigations to make detection of the azimuthal anisotropy eect in sea surface microwave emission possible . . . . The experimental results of ¯ight investigations for the azimuthal anisotropy study on sea surface microwave emission and backscattering . . . . . . . . . . . . Sea measurement area and the layout used to view the sea surface during the coastal remote-sensing study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Time±distance 2D images of the radar backscattering signal from a disturbed sea surface at vertical and horizontal polarizations . . . . . . . . . . . . . . . . . . . Fragment of the space-frequency spectrum of a surface gravity wave system The experimental frequency spectra of sea surface elevations, measured using a string wave recorder at various stages in the development of roughness development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

205 212 214 214 216 218 219 220 225 229 230 233 234 236 236 237 242 243 244 246 248 249 254 255 257 258 259


Tables

2.1 2.2 2.3 2.4 2.5 3.1 3.2 3.3 4.1 4.2 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 8.1

Distribution parameters for the speci®c density of breaking centers . . . . . . . The sampling values of correlation coecient Rxy and their con®dence bounds for the ®ve zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The sea wave fetch conditions and distribution parameters for the waiting area Distribution parameters for the speci®c density of breaking centers . . . . . . . The sampling values of correlation coecient Rxy and their con®dence bounds The parameters and con®dential bounds for the distributions of foam structure geometrical sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The parameters and con®dential bounds for the distributions of foam area sizes Distribution parameters for the speci®c density of breaking centers . . . . . . . Conditions of ®eld experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Average characteristics of breaking zone geometry . . . . . . . . . . . . . . . . . . . Some physical parameters of sea water and foam structures . . . . . . . . . . . . Characteristics of the dispersive microstructure of sea foam . . . . . . . . . . . . Experimental values of emissivities for dispersive media over the waveband 0.26±18 cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental values of emissivities for dispersive media on the water surface Experimental values of the mirror re¯ection coecients for dispersive media Spectral characteristics for per unit length extinction and scattering albedo in a polydispersive bubble media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Formulae of the dielectric properties for diraction models . . . . . . . . . . . . . Comparison of radiothermal models for dispersive systems . . . . . . . . . . . . . Emissivities for foam structures: results of ®eld experiments and data of theoretical models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24 30 37 40 41 54 55 69 87 99 127 133 142 144 150 164 170 175 245


Abbreviations and acronyms

ADP AFA-100 AFA-TE-100 AN-30 DSP EBS ESA HF IL-14 IR IW JONSWAP LF MB MGPI MKF-6 OI PSD RAS RCS RFT RHV RTI RV SAS SRI VH and HV

Antenna Directional Pattern Type of Russian aerosurveying camera Type of Russian aerosurveying camera Antonov-30 (Russian research aircraft) Drop-Spray Phase Eective Backscattering Surface Eective Scattering Area High-Frequency ILyushin-14 (Russian aircraft) InfraRed Internal Wave Joint North Sea Wave Project Low-Frequency MesoBreaking Moscow State Pedagogical Institute Type of Russian space-borne multiband photographic camera Optical Image Polar Scattering Diagram Russian Academy of Sciences Radar Cross-Section Rapid Fourier Transformation Research Hydrographical Vessel Range±Time±Intensity (diagram) Research Vessel Surface-Active Substance Space Research Institute Cross-polarization