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CITATION Church, J.A. 2015. Review of Sea-Level Science: Understanding Tides, Surges, Tsunamis and Mean Sea-Level Changes, by D. Pugh and P. Woodworth. Oceanography 28(1):177–178, http://dx.doi.org/10.5670/oceanog.2015.24.

DOI http://dx.doi.org/10.5670/oceanog.2015.24

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DOWNLOADED FROM HTTP://WWW.TOS.ORG/OCEANOGRAPHY SEA-LEVEL SCIENCE: UNDERSTANDING TIDES, SURGES, TSUNAMIS AND MEAN SEA-LEVEL CHANGES

By David Pugh and Philip Woodworth, Cambridge University Press, Cambridge, UK, 395 pp., ISBN 978-1-107-02819-7, Hardcover $99 US

Reviewed by John A. Church

book Tides, Surges and Mean Sea-Level. description of tidal forces begins with the The new book brings these topics up to basic ideas of gravitational attraction and date and provides additional information then develops the concept of the equilib- related to climate change and variabil- rium tide of the Earth-Moon-Sun system. ity as well as results from modern satel- This leads to identification of the basic lite observing systems and related analy- astronomical frequencies and a descrip- he ocean surface provides pathways sis. The book is well written by two of the tion of tidal patterns and their inter- Tfor shipping and fishing activities leading scientists in these fields, is easy to annual to decadal variations. These fre- and is the reference level marine scien- understand despite the underlying com- quencies lead directly to the harmonic tists use when measuring ocean interior plexity of the science, and is well illus- and response methods used for the anal- properties. Its intersection with land trated with high-quality diagrams and ysis and prediction of surface height and forms coastal environments import- photographs. Each chapter begins with a ocean current observations. ant for marine ecosystems, coral reefs, few lines of poetic introduction and ends The excitation of long ocean waves coastal fisheries, and many of our recre- with a comprehensive, but not exhaus- (wavelengths of thousands of kilome- ational activities. We are all familiar with tive, list of references. ters in the deep ocean) by tidal forces is the ocean’s surface but, in general, take its The Introduction (Chapter1) pro- responsible for the transfer of tidal energy existence for granted, pay little attention vides a general background and outlines around Earth and results in observed to its spatial and temporal variability, and early ideas and observations. This is fol- tidal patterns being very different from are unfamiliar with its importance. lowed by a brief description of tidal pat- the equilibrium tide. Chapter 5 focuses The spatial and temporal variability terns around the world, with some illus- on the nature of these waves, how they of the ocean surface ranges from small- trative examples of tidal observations and interact to result in observed tidal pat- scale, high-frequency ripples to energetic of meteorological and other nontidal sea terns, and the idea of ocean resonance. wind-driven surface waves, ocean tides, level changes, including a brief mention A number of examples are very informa- and storm surges, and on to basin- and of storm surges and tsunamis and their tive. The impact of changes in the atmo- global-scale low-frequency climate vari- impacts. Chapter 1 concludes with defi- sphere related to the cycles of solar radia- ability and change signals. This variabil- nitions of common terms and gives the tive forcing and the response of the solid ity is of immense economic and environ- reader a good overview of sea level vari- Earth to gravitational forces are also dis- mental importance. ability, with a useful discussion of some cussed. There is a brief but incomplete Sea-Level Science: Understanding simple statistics and the spectrum of sea section on internal tides. Although this Tides, Surges, Tsunamis and Mean Sea- level variability. Chapter 2 introduces his- concept is picked up again in Chapter 6, Level Changes by David Pugh and Philip torical sea level measuring techniques, the incompleteness of this section is per- Woodworth is a great introduction to a from tide poles, to tide gauges, to GPS haps surprising and a little disappointing, broad interdisciplinary spectrum of sea technology, and provides an important given the importance of internal tides level variability and change topics. The discussion of datum control. It is a very to global ocean circulation. The last sec- subjects range from tidal frequencies to useful introduction to anyone beginning tion of this chapter discusses long-term the centennial changes related directly to analyze sea level data or manage a sea changes in tides and their relationship to climate change and the emission of level observing network. to local bathymetric changes. Chapter 6 anthropogenic greenhouse gases, and Tidal analysis is a seemingly com- deals with the generation of shallow include the most important issues fac- plex field for the newcomer, with histor- water tides from nonlinear interaction, ing society today. Though surface waves ical developments sometimes obscuring their impacts on tidal currents (both the are mentioned in various chapters of the the simplicity of the underlying ideas. In high-frequency components and also the book, they are not the central focus. Chapters 3 and 4, the reader is led through important low-frequency residual cur- The first six chapters generally fol- the concept of the tidal forces and the rents), and tidal asymmetries. The inter- low the course of David Pugh’s earlier closely related topic of tidal analysis. The esting phenomenon of tidal bores is also

Oceanography | March 2015 177 Upcoming introduced with some regional examples. land motion and provides a brief discus- Chapter 6 concludes the consideration of sion of the major factors leading to this Oceanography tides with a brief description of the global motion. This consideration includes tec- Special Issues tidal energy budget. tonic factors associated with Earth’s mov- Extreme high sea levels from storm ing lithosphere (crust and upper mantle), surges (Chapter 7) and tsunamis changes in the surface loading of Earth by Vol 28 | No 2 | Jun 2015 (Chapter 8) have wreaked havoc in many the changing distribution of ice and water Emerging Themes in Ocean Acidification Science regions of the world. The generation of from both past (glacial isostatic adjust- storm surges by atmospheric pressure ment) and present-day (elastic response) Vol 28 | No 3 | Sep 2015 and winds, the phenomena of wave setup changes, and the processes of sediment Russian American Long-Term Census of the Pacific Arctic and runup, and changes in the statistics compaction and movement by waves and of extreme sea levels and other meteoro- ocean currents. Vol 28 | No 4 | Dec 2015 A New Look at the Low-Latitude logical effects on sea levels are all consid- The final two chapters discuss applica- Western Pacific ered. Chapter 8 is a fascinating discussion tions of our knowledge of sea level vari- of the generation of tsunamis by move- ability and change. Chapter 12 considers Vol 29 | No 1 | Mar 2016 Graduate Education in ments of the ocean floor, their propaga- the issues of managing the coastal region, the Ocean Sciences tion around the world and into coastal coastal defenses and associated economic regions, and the options for establishing issues, flood warning systems, and power observing and warning systems. generation. Finally, Chapter 13 consid- Satellites have revolutionized our ers the impacts of sea level variability approach to and understanding of sea and change on coastal ecosystems and on Upcoming level and its spatial variation. Chapter 9 humans; the authors note that sea level begins with a comprehensive and insight- exerted control on past human migra- Events ful introduction to the international tions, as recorded in myths and traditions. terrestrial reference frame (an essen- This chapter also discusses the implica- 7th Symposium on tial underpinning of the satellite altime- tions for changes in sea level during the Gas Transfer at Water Surfaces May 18–21, 2015, Seattle, WA, USA try revolution), measurements of Earth’s twenty-first century. However, the poten- http://www.gtws7.org gravitation field from space, and hence tially dramatic effects of the longer-term the determination of the geoid (the equi- evolution of sea level that could result Second International Ocean Colour Science Meeting potential surface of a stationary ocean) from significant loss of ice sheet mass June 16–18, 2015, San Francisco, CA, USA and the mean sea surface. receive little attention. http://iocs.ioccg.org Chapter 10 deals with the critically Despite the minor omissions, Sea-

OCEANS ‘15 MTS/IEEE important issue of changes in sea level Level Science is an excellent book that October 19–22, 2015, Washington, DC, USA with time. It considers long-period tides, offers comprehensive coverage of a broad http://www.oceans15mtsieeewashington.org the seasonal cycle, ocean mesoscale vari- spectrum of elements of sea level science 2016 Ocean Sciences Meeting ability, changes in atmospheric pressure, important to today’s (and tomorrow’s) February 21–26, 2016, New Orleans, LA, USA patterns of interannual variability related society. No one working in the area of sea http://meetings.agu.org/meetings/os16 to climate modes and long-term changes level science or its applications, includ- in sea level over ice-age cycles, and lastly ing policymakers, government officials, the increasing rate of rise resulting from coastal engineers and planners, research- the burning of fossil fuels. For the lat- ers, and students, should be without ter, paleo, tide-gauge, and satellite obser- access to a copy. The book will be par- vations are all considered. The current ticularly useful to new entrants to the understanding of the reasons for that field as it constitutes an easy and broad change (ocean thermal expansion and introduction to what can be a bewil- loss of mass from glaciers and ice sheets) dering and diverse field of observa- and projections for the twenty-first cen- tions and theory. tury are briefly discussed. No book on sea level would be com- REVIEWER. John A. Church ([email protected]) is a CSIRO Fellow, Centre for Australian Weather and plete without a discussion of movement Climate Research and CSIRO Ocean and Atmosphere of the solid Earth. Chapter 11 introduces Flagship, Hobart, Australia. the techniques for measuring vertical

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