The review below appeared in Physics Today, Volume 53, Number 11, p. 57, November, 2000.
Lazaros Oreopoulos and Steven Platnick
NASA/Goddard Space Flight Center
Gary E. Thomas and Knut Stamnes
Cambridge U.P., New York, 1999.
517 pp. $85.00 hc
The transfer of solar and thermal radiation within a coupled atmosphere-surface system is of fundamental importance in Earth and planetary sciences. Applications include energetics and climate modeling as well as remote sensing and photochemistry. Despite its critical role, radiative transfer is often found to be a relatively frustrating field for students. This may be due, in part, to the lack of good introductory texts and the many disciplinary backgrounds of students in Earth science programs (physics, chemistry, engineering, meteorology, and the like).
The new offering by Gary Thomas and Knut Stamnes, Radiative Transfer in the Atmosphere and Ocean, is the culmination of the authors’ teaching efforts over many years. It is a welcome addition to the small number of existing alternatives concerned with radiative transfer fundamentals and tools. The text is intended for advanced undergraduates and beginning graduate students in atmospheric and oceanic sciences, but it also provides a useful reference for the practitioner. Our review draws on our involvement in the development of a graduate course for which the book served as the main text.
A strength of the book is its early effort to emphasize the fundamental physics and underlying radiative interactions and to provide useful insight. It uses the classical Lorentz theory for describing molecular scattering and line shapes, and it describes nicely quantum mechanical considerations pertinent to molecular absorption. These discussions are not intended to be for detailed descriptions (as, for instance, is Atmospheric Radiation: Theoretical Basis by Richard M. Goody and Yuk L. Yung, Oxford 1989). The same can be said of the brief introduction to Mie (spherical particle) scattering; other texts can be consulted for the full mathematical derivation. Polarization is not discussed.
The intuitive fashion in which the various incarnations of the radiative transfer equation and its solutions are developed is another strength. Chapter 7 is a thorough treatment of the two-stream approximation and examines a large number of special cases. Chapter 8, on “accurate” numerical techniques, emphasizes the discrete ordinate method and follows nicely from the two-stream discussion. One may argue, however, that the 40-page presentation is at the expense of other methods that are arguably more intuitive and also widely used. These include, for instance adding/doubling, successive orders of scattering, and Monte Carlo methods. Although both chapters are rich in numerical detail, the unsophisticated reader would benefit from additional instructive examples and figures. For instance, a summary of radiance and flux dependencies on optical thickness, particle absorption, and solar geometry would have been valuable.
We appreciated the clear review of climate issues and the summary of radiative transfer concepts for climate applications presented in the last two chapters. Two details that drew our attention in these chapters were the summary plots of atmospheric absorption spectra in chapter 11, usually presented much earlier in books of this type, and the exclusive use of the term “greenhouse effect” in chapter 12 for a mathematical quantity.
A major concern is the book’s seemingly awkward organization. In particular, some theoretical details are delayed until later chapters on applications. For example, a student introduced to the fundamentals of absorption in chapter 4 might logically proceed to single-line transmission and band models (including k-distributions), rather than postponing the discussion until chapter 10. Other organizational difficulties include the apparent lack of a unifying theme in chapters 5 and 6 (somewhat abstractly titled “Principles of Radiative Transfer” and “Formulation of Radiative Transfer Problems,” respectively.) Topics in chapter 5 range from the definition of bidirectional reflectance to the radiative transfer equation solution in the absence of scattering; topics in chapter 6 range from scaling transformations for anisotropic scattering to the principle of reciprocity.
Another concern is notation. The authors follow the uncommon conventions of H.C. van de Hulst (Multiple Light Scattering, Academic, 1980), but they also make unorthodox choices for subscripts and superscripts (for example, the direct solar beam is indicated with a superscript s, although the corresponding angles use the common subscript 0 notation). Especially disconcerting is the common notation shared by numerous reflection and transmission functions, whose meanings (and units) depend on the arguments.
We had mixed feelings about the problem sets. They are more extensive than in previous texts but are often too challenging without adding much insight. More introductory problems would have been helpful.
All in all, this is a valuable resource for those interested in terrestrial radiative transfer. It contains good discussions and physical explanations within the main text, useful summaries, notes, comments, and up-to-date references. Prospective instructors should be aware that the extensive amount of material in the book makes it appropriate for a two-semester course.