Global Energy and Water Cycles

Edited by:
  • K. A. Browning &
  • R. J. Gurney
Cambridge University Press: 1999. 292pp. £50, $95

The interactions between energy and water cycles are basic to both weather forecasting and climate-change prediction. This book builds on a 1994 conference of the Global Energy and Water Cycle Experiment and attempts to assess our understanding of this interaction for forecasting on both short and long timescales.

Almost all of the relevant processes involved in the water and energy cycle (with the notable exception of sea ice) have their own subsections in the book. These include such diverse fields as numerical schemes for water-vapour advection, cloud physics, the movement of water through the soil and the ocean's response to fresh water. Each section presents cutting-edge science, emphasizes uncertainties and projects what future research is needed and likely.

The book focuses on how a process works and how it can be modelled, especially in the global general circulation models used to predict climate change. The problems are immense. To model the process, we must first understand it, which means we must be able to observe it. Observations of many hydrological processes are quite poor. Using available data, modellers have provided detailed representations of particular processes, with the relevant physics often occurring on very small scales. Whether these processes can be accurately simulated in terms of the larger-scale variables used in general circulation models, what level of detail is needed to make global models useful, and how representations can be made consistent among the different processes are three main themes in this book.

While the level of presentation is quite high, there is no attempt to make the coverage systematic. For example, there is no figure showing the climatological global precipitation field, as uncertain as it is.

This book is most appropriate for researchers and advanced graduate students, since it will update them on the diverse components involved in climate modelling. But state-of-the-art books in rapidly developing fields have a relatively short shelf-life. Significant developments have already occurred in the three years since most of these articles were written. For example, we have seen the launch of the Tropical Rainfall Measurement Mission and a moisture-conserving form of the semi-Lagrangian scheme for water-vapour advection has been developed. I estimate that another such book will be needed in around five years. With luck, the editors will consider making this a series.