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Dynamics in Atmospheric Physics
130
Book reviews
on certain orchids for the scent with which to attract females for mating. Deforestation, and alternatives to it, are also treated. Finally, Dr John Phillipson, Chairman of the Royal Society for Nature Conservation, discussed ‘The natural world : a global casino’, the effects of global warming on the biosphere, biodiversity and sustainable development. All in all, this is an impressive, factual, and thoughtprovoking book. M. J. RYCROFT Cranfield Institute of Technology
Dynamics in Atmospheric Physics, LINDZEN R. S., 1990, 352 pp. Cambridge University Press, f25.00 hb. This book is a collection of lecture notes, used by the author when giving graduate courses at Harvard and M.I.T. In his introduction the author emphasises that the book is not intended to be a comprehensive reference text. This is fair comment. Certainly after reading the book I do not see it as an authoritative basic source in the same category as other recent books in this subject area (e.g. those by Andrews, Holton or Leovy). The selection of topics to be covered is iconoclastic, the treatment of these topics is not particularly balanced and the historical viewpoint and the choice of references is a very persona1 one. The result is a book that is annoyingly superficial in some areas, but which includes welcome, in-depth treatments of subjects in which the author has a personal interest and in which he himself has made a very significant contribution during his career ; examples here are symmetric circulation models and atmospheric tides. The book provides a valuable source for, and commentary on, these and other topics. However, it cannot be unequivocally recommended as a self-contained introductory text. In his opening remarks in the first chapter the author states his hope ‘to avoid the notion that dynamical meteorology is simply the derivation of equations and their subsequent solution’. For this reason he begins in Chapters 2 and 3 by giving examples (simple energy-balance climate models and simple models of interactive stratospheric photochemistry and dynamics, respectively) where the introduction of transport effects (albeit in very simple representations) have striking effects. In both cases the description could surely be made clearer but the essential message comes across. Chapter 3 is a good illustration of the assets and the deficiencies of this book. The idea that is being presented is that transport can lead to distributions of chemical species that are far from photochemical equilibrium. A clever 4-box model is used to illustrate this point and it does so very well. But the presentation of the model is poor, the differential form of the equation of mass continuity is introduced when for the purposes of this model it isn’t really needed-and the elementary, but essential, point, that the flux between boxes is determined by the velocity on the shared boundary and the mixing ratio in the ‘upstream’ box. is never made explicitly. This might be tine for lecture notes, with the lecturer able to fill in details in respose to audience reaction, but for a book, to be read in isolation, it is a serious drawback. The important ideas of hydrostatic and geostrophic balance are introduced in Chapter 4 as, quite reasonably. the author argues that having these ideas available greatly expedites the discussion of observed atmospheric structures in Chapter 5. By the author’s own admission the treatment here of this basic material is ‘quick and dirty’, but there are instances where the description is dangerously misleading.
For instance, the characterisation of the Coriolis force as ‘merely a linearization of the centrifugal force’ is not one that stands up to careful scrutiny. Chapter 5 gives a fair introduction to the diversity of structure observed in the large-scale circulation on various space and time scales. in both the troposphere and the middle atmosphere. In Chapter 6 the equations of motion are introduced. Using the justification that clear derivations are available in other textbooks, the author adopts a non-standard approach attributed to Serrin, based on explicit transformation from Lagrangian to Eulerian coordinates. My feeling on reading this was that it might be useful for mathematically minded students who already had a basic grounding in fluid dynamics, but that for newcomers to the field the formidablelooking mathematics, with minimal accompanying text would prove too stern an obstacle. On this basis one might question whether the accompanying demonstration of the symmetry of the stress tensor and derivation of the energy equation is misplaced. A reader who had not already met this material would surely do better to look to basic fluid dynamics texts where such topics are explained more clearly and at greater length. The following chapter deals in depth with models of the symmetric circulation and includes a historical view of developments in our understanding of the theory of this circulation. The conceptually important Held and Hou model is described in detail, including its extension to asymmetric heating distributions. (The author has recently suggested that taking account ofthe seasonal asymmetry might account for the deficit in the predicted Hadley cell transport from that observed.) On the whole this chapter is a valuable account of this important aspect of our understanding of the general circulation. Chapters 8 and IO deal with internal gravity waves and are separated by a substantial Chapter 9 on atmospheric tides. The dispersion relation for internal gravity waves is derived by an ingenious heuristic argument and the text moves quickly to the topic of wave, mean-flow interaction, with the Elaissen-Palm theorems being derived under the assumption of linear, monochromatic waves. Whilst the author’s decision to introduce the topic in this way is perfectly valid. it seems a serious omission that no indication is given of how (or whether) the results extend to more general cases. Chapter 8 concludes with a substantial set of exercises investigating various properties of (linear) internal gravity waves using a numerical model, the source code being supplied in an appendix at the end of the book. Chapter IO deals with the effects of background shear, including behaviour near critical levels and thereby leads to a simple description of the interaction of waves and mean Rows and a short account of the Holton -Lindzen-Plumb mechanism for the quasi-biennial oscillation. (The associated explanation for the existence of equatorially trapped gravity waves seems curious and somewhat implausible.) The subject of atmospheric tides is one to which the author has made important contributions and the treatment here includes a substantial historical review. In addition there is a detailed summary of relevant observations followed by an account of the theory necessary for the prediction of tidal amplitudes, This is surely the most thoroughly covered topic in the book; it is interesting and enjoyable to read. Two chapters follow on Rossby waves and on quasi-geostrophic theory. Rossby waves are introduced by considering the shallow water equations in a b-plane channel. The full dispersion relation is derived which reduces to the quasi-
Book reviews geostrophic version in the low-frequency limit. An account of the Stommel solution for the wind-driven circulation is inserted after the material on Rossby waves. However, since the chance is missed to make a link between the Stommel solution and the basic dispersive properties of Rossby waves, one is left feeling that that is an unnecessary distraction. The final two chapters of the book are concerned with fluid dynamical instabilities. Some of the material is standard; some reflect the very personal views of the author (e.g. the idea that the ‘Orr mechanism’ is the basis of shear instability). A fairly detailed account of the energetics of barochnic instability is followed by discussion of baroclinic adjustment and the possibility that the observed latitudinal temperature gradient in the extratropics is primarily controlled by the action of baroclinic instability. It is difficult to see this book becoming a standard text in its field. (It must be remembered that the author issues a
131
disclaimer on this point, but also noted that the publisher’s jacket description describes it as ‘a text for first-year graduate students’ that is ‘self-contained’.) To fill such a role a great deal of revision would be needed. There are many typographical errors and many internal inconsistencies, For example, terms such as ‘geostrophic adjustment’ arise in the text without previous definition. It is difficult to believe that the author would be able to read some of his statements without, in retrospect, a little embarrassment. However, precisely because much of the presentation is nonstandard and in a very personal style, the book is a useful and stimulating source on many topics, which will be useful in research or in course preparation, and it can be recommended on this basis, P. H. HAYNES Department of Applied Mathematics and Theoretical Physics, University of Cambridge
Book reviews
on certain orchids for the scent with which to attract females for mating. Deforestation, and alternatives to it, are also treated. Finally, Dr John Phillipson, Chairman of the Royal Society for Nature Conservation, discussed ‘The natural world : a global casino’, the effects of global warming on the biosphere, biodiversity and sustainable development. All in all, this is an impressive, factual, and thoughtprovoking book. M. J. RYCROFT Cranfield Institute of Technology
Dynamics in Atmospheric Physics, LINDZEN R. S., 1990, 352 pp. Cambridge University Press, f25.00 hb. This book is a collection of lecture notes, used by the author when giving graduate courses at Harvard and M.I.T. In his introduction the author emphasises that the book is not intended to be a comprehensive reference text. This is fair comment. Certainly after reading the book I do not see it as an authoritative basic source in the same category as other recent books in this subject area (e.g. those by Andrews, Holton or Leovy). The selection of topics to be covered is iconoclastic, the treatment of these topics is not particularly balanced and the historical viewpoint and the choice of references is a very persona1 one. The result is a book that is annoyingly superficial in some areas, but which includes welcome, in-depth treatments of subjects in which the author has a personal interest and in which he himself has made a very significant contribution during his career ; examples here are symmetric circulation models and atmospheric tides. The book provides a valuable source for, and commentary on, these and other topics. However, it cannot be unequivocally recommended as a self-contained introductory text. In his opening remarks in the first chapter the author states his hope ‘to avoid the notion that dynamical meteorology is simply the derivation of equations and their subsequent solution’. For this reason he begins in Chapters 2 and 3 by giving examples (simple energy-balance climate models and simple models of interactive stratospheric photochemistry and dynamics, respectively) where the introduction of transport effects (albeit in very simple representations) have striking effects. In both cases the description could surely be made clearer but the essential message comes across. Chapter 3 is a good illustration of the assets and the deficiencies of this book. The idea that is being presented is that transport can lead to distributions of chemical species that are far from photochemical equilibrium. A clever 4-box model is used to illustrate this point and it does so very well. But the presentation of the model is poor, the differential form of the equation of mass continuity is introduced when for the purposes of this model it isn’t really needed-and the elementary, but essential, point, that the flux between boxes is determined by the velocity on the shared boundary and the mixing ratio in the ‘upstream’ box. is never made explicitly. This might be tine for lecture notes, with the lecturer able to fill in details in respose to audience reaction, but for a book, to be read in isolation, it is a serious drawback. The important ideas of hydrostatic and geostrophic balance are introduced in Chapter 4 as, quite reasonably. the author argues that having these ideas available greatly expedites the discussion of observed atmospheric structures in Chapter 5. By the author’s own admission the treatment here of this basic material is ‘quick and dirty’, but there are instances where the description is dangerously misleading.
For instance, the characterisation of the Coriolis force as ‘merely a linearization of the centrifugal force’ is not one that stands up to careful scrutiny. Chapter 5 gives a fair introduction to the diversity of structure observed in the large-scale circulation on various space and time scales. in both the troposphere and the middle atmosphere. In Chapter 6 the equations of motion are introduced. Using the justification that clear derivations are available in other textbooks, the author adopts a non-standard approach attributed to Serrin, based on explicit transformation from Lagrangian to Eulerian coordinates. My feeling on reading this was that it might be useful for mathematically minded students who already had a basic grounding in fluid dynamics, but that for newcomers to the field the formidablelooking mathematics, with minimal accompanying text would prove too stern an obstacle. On this basis one might question whether the accompanying demonstration of the symmetry of the stress tensor and derivation of the energy equation is misplaced. A reader who had not already met this material would surely do better to look to basic fluid dynamics texts where such topics are explained more clearly and at greater length. The following chapter deals in depth with models of the symmetric circulation and includes a historical view of developments in our understanding of the theory of this circulation. The conceptually important Held and Hou model is described in detail, including its extension to asymmetric heating distributions. (The author has recently suggested that taking account ofthe seasonal asymmetry might account for the deficit in the predicted Hadley cell transport from that observed.) On the whole this chapter is a valuable account of this important aspect of our understanding of the general circulation. Chapters 8 and IO deal with internal gravity waves and are separated by a substantial Chapter 9 on atmospheric tides. The dispersion relation for internal gravity waves is derived by an ingenious heuristic argument and the text moves quickly to the topic of wave, mean-flow interaction, with the Elaissen-Palm theorems being derived under the assumption of linear, monochromatic waves. Whilst the author’s decision to introduce the topic in this way is perfectly valid. it seems a serious omission that no indication is given of how (or whether) the results extend to more general cases. Chapter 8 concludes with a substantial set of exercises investigating various properties of (linear) internal gravity waves using a numerical model, the source code being supplied in an appendix at the end of the book. Chapter IO deals with the effects of background shear, including behaviour near critical levels and thereby leads to a simple description of the interaction of waves and mean Rows and a short account of the Holton -Lindzen-Plumb mechanism for the quasi-biennial oscillation. (The associated explanation for the existence of equatorially trapped gravity waves seems curious and somewhat implausible.) The subject of atmospheric tides is one to which the author has made important contributions and the treatment here includes a substantial historical review. In addition there is a detailed summary of relevant observations followed by an account of the theory necessary for the prediction of tidal amplitudes, This is surely the most thoroughly covered topic in the book; it is interesting and enjoyable to read. Two chapters follow on Rossby waves and on quasi-geostrophic theory. Rossby waves are introduced by considering the shallow water equations in a b-plane channel. The full dispersion relation is derived which reduces to the quasi-
Book reviews geostrophic version in the low-frequency limit. An account of the Stommel solution for the wind-driven circulation is inserted after the material on Rossby waves. However, since the chance is missed to make a link between the Stommel solution and the basic dispersive properties of Rossby waves, one is left feeling that that is an unnecessary distraction. The final two chapters of the book are concerned with fluid dynamical instabilities. Some of the material is standard; some reflect the very personal views of the author (e.g. the idea that the ‘Orr mechanism’ is the basis of shear instability). A fairly detailed account of the energetics of barochnic instability is followed by discussion of baroclinic adjustment and the possibility that the observed latitudinal temperature gradient in the extratropics is primarily controlled by the action of baroclinic instability. It is difficult to see this book becoming a standard text in its field. (It must be remembered that the author issues a
131
disclaimer on this point, but also noted that the publisher’s jacket description describes it as ‘a text for first-year graduate students’ that is ‘self-contained’.) To fill such a role a great deal of revision would be needed. There are many typographical errors and many internal inconsistencies, For example, terms such as ‘geostrophic adjustment’ arise in the text without previous definition. It is difficult to believe that the author would be able to read some of his statements without, in retrospect, a little embarrassment. However, precisely because much of the presentation is nonstandard and in a very personal style, the book is a useful and stimulating source on many topics, which will be useful in research or in course preparation, and it can be recommended on this basis, P. H. HAYNES Department of Applied Mathematics and Theoretical Physics, University of Cambridge