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Book reviews

Interaction of sea waves with wind

By Peter Janssen. Cambridge University Press (2004). viii + 300 pages. ISBN 0-521-46540-0 (h/b). Price: £70/US$ 120.

Surface gravity waves are well-known, complicated phenomenona, which have always been the subject of great interest. They are easily observed but difficult to describe mathematically. Many works have been devoted to wind wave investigation and this monograph by Peter Janssen is an important contribution.

About 20 years ago, the author was a member of the International  Wave Modelling Group (WAMDI). At present, the resulting WAM model is being improved, tested and widely used both at the global scale and in local water areas. The operational WAM model variant assimilates satellite information for updating the wave forecast. Nowadays it is one of the most popular wind wave models used in many countries.

Peter Janssen pays attention to the problem of interaction of atmospheric boundary layer and sea waves. Winds generate ocean waves but, at the same time, airflow is modified due to the loss of energy and momentum to the waves; thus, momentum from the atmosphere to the ocean depends on the state of the waves. Wind-wave numerical simulation is made on the basis of wave action balance equation.

Peter Janssen’s book describes ocean-wave evolution due to advection and physical processes such as wind input, dissipation and non-linear energy transfer in the wave spectrum. An overview of non-linear transfer is given and, as a by-product, the role of four-wave interactions in the generation of extreme events, such as freak waves, is discussed. Coupled ocean-atmosphere modelling gives improved weather and wave forecasts.

The problem of wind wave energy dissipation is not fully studied, however. Nowadays, there are at least two different approaches to dissipation description: that used in the WAM model, based on the influence of spectrum evolution almost in all the frequency domain and that proposed by V. Zakharov, according to which dissipation is located in the high frequency range.

By fitting the dissipation parameters, it is possible to achieve satisfactory agreement between numerical results and field data for wave evolution. But the effect of the ocean-atmospheric boundary layer interaction is principally different in these two cases as in the second case essential energy fluxes from ocean to atmosphere can exist.  It may contribute to the problem of weather forecast and climate prediction.

The author describes the algorithm of the energy balance equation numerical output used in the WAM model.  Nevertheless, not enough attention is paid to this problem. It is known that error due to insufficient accuracy of the numerical output can lead to the similar error produced by not well studied wind wave physics and incorrectness of wind speed used in numerical simulations.

The book is useful for students, engineers and scientists who are interested in the problem of ocean weather forecast and climate formation.

Igor V. Lavrenov


New books received for review in the WMO Bulletin

Monitoring and Predicting Agricultural Drought

Vijendra K. Broken, Arthur P. Cracknell, and Ronald L. Heatcote (Eds.).
ISBN 0-19-516234-X.xix + 472 pp. Price: US$ 124.50

Agricultural droughts affect whole societies, leading to increased food costs, threatened economies, and even famine. In order to mitigate such effects, researchers must first be able to monitor agricultural droughts and then predict them; however, no book currently focuses on accurate monitoring or prediction of these devastating kinds of droughts. The editors of Monitoring and Predicting Agricultural Drought have assembled a team of expert contributors to make a global study, describing biometeorological models and monitoring methods for agricultural droughts. These models and methods note the relationships between precipitation, soil moisture, and crop yields, using data gathered from conventional and remote sensing techniques. The coverage of the book includes probabilistic models and techniques developed worldwide. It concludes with coverage of climate change and resultant shifts in agricultural productivity, drought early warning systems and famine mitigation.


Encyclopedia of Weather and Climate

By Michael Allaby. Facts on File, New York (2002). ISBN 0-8160-4071-0 (two volumes). Price: US$ 150.

This two-volume encyclopedia summarizes present knowledge of weather and climate in 4 000 cross-referenced entries accompanied by nearly 300 maps, charts, diagrams, and photographs, with several appendixes and a 34-page index.

By moving from one entry to another, the encyclopedia can be used to learn how different processes cause the weather we experience day by day. It explains the causes of blizzards, ice storms, tornadoes, hurricanes and ice ages, as well as ordinary rain showers, dew and frost. It also recounts how meteorological instruments came to be invented and how they work. There are also brief accounts of the lives of some of the scientists who have contributed to the disciplines of climatology and meteorology.


Baroclinic Tides—Theoretical Modeling and Observational Evidence

Vasiliy Vlasenko, Nataliya Stashchuk and Koluman Hutter. Cambridge University Press (2005). ISBN 0-521-84395-2. xix + 351 pp. Price: £70/US$ 120.

This book demonstrates the analytical and numerical methods used to study the generation and evolution of baroclinic tides and, by comparison with experiments and observational data, shows how to distinguish and interpret internal waves. Strongly non-linear solitary internal waves, which are generated by internal tidal waves at the final stage of their evolution, are investigated in detail. This book is intended for researchers and graduate students of physical oceanography, geophysical fluid dynamics and hydro-acoustics.




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