|BACK to WMO|
|August 2007||Downloads & Links|
In the press
Marine turbulence: theories, observations and models
Helmut Z. Baumert, John H. Simpson and Jürgen Sündermann (Eds.)
Turbulence is not an easy subject, because physics of turbulent processes has still unclear areas, relevant field measurements need very sophisticated techniques and appropriate numerical models are complex.
This book is a valuable outcome of the research undertaken during the three-year (1999-2001) Project CARTUM (Comparative Analysis and Rationalization of second-moments Turbulence Models), financed by the European MAST Programme. It has contributions from many authors of world renown in the field and is divided into eight parts, each one with an editor chosen from among the book contributors. The prologue and epilogue of each part give the reader a broad perspective of the respective subjects.
The physics of turbulence is the first topic to be introduced in Part I, with an insight of the characteristics of turbulent flows followed by the presentation of equation turbulence closure approaches to homogeneous shear and stratification and then to spatially non-uniform conditions. The intermittent character of turbulence is examined and various cascade models are presented. Part I closes with an overview of horizontal mixing processes in the upper ocean.
Part II deals with the difficult task of measuring oceanic turbulence, presenting the technological progress of the observational methods during the last 40 years, including horizontal and vertical profilers, microstructure optical probes, acoustic Doppler profilers and other more recent techniques.
Several aspects of numerical methods and their specific limitations for the modelling of turbulence are presented in Part III. In the respective chapters, subjects such as direct and large-eddy simulation, data assimilation, the physical principles and applications of the General Ocean Turbulence Model and its coupling to 3-D ocean models are discussed.
The oceanic surface and bottom layers have a turbulent structure which is analysed in Part IV. Aspects such as the effect of breaking waves on the top centimetre of the ocean or the interaction of the surface wave field with the wind-driven flow field, giving rise to Langmuir circulations, are examined in the light of turbulence models. The near-bottom boundary layers and equatorial turbulence, with their specific problems are the subject of two chapters.
In Part V, results from field experiments in coastal waters, estuaries, fjords and lakes illustrate the turbulence characteristics present in the mixing processes taking place in these environments, due mainly to tidal or wind stress forcing.
In nearshore regions or in shelf-seas, the water is sufficiently shallow for surface wave currents to reach the bottom and add to turbulence. Part VI presents case-studies of observations and modelling of turbulence associated with different shelf-sea regimes and also of internal wave contribution to shelf mixing.
The interaction of the large-scale quasi-2D turbulent flows with 3D dissipative turbulent structures is the main subject of Part VII, emphasizing the role of laboratory experiments complemented by numerical modelling. It presents a survey of large-scale flows, focusing on the aspects related to turbulence, mixing and diffusion, and describes the properties of geostrophic eddies and their role in large-scale ocean dynamics.
Finally, Part VIII presents information on the selected datasets that are included in the accompanying CD-ROM, which were obtained from measurement campaigns and numerical experiments with turbulence models.
In an overall view of the book with its 630 pages, we must say that it is a must for those already acquainted with turbulence theory and modelling, opening up broad perspectives of the state-of-the-art of marine turbulence. However, those taking their first steps in this difficult theme, will find most of the book’s content too hard without previous knowledge.
Global Warming the Complete Briefing—Third Edition
The author of this book has attempted to give a complete briefing on global warming, a topic that can no longer be ignored by anyone who lives on planet Earth.
Sir John’s approach is to take the reader through a briefing that starts with posing the fundamental question “Is our climate changing?”. He gradually weaves through the many variables that impact our climate system in a clear, logical manner; keeping the mathematics, physics and other technical elements to a basic level and a bare minimum.
The material is extensive, ranging from a thorough explanation of greenhouse gases, through their effects on our long-term climate; especially if emissions continue unabated in the future. The author draws comparisons between past and present climates such that the reader can gain an appreciation of the rates of change in warming and cooling in the past through the present. He then moves to the area of climate modeling. Here, the author helps the reader to gain an appreciation of the complexities of computer models, the importance of the ocean/land/atmosphere coupling and the feedback processes existing within the climate system. Future challenges to global climate modelling are considered, especially when moving beyond the dynamics and physics of climate models to incorporate elements like chemistry and biology of the biosphere. These models are very important when the author looks at climate change during this 21st century, as they play a major role in modelling impacts of future emission projections at regional and global levels.
The book looks extensively at the possible impacts of climate change on a wide range of socio-economic sectors and why we should all be concerned. However, the author also highlights the uncertainties that surround the issue of climate change and acquaints the reader with some of the perspectives within the scientific community. This section is especially useful for policy-makers, since they are charged with incorporating impacts of climate change on the sustainable development of their respective nations.
As the reader progresses through this text, he/she will find complete chapters that cover topics such as strategies to slow and stabilize climate change. Here, the writer proffers the use of internationally agreed high-level, global conventions and protocols to guide nations, at little or no cost, in slowing or stabilizing climate change. Future forms of alternative energy and transport that will make for a cleaner atmosphere and environment are discussed at length. The reader’s attention is drawn to the fact that continued emissions will add to unacceptable climate change but that, while the technology for renewable energy is now available, policy-makers will need to have appropriate incentives in place to encourage the development of alternative energy. However, the technology must be available to all countries.
The author closes this book with a relevant chapter “The global village”, which emphasizes that global warming is a long-term global issue and no nation is immune to its effects. However, although we all may contribute to this problem, its impacts will not be uniform and developing countries may be the ones to experience the greatest damage. Tackling the problem will require transcending national boundaries, as there will be a need for international action. Finally, having looked at what can be done at the global to national levels, the writer offers some recommendations for individual actions that can help to mitigate problems associated with global warming.
This book is truly worth readingfor an objective view on the subject of global warming and climate change. The wide range of graphs, tables and pictures complement the written material, making the text easy to read and the subject matter quite comprehensible.This mainly qualitative presentation makes this book an ideal text for a wide audience and I would recommend it as a useful reference at the secondary and tertiary levels of education for students of meteorology and related disciplines.
|Short printable version English|
|50 years ago...|
|International Polar Year|