Introduction and comments on books

Global Physical Climatology (Hartmann)

This is the textbook that ovarlaps best with what I want to talk in my class of earth science. It is not accidental. The author took Ph.D. at Princeton University, and I am myself much influenced by (guest lectures of) Dr. Syukuro MANABE and (lecture notes of) Dr. Abraham OORT who taught there.

The subject is the science of the global atmosphere and hydrosphere in a physical perspective. In this perspective, though not by necessity but by limitation of a capacity of any expert, we do not consider variety of constituents as in chemical or biological perspectives. For example, it is often assumed that the atmosphere consists of "dry air" and water vapor, and the ocean consists of water and "salt". But we do consider spatial inhomogeneity.

Since SELLERS (1965) or even earlier, the term "physical climatology" is often considered as a synonym of "heat balance climatology", and this book can also be categorized as such. But what SELLERS mainly discussed was energy balance at the surface of the earth. It was largely a two-dimensional perspective. On the other hand, HARTMANN has more emphasis on the three-dimensional distribution of energy balance in the atmosphere.

This book consists of the chapters:

  1. The climate system
  2. Global energy balance
  3. Atmospheric radiative transfer and climate
  4. Energy balance of the surface
  5. Hydrologic cycle
  6. Atmospheric general circulation
  7. Ocean general circulation
  8. History and evolution of earth's climate
  9. Climate sensitivity and feedback mechanisms
  10. Global climate models
  11. Natural climate change
  12. Anthropogenic climate change.

At the University of Washington, the author gives two lecture courses using this textbook. The first half (Chapters 1-7) introduces the actors, and in the second half (Chapter 8-12) they interact. What is really interesting is the second half, but understanding of the first half is prerequisite. When I taught at a department of geography, it took a semester to cover just the first half, even though I skipped relatively difficult part of radiative processes (Chapter 3).

It seems that the expertise of the author is the most evident in "climate sensitivity and feedback mechanisms" (Chapter 9). He is active in this field (e.g. HARTMANN and MICHELSEN 2002). To fully understand it, Chapter 3 is also important.

On the other hand, it seems that the author heavily relied on other textbooks about the subjects of energy balance at the surface and of water cycle (Chapters 4-5). The examples are mostly the cases of North America. Though, of course, the number of examples cannot be indefinitely large, I think that a better perspective can be gained by comparing situations of Asia as well. It seems that the standard textbooks of these subjects (in English) are still SELLERS (1965) and BUDYKO (1971). There have been significant advance since these books appeared, however, and Hartmann's book helps partial update of the knowledge.

In the context of energy balance, there are two regrettable points in the way of description of this book. The first one is about the definition of atmospheric energy balance. The equation 6.1 is the energy balance of the "dry atmosphere". Energy associated with water vapor is excluded. In the discussion of horizontal energy transport by the atmosphere in Section 2.9 and Section 6.3.9, energy transport associated with water vapor transport is included. Both discussions are valid, but, in my opinion, it is necesary to explain the difference of viewpoints more clearly. More complete description of the atmospheric energy balance is found in PEIXOTO and OORT (1992).

Another similar problem is about the definition of surface energy balance. One formulation is to discuss energy of a finite layer, typically a few meters thick for land and 100 m thick for ocean. Another formulation is to discuss the continuity of energy fluxes at the surface. This can be regarded as a limit of finite-layer energy balance by making the thickness of the layer infinitesimally small. Again both formulations are valid, but the presentation in the book (in particular, Equation 4.1) is somewhat amgibuous about the choice of the viewpoints.


2004-Nov-25; Moved here 2009-Feb-09; revised 2010-Dec-31
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