This article has been published in published been This has article or collective redistirbution other or collective or means this reposting, of machine, is by photocopy article only anypermitted of with portion the approval The O of Book Reviews

Ebb and Flow and Life on Our Once and Future Planet

, V By Tom Koppel, The Dundurn Group, which is the loss of much of the fleet of olume 21, Number 2, a quarterly 21, Number olume The O journal of 2007, 296 pages, ISBN 9781550027266, Alexander the Great due to a ), Paperback, $26.99 US coastal ecosystems, modern analysis, and extracting energy from tides. Chapter 1 Reviewed by John L. Luick contains an account of the ancient tidal dockyards at Lothal, India—surely a can- Ebb and Flow: Tides and Life on Our didate for “Engineering Wonders of the Once and Future Planet is well titled. It Ancient World.” The most ambitious and tells the story of tides, why they matter, original chapter is the final one, whose ceanography Society. C what causes them, and how they have three subheadings are Change changed over time. The author, Tom Causes Intertidal Zones to Migrate; Giant all sorts of ammonia and phosphoric Koppel, is not an analyst or theoretician Ancient Tides and Earth’s Rotation; and salts.” Again, tides are shown to play a of tides but a man of inquisitive mind The Origin, Evolution, and Future of Life crucial role in both the origin and the opyright 2008 by The O and substantial beachcombing and on Earth. The subject of the first section evolution of life on earth, with polymer- sailing experience. He tells his stories in may seem self-evident, but Koppel does a ization made possible by repeated cycles an engaging style, be they of gathering great job of developing it, beginning with of tidal-pool drying. clams on tidal flats or harrowing escapes an anecdote concerning dieback among I have seen many nonmathematical ceanography Society. All rights reserved. Permissionceanography is Society. Allreserved. rights granted to in teaching copy this and research. for use article Republication, systemmatic reproduction,

ceanography Society. Send all correspondence to:ceanography Society. Send [email protected] Th e O or from tidal races. They are woven into trees he found on the shores of British attempts to explain how the moon and a well-paced and thoughtful narrative, Columbia. Clearly, the trees had grown sun combine to cause tides on earth, and never straying far from the tidal theme. to maturity at a time when the local rela- have yet to find a satisfactory one. (Most Most of the chapters combine two tive sea level was at least a meter lower. of the mathematical ones are equally elements—typically, a story of how tides This story provides a nice lead-in to a unenlightening.) Without the simplify- have played a defining role in the lives discussion of local tectonics, and from ing power of potential theory and of a coastal people, and a discussion of there to how macrotidal embayments Legendre polynomials, one inevitably the related natural history. For example, like the Bay of Fundy became tuned must resort to counterintuitive devices Chapter 9 begins with the story of how to resonate with external tidal forcing such as “revolution without rotation,” certain coastal Native Americans harvest as global mean sea level changed since confusing diagrams with lots of circles a small fish (eulachon), describes the the last ice age. The second subheading and arrows, and a balance between involvement of tides, and then broadens considers how tides have evolved over gravitational and centrifugal forces in

ceanography Society, P the discussion to include tides in coastal millennia from a time when the moon a rotating reference frame. No wonder, ecosystems generally. This format suits was much closer and days much shorter. then, that the subject has a well-deserved the topic well, successfully drawing in As Koppel poetically put it, “the record reputation for being arcane—especially the reader and maintaining interest. of these changes is written in limestones, if the derivation (quite unnecessarily)

Box 1931, Rockville, MD 20849-1931, USA. 1931, Rockville, O Box Koppel ranges over many historical, corals, and seashells” (rhythmites, rugose employs “fictitious stars” (two each for scientific, and practical aspects of tides: corals, and nautaloid cephalopods, as he the moon and sun, to account for their what the “ancients” thought of them, goes on to explain). The third subhead- diurnal and semidiurnal effects) and the

the advances in understanding from the ing takes us back to the origin of life. individual frequencies, like M2, are given

1600s to the present, the effect on the A well-known speculation of Charles names like, well, “M2.” Koppel makes a morphology of shorelines, various disas- Darwin sets the stage: “[perhaps life brave attempt, but he probably would ters attributable to tides (not the least of started in] some warm little pond with have done better to have simply stated

Oceanography June 2008 77 a few of the fundamental results, such emphasis is a bit misleading because the term itself is not used, which seemed as that the -generating forces on Laplace’s progressive wave theory and like a missed opportunity in terms of Earth’s surface are inversely proportional dynamics remain the foundation of organizing things. Fourth, the book to the cube of the distance from either modern tidal hydrodynamic modeling. would have benefited from an index. the moon or sun, and then referred the It was really only the highly simpli- Fifth, showing the sense of rotation interested reader to a Web site such as fied version (for which Laplace found around the amphidromes in Figure 12 NOAA’s “Our Restless Tides,” which at analytic solutions) that turned out would have helped elucidate the text. least has some nice graphics. Actually, to be unrealistic. Finally, I noticed a couple of typos. the only mention of an inverse cube My few remaining negatives are This book will be of interest to those relationship (page 276) is incorrectly minor. First, the reproductions of pho- with affinities for natural history, seafar- stated (it would be correct if the words tographs mostly look like poor scans of ing, and tides in general—and even tidal “tide-generating forces” were substituted color prints. Second, I am allergic to the scientists will learn a few things about for “gravity”). The inverse cube relation- “National Geographic School of Writing” their science. ship is always surprising when first (the tale begins with a dramatic state encountered by anyone with basic phys- of affairs, then reverts back to tell how John L. Luick ([email protected]) ics training, in which one is taught that it came to pass, and finally reveals the is an oceanographer working for the South the gravitational attraction between two finale). Luckily, Koppel did not overuse Australian Research and Development bodies varies as the inverse square. the formula and my allergic rash disap- Institute and President, AusTides, Ltd. In Chapters 8 and 12, much is made peared quickly. Third, although in sev- Previously, he worked at the Australian of the shortcomings and ultimate failure eral places the book discusses phenom- National Tidal Facility (now the National of the “progressive wave theory.” This ena that are in fact circadian rhythms, Tidal Centre).

Lagrangian Analysis and Prediction of Coastal and Dynamics

Edited by Annalisa Griffa, Atmosphere) had previously sponsored A.D. Kirwan Jr., Arthur J. Mariano, similar meetings, which mostly involved Tamay Özgökmen, and H. Thomas European researchers; the proposed Rossby, Cambridge University Press, LAPCOD (Lagrangian Analysis and 2007, 487 pages, ISBN 9780521870184, Prediction of Coastal and Ocean Hardcover, $160 US Dynamics) would offer greater participa- tion by American scientists. Several of Reviewed by Joseph H. LaCasce the organizers were from Miami and Italy, and thus there have been meet- During a colloquium on Lagrangian ings in Ischia, Italy (2000); Key Largo, dynamics in Liège, Belgium, in 1999, Florida (2002); and Lerici, Italy (2005). several participants discussed convening (I recall thinking, while enjoying several eclectic flavor. Although current meters a meeting devoted to Lagrangian stud- outstanding fish dishes near the harbor produce fairly straightforward data ies in the ocean and atmosphere. The in Lerici, that having an Italian as one of (e.g., a time series of velocity at a fixed European Science Foundation program the organizers was a good choice.) location and depth), floats and drifters TAO (Transport in the Ocean and Lagrangian studies have always had an move about, providing the drifter posi-

78 Oceanography Vol.21, No.2 given in the introduction) than on the present-day drifter. There are currently upcoming BOOK Reviews 1312 surface drifters in the main ocean

Arc Marine: GIS for a Blue Planet basins as part of the Global Drifter by Dawn J. Wright, Michael J. Blongewicz, Patrick N. Halpin, and Joe Breman, Program (GDP), and the authors discuss ESRI Press, 216 pages how these drifters track currents with a subsurface drogue, how they are tracked Climate Change: A Multidisciplinary Approach by William James Burroughs, Cambridge University Press, 378 pages by satellite, and how the satellite posi- tions are interpolated. The authors even Past: Management Insights from the History of Marine Animal Populations suggest the best way to deploy drifters by David J. Starkey, Paul Holm, and Michaela Barnard, Earthscan, 223 pages from a boat (from the stern, not more Our Changing Planet: The View from Space than 10 m from the surface). They exam- Edited by Michael King, Claire Parkinson, Kim Partington, and Robin Williams, ine such issues as wind slippage and the Cambridge University Press, 390 pages Ekman drift and then summarize results from a number of studies, concerning, Tides of History: Ocean Science and Her Majesty’s Navy by Michael S. Reidy, University of Chicago Press, 392 pages for instance, surface kinetic energy, dif- fusivities, and the synthesis of drifter and satellite data. The chapter is a concise and useful overview of the subject. Chapter 3 was inspired by a Key Largo meeting section entitled “My Favorite Trajectory.” Drifters often seem to have tion as a function of time, and perhaps of the instruments or invented them minds of their own, and their paths also the ambient temperature and salin- himself, from Swallow’s float in the can be surprising. The chapter provides ity. Because the positions vary continu- 1960s, to the SOFAR float in the 1970s, examples from floats in the Red Sea, ously, it can be difficult to interpret the and the RAFOS float in the 1980s. North and tropical Atlantic, and South results. So what exactly can one do with He also discusses recent designs, like China Sea. Three SOFAR floats from Lagrangian data? the profiling ALACE, and floats that the POLYMODE experiment in the late The present book seeks to answer track vertical motion in the mixed 1970s traveled some 700 km without that question. Rather than being a layer or motion along constant-depth separating (counter to expectations proceedings volume, collecting a set of contours. The chapter is full of technical about turbulent ). My favorite specialized papers, the book presents information, for instance, how to make trajectory, though, was from a surface reviews that flesh out different aspects of an isopycnal float using a spring and a drifter launched off Iceland. This drifter Lagrangian studies. Thus, the chapters piston, and how sound is transmitted via rounded the tip of Greenland, crossed take a broader perspective than indi- the SOFAR channel. It also considers sig- the entrance to the Labrador Sea, left the vidual authors’ own work. The result nificant findings from a number of float slope at Newfoundland, and continued is a potpourri of different results and experiments. The anecdotes from the (albeit chaotically) back to Iceland. From analyses, and a useful volume for anyone early experiments, at a time when ocean there, it retraced its original track, down interested in Lagrangian data. theory and float engineering were in to Newfoundland again. I was reminded The first two chapters concern the their infancy, make entertaining reading. of Farley Mowat’s schooner in The Boat instruments—the subsurface float and Chapter 2 (by R. Lumpkin and Who Wouldn’t Float. surface drifter. Chapter 1 (by T. Rossby) M. Pazcos) deals with surface drifters. One way to understand drifter discusses float development. The author The focus here is less on their develop- behavior is by using models. Similarities either witnessed the invention of many ment (although a short history is between in situ dispersion and that

Oceanography June 2008 79 seen in a model, whose dynamics we models, while floats in less-energetic correlated motion between nearby par- (hopefully) understand, can help unravel regions (i.e., the eastern Atlantic) can ticles, to this end. what is happening in the full system. In be studied with lower-order models. Assimilation in oceanic general addition, model statistics are generally This distinction provides a useful way of circulation models is taken up in much better. A typical float experiment categorizing trajectories. Chapter 7 (by A. Molcard and others). may have 50 to 100 instruments, but it I recall an oceanographer who They note there are three central issues: is feasible to have thousands of particles remarked that we didn’t have much to how to incorporate drifter positions or in a model. show for our years of Lagrangian study. velocities into the model, how to adjust Chapter 4 (by C. Pasquero and others) “What use are floats to a modeler?” other variables (e.g., layer thickness), discusses dispersion in turbulent flows. he wondered. The answer may well be and how to modify variables in the layers Numerical simulations show that coher- Lagrangian data assimilation. Global not sampled by the drifters. Molcard ent vortices play an important role in array floats and GDP drifters et al. illustrate how each issue can be turbulent flows, and these flows affect offer sampling that was unimaginable addressed using examples from single Lagrangian dynamics. Vortices trap until recently. Assimilation offers a way and multilayer ocean models. The results fluid, preventing it from mixing with to exploit these data in models. are often astonishingly good, illustrat- the surroundings, and also produce Chapters 6, 7, and 8 treat various ing how useful Lagrangian data can anomalously large advection speeds. aspects of the assimilation problem. be. Chapter 8 considers interpolation The authors discuss how vortices, Although there is overlap among authors techniques that conserve scalar proper- superimposed on a random background and the material, the viewpoints are ties, such as temperature and vorticity, flow, can be represented with stochastic interestingly different. Chapter 8 (by and reconstruction of the velocity field models, which in turn could be used for M. Chin and others) presents a concise in the vicinity of an observed trajectory. simulating marine dispersion. They also background on Lagrangian assimilation, The advantages of various methods are discuss how turbulent dispersion affects from the early attempts to generate considered, as are the technical and plankton distributions and hence the streamfunction maps from SOFAR practical challenges (such as assimilating carbon cycle. Chapter 5 (by N. Paldor) trajectories to the incorporation of trajectories near saddle points). considers a specific phenomenon— Lagrangian velocities and trajectories Ocean biology is another area where particles undergoing inertial oscillations into models. All three chapters consider Lagrangian processes are undoubtedly on a sphere—and examines the behavior sequential assimilation, and the Kalman important. Plankton are advected as analytically. The particles exhibit a filter in particular, and each presents passive tracers, carried into the euphotic Stokes-type drift, which can be derived examples from idealized and realistic zone, and then strained laterally by the using Hamiltonian methods. ocean simulations as well. But from there currents. Fish are also transported by Chapter 9 (by V. Rupolo) is also the material diverges. currents, but they can swim, making concerned with stochastic models and Chapter 6 (by L. Piterbarg and oth- them active tracers. In both cases, how they can be exploited to under- ers) treats the problem of Lagrangian Lagrangian analyses can be used to stand dispersion and the Lagrangian predictability. Where will a sailor falling understand and predict behavior. power spectra. There is a hierarchy overboard at 39°N, 90°W at midnight Chapters 10–12 are devoted to of stochastic models, from the simple be in 36 hours? The US Coast Guard biological processes. Chapter 11 (by random walk up to higher-order models, performs some 5000 search and rescue G. Hitchcock and R. Cowen) focuses on which resolve the decorrelation of the operations per year, so the issue defi- passive advection, specifically plankton. Lagrangian acceleration or even simulate nitely arises. Predictability can be char- Plankton were actually used in the looping motion. Choice of model acterized by how rapidly two particles early 1900s to identify water masses depends on the temporal resolution deployed close to one another separate. (before it was realized that they could of the in situ data. Simulating floats in The authors discuss use of multiparticle be mixed laterally from other sources). energetic regions demands higher-order stochastic models, which account for The authors discuss a number of such

80 Oceanography Vol.21, No.2 studies in which plankton were observed ing a wide-ranging overview of observa- directly, before examining studies where tions, experiments, and techniques. They the motion was examined in conjunc- discuss the use of drift information, from tion with drifters, floats, and dye. This ships, bottles, and tracked instruments chapter is a very thorough overview to estimate mean velocities. Mariano of the subject. and Ryan also consider how seasonal Chapter 10 (by D. Olsen) is concerned variability, topography, and shear affect more with the active tracers. Modeling those estimates. They then examine these animals requires specifying how single-particle and relative dispersion, they move. Mean field models (the and experiments measuring each. Recent “average fish” representation) are inad- studies involving dynamical systems equate at capturing the evolution except theory are touched upon, as are bio- under ideal conditions, so a structured logical applications, stochastic models, population model is used in which the numerical simulations, and assimilation. dependence on space, time, mortality The authors close by noting expected conditions, and metabolism are all speci- developments. It is an informative and fied. Both this chapter and Chapter 11 very readable overview, and because the present specific examples from the authors touch on the major subjects in ocean, boundary currents, eddies, and the book, the reader could easily start fronts. Olsen cites an example of a right here before moving on to the topic- whale that had become entangled in specific chapters. fishing net. A transponder was placed in The book is a diverse and frequently the net and the whale was subsequently illuminating statement of our current tracked as it swam along the understanding of Lagrangian processes front from Cape Hatteras to the Azores. in the ocean. It perhaps lacks the Chapter 12 (by G. Buffoni and others) coherent style that one expects with examines the application of a stochastic a single author, but the changes in model to simulating plankton. To cap- perspective, for example, among the ture the behavior of a single organism, three chapters treating assimilation, are the model must represent such processes in themselves useful. Those attending as hatching, molting, reproduction, and LAPCOD meetings are struck by the death. This particular model was devel- energy and diversity of the participants oped to simulate insects, but is applied and their dedication to this unusual here to copepods, and specifically plank- study. The book captures that feeling. ton in the Mediterranean Sea. While It will certainly be useful to anyone reading these chapters, I was repeatedly interested in Lagrangian dynamics, struck by the complexity of both observ- modeling, or experiments. ing and modeling biological processes in the presence of evolving oceanic flows. Joseph H. LaCasce ([email protected]) The primary goal of the final chapter is Professor, Department of Geosciences, (by A. Mariano and E. Ryan) is to University of Oslo, Oslo, Norway. summarize results discussed during the three LAPCOD meetings. However, the authors take a much broader view, offer-

Oceanography June 2008 81