August  2006 Downloads & Links

In the press

Book reviews

Atmospheric Turbulence and Mesoscale Meteorology
E. Fedorovich, R. Rotunno and B. Stevens (Eds.). 
Cambridge University Press (2004). 
ISBN 0-521-83588-7 (h/b).
x + 280 pp.
Price: £70/US$ 120.

This book brings together leading researchers to discuss the developments in the fields of atmospheric turbulence and mesoscale with emphasis on the areas pioneered by Douglas K. Lilly.

The authors start with the frustration of the turbulence community in the early 1960s. Kolmogorov accepted that his turbulence theory had some defect that needed a change in the exponent in the turbulent spectrum and Lilly cited the difficulties encountered due to there being no real unifying theory relating results from one experimental geometry to another.

Lilly proposed the large-eddy simulation (LES) approach and later determined the sub-grid model constants that helped overcome the difficulties encountered in the experimental turbulence research work over sites of differing geometries. Today, LES is a dominant tool in turbulence research. Most experiments in small-scale meteorology are numerical ones through direct numerical simulation of all scales of motion in turbulent flow.

Lilly suggested that the interactions of turbulence, radiation and phase changes were tightly coupled on small small space- and time-scales. The authors opine that, in its sophisticated coupling of radiative, turbulent, and microphysical processes, Lilly’s work was at least 35 years ahead of its time.

LES provides scientists with an invaluable tool in their efforts to unravel the mysteries of flows beyond the reach of laboratories. Comparisons between simulations and observed cloud evolution suggest that simulations perform reasonably well and suggest the use of LES for multi-scale flows.

In the chapter on model numerics for convective-storm simulation, the author notes that the advances made in this area have been feasible owing to the enormous growth in computing power, advancements in model numerics, physical parametrization and data analysis in order to capture the complexity of atmospheric convection.

The Weather  Research and Forecasting model, which has the skill to produce realistic forecasts of precipitation and kinetic energy spectra across a broad range of scales, resulted from the challenge posed by Lilly to the convective-storm research community.

In a discussion of the difficulties in operational numerical weather prediction (NWP) for the mesoscale, the  author recommends that, given that most weather systems on the convective scale are driven by highly local effects, it is probably most economical to conduct the convective-scale NWP and its data assimilation in a distributed and “on demand” manner, i.e. local forecast offices guide the execution of their own customized version of the unified model.

In a review of the history of research on the energy cycle and structure of tropical cyclones, the author concludes that tropical cyclones are highly susceptible to small ocean cooling under their eye walls and the associated radial profile of pressure and wind in this region and  has derived a valid wind profile that depends explicitly on environmental parameters.

Four subjects related to the influence of mountains on regional climates are introduced: flow splitting and wave breaking; mountain lapse rates; orographic precipitation and wave drag. These subjects have been studied using reductionist methods of physics but now must also be tackled using numerical modelling methods.

In a review of the spectrum of mesoscale atmospheric variability and its dynamic causes, the main emphasis is placed on the developments surrounding the work of Lilly on the concept of stratified turbulence. Studies on stratified turbulence based on laboratory work and on numerical simulations are also discussed. The  conclusion is that stratified turbulence plays a more significant role in the atmosphere than in the ocean. The authors suggest that research work on atmospheric mesoscale variability and stratified turbulence needs to be intensified to resolve the observed discrepancy in the modelling results of atmospheric circulation.

This book is a must for research workers in the field of turbulence and mesoscale meteorology. The use of large-eddy simulation, especially in understanding the processes that cause marine subtropical Stratocumulus clouds to break up into shallow Cumuli, will assist in climate research over large regions and thus improve the way general circulation models simulate these clouds. Also, meso-scale variability is taking on renewed importance because of the need to specify error fields for assimilation of meteorological data into numerical models.

Indeed, researchers and graduate students, working in the lower atmospheric motion scales (mesoscales and lower), will find this book  an excellent resource for developing tools and using them to analyse and predict atmospheric phenomena on the mesoscale and lower space-scales.

Raphael E. Okoola


Primer on climate change and sustainable development—facts, policy
analysis and applications

Mohan Munasinghe and Rob Swart.
Cambridge University Press (2005). 
ISBN 0-521-00888-3. xii + 445 pp.
Price: £30.

An absorbing text attempts to bring “climate change” from the domain of scientific enquiry and research to a domain which is of concern and interest to people, governments and policy makers. One of the greatest paradoxes of the present times is that there are too many poor in a world of unprecedented prosperity.  The authors aim to address this issues from the perspective of climate change. 

The authors explain long-term climate-change projections and related emission scenarios.  Future emission projections are dependent on complex factors such as population growth and technological, social and economic development.  This lays the foundation of links between climate change and development.

The idea of “making development more sustainable” is introduced.  Life style, consumption patterns, depletion and degradation of natural resources are all key elements in the concept.  The impacts of climate change and vulnerability are also to be considered in making economic decisions linked with climate change.

The relation between emissions related to human activities is a function of population technology and governance.  Thus, emission-mitigation efforts are important in deciding the road map for sustainable development.  Mitigation and adaptation are equally important but need different scales of effort.  Controlling emissions is a global effort, while adaptation is more at a local/regional level. 

Water stress due to climate change will increase with rising population.  Adaptation is basic to any future development plans in this sector.  Human health, energy and agriculture are the other sectors for which possible adaptation steps are discussed.  They include changing crop patterns, increasing drought toleration, seasonal forecasting, inter-basin transfer, desalinization, etc.  While these measures are costly,  lack of action is likely to magnify these costs in the future.

The authors argue that though specific impacts and adaptation strategies would vary, adaptive capacity must be strengthened substantially, especially in the poorest and most vulnerable regions and countries. They highlight the special problems of small island States which have low adaptive capacity, limited resources and poor infrastructure.

The cost of mitigating climate change is balanced against benefits of avoiding climate damage and incremental changes to the cost of adaptation.  A multi-criteria approach of cost benefit analysis is advocated instead of only monetary value.  The stabilization of emissions and long-term mitigation is a complex matter and needs to be addressed from various angles.  Pathways towards different levels of stabilization and associated costs are discussed.

The authors also present how the United Nations Framework Convention on Climate Change and the Kyoto protocol, which underpins the mitigation measures, are linked with sustainable development.  The authors believe that stabilization of greenhouse-gas concentrations would eventually need the participation of all regions in an emission control scheme. Clean development mechanisms, deforestation and carbon sequestration are important, while joint implementation and technology transfer would also contribute to controlling future emissions.  The cost of mitigation noptions in different sectors is considered.

It is necessary to understand how global warming and our development pathways are interlinked.  This book is a major contribution to climate-change-related issues in recent times and as such is a must for students, teachers, policy-makers and governmental authorities at local, regional and global levels.

U.S. De


New book received for review in the WMO Bulletin

Discrete Inverse and State Estimation Problems: With Geophysical Fluid Applications
Carl I. Wunch. 
Cambridge University Press (2006). xi + 371pp.
ISBN 0-521-85424-5 (h/b),
Price: £70/US$ 125.

The problems of making inferences about the natural world from noisy observations and imperfect theories occur in almost all scientific disciplines. This book addresses these problems using examples taken from geophysical fluid dynamics. It focuses on discrete formulations, both static and time-varying, known variously as inverse, state estimation or data-assimilation problems. Starting with fundamental algebraic and statistical ideas, the book guides the reader through a range of inference tools, including the singular value decomposition, Gauss-Markov and minimum variance estimates, Kalman filters and related smoothers and adjoint (Lagrange multiplier) methods. The final chapters discuss a variety of practical applications to geophysical flow problems.




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