The Global Circulation of the Atmosphere - Hardcover

Hardcover

ISBN 10: 0691121818 ISBN 13: 9780691121819

Verlag: Princeton University Press, 2007

Inhaltsangabe

Despite major advances in the observation and numerical simulation of the atmosphere, basic features of the Earth's climate remain poorly understood. Integrating the available data and computational resources to improve our understanding of the global circulation of the atmosphere remains a challenge. Theory must play a critical role in meeting this challenge. This book provides an authoritative summary of the state of the art on this front.

Bringing together sixteen of the field's leading experts to address those aspects of the global circulation of the atmosphere most relevant to climate, the book brings the reader up to date on the key frontiers in general circulation theory-including the nonlinear and turbulent global-scale dynamics that determine fundamental aspects of the Earth's climate. While emphasizing theory, as expressed through relatively simple mathematical models, it also draws connections to simulations with comprehensive general circulation models. Topics include the dynamics of storm tracks, interactions between wave dynamics and the hydrological cycle, monsoons, tropical and extratropical dynamics and interactions, and the processes controlling atmospheric humidity.

An essential resource for graduate students in atmospheric, ocean, and climate sciences and for researchers seeking an overview of the field, The Global Circulation of the Atmosphere sets the standard for future research in a science that stands at a critical juncture.

With a foreword by Edward Lorenz, the book includes chapters by Christopher Bretherton; Kerry Emanuel; Isaac Held; David Neelin; Raymond Pierrehumbert, Hélène Brogniez, and Rémy Roca; Alan Plumb; Walter Robinson; Tapio Schneider; Richard Seager and David Battisti; Adam Sobel; Kyle Swanson; and Pablo Zurita-Gotor and Richard Lindzen.

Über diesen Titel

Über die Autorin bzw. den Autor

Tapio Schneider is assistant professor of environmental science and engineering at the California Institute of Technology. Adam H. Sobel is associate professor of applied physics and applied mathematics and of earth and environmental sciences at Columbia University.

Von der hinteren Coverseite

"This is an authoritative status report on the current theoretical understanding of the general circulation of the atmosphere, one that will be of value for many years to come."--John M. Wallace, University of Washington

"This is a terrific collection of articles. The authors, all authorities in their respective subfields, provide a diverse and insightful view of the general circulation of the atmosphere, and the book as a whole makes a unique and valuable contribution to the field. It can be used profitably by graduate students and by scientists as a general resource; furthermore, journal clubs can find here a ready-made curriculum."--Geoffrey Vallis, Geophysical Fluid Dynamics Laboratory and Princeton University

Aus dem Klappentext

"This is an authoritative status report on the current theoretical understanding of the general circulation of the atmosphere, one that will be of value for many years to come."--John M. Wallace, University of Washington

"This is a terrific collection of articles. The authors, all authorities in their respective subfields, provide a diverse and insightful view of the general circulation of the atmosphere, and the book as a whole makes a unique and valuable contribution to the field. It can be used profitably by graduate students and by scientists as a general resource; furthermore, journal clubs can find here a ready-made curriculum."--Geoffrey Vallis, Geophysical Fluid Dynamics Laboratory and Princeton University

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The Global Circulation of the Atmosphere

Princeton University Press

Copyright © 2007 Princeton University Press
All right reserved.
ISBN: 978-0-691-12181-9

Chapter One

Progress and Problems in Large-Scale Atmospheric Dynamics Isaac M. Held

1.1. Introduction

A theory for the general circulation of the atmosphere has at its core a theory for the quasi-horizontal eddy fluxes of energy, angular momentum, and water vapor by the macro-turbulence of the troposphere, as well as a theory for the much smaller-scale convective motions that transport heat and water vertically, especially in the Tropics. A few of the many issues related to convective vertical fluxes are discussed in chapters 7,8, 10, and 11 in this volume. The focus in this chapter, and of chapters 2-6, 9, and 12, is primarily on the large-scale quasi-horizontal component of the problem. In the Tropics, fluxes by large-and small-scale eddies are so tightly coupled that one cannot easily discuss one without simultaneously discussing the other. But outside of the Tropics, one can hope that a focus on large-scale dynamics in isolation is a meaningful starting point, and it is on the extratropical circulation that I concentrate here.

All of us would love to find a simple variational principle or "fundamental theorem of climate" that solves this problem in a single stroke, but I suspect that most of us are skeptical that such a principle exists. We assume, instead, that the best way of developing theories for a system of this complexity is to construct a hierarchy of models, of varying levels of comprehensiveness, chosen so as to capture the essential sources of complexity with minimal extraneous detail. When confronted with a theory claiming great generality, we expect to see a demonstration that it explains the behavior seen on a number of different levels of our model hierarchy.

An analogy with the use of "model organisms" in biology is informative. Nature has provided us with just the kind of hierarchy, from bacteria to fruit fly to mouse, needed to build up an understanding of our own complex biology. We have no such ready-made hierarchy in climate research, and must instead design and build our own. See Held (2005) for an extended discussion of this analogy and the consequences of the fact that our climate hierarchy is a theoretical construct while the biological hierarchy is provided by nature.

What hierarchy of models should we study so as to best understand how global climate is controlled by external parameters and boundary conditions? The choice of models is centrally important. Only if, as a community, we have selected appropriate models to study collectively will our understanding accumulate efficiently. I personally do not feel that appropriate models can be selected in a systematic way; our physical intuition must guide us towards the most informative models.

In this chapter I will refer to the classic two-layer quasigeostrophic (QG) model, moist QG models, and particular idealized dry and moist primitive-equation models on the sphere. The discussion revolves around the related problems of the poleward eddy heat flux, the effect of latent heat release on midlatitude eddies, and distinctions between the dynamics of the upper and lower troposphere. Considerable space is devoted to the simplest of these models, the two-layer QG model, in an especially simple horizontally homogeneous configuration.

I find this model of homogeneous QG turbulence useful from several perspectives, but there is no claim that the theory for the eddy fluxes in this model is of direct quantitative relevance to the atmosphere. When we talk about the need for a model hierarchy, we are implicitly assuming that the more idealized members of this hierarchy are missing some important ingredients, but that, in spite of these limitations, an understanding of these simpler models is a useful stepping stone to an understanding of their more complex relatives.

1.2. The Two-Layer QG Model

The two-layer QG system provides us with what maybe our simplest turbulent "climate" model. The state of this model is determined by the stream functions for the non-divergent component of the horizontal flow in two layers of fluid, meant to represent the flow in the upper ([[psi].sub.1]) and lower([[psi].sub.2]) troposphere, the (eastward, northward) components of the velocity being (u, v)=(-[partial derivative][psi]/[partial derivative]y, [partial derivative][psi]/[partial derivative]x). In the meteorological context we can think of two isentropic layers of ideal gas with different entropies, or potential temperatures [theta], with [[theta].sub.1]>[[theta].sub.2] so as to represent a gravitationally stable system. Hydrostatic and geostrophic balance combine to create Margules' relation between the perturbations to the height of the interface between the two layers, [eta], and the difference between the two streamfunctions. In a Boussinesq fluid (with all potential temperatures assumed to be small perturbations away from a constant [[theta].sub.0]) this relation is f([psi].sub.1]-[[psi].sub.2])=-[g.sup.*] [eta], where [g.sup.*] [equivalent to] g([[theta].sub.1]-[[theta].sub.2])/[[theta].sub.0] is the reduced gravity and f the Coriolis parameter. The dynamics reduces to the advection by these non-divergent flows of a scalar, the QG potential vorticity [q.sub.k], within each layer, where

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] [1.1]

and [lambda] is the radius of deformation, defined by [[lambda].sup.2] = [g.sup.*]H/[f.sup.2],with H the resting depth of the two layers (assumed to be equal here). The final term in (1.1), with a constant, is an approximation to the all-important vorticity gradient due to the increase in the radial component of the vorticity of solid body rotation with increasing latitude y. When relating this two-layer picture to a continuously stratified atmosphere, we think of [([g.sup.*]H).sup.1/2] [right arrow] NH, with [N.sup.2] = (g/[theta])[partial derivative][theta]/[partial derivative]z and -[eta] as proportional to the vertically averaged potential temperature.

A simple way of creating a statistically steady state is to force the system with mass exchange between the two layers, this model's version of radiative heating, arranged so as to relax the interface to a "radiative equilibrium" shape with a zonally symmetric meridional slope. This mass exchange can be expressed in terms of potential vorticity sources in the two layers. One also invariably includes two types of dissipation: small-scale diffusion is needed to mop up the vorticity variance that cascades to small scales; and surface friction, damping the low-level vorticity, is needed to remove energy in a non-scale selective manner. Energy does not cascade to small scales in this model and cannot be removed realistically with horizontal diffusion.

Radiative equilibrium is a solution of these equations, with no flow in the lower layer and zonal flow in the upper layer, with the Coriolis force acting on the vertical shear U = [u.sub.1] - [u.sub.2] between the two layers balancing the pressure gradients created by the radiative equilibrium interface slope. This flow is unstable in the absence of the dissipative terms, when the isentropic slope is large enough to overcome and reverse the sign of the north-south potential vorticity gradient in one of the layers. In flows with temperature decreasing...

Details zur Ausgabe

• Verlag: Princeton University Press
• Erscheinungsdatum: 2007
• Sprache: Englisch
• ISBN 10: 0691121818
• ISBN 13: 9780691121819
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 385
• Herausgeber: Schneider Tapio, Sobel Adam H.
• Kontakt zum Hersteller: Princeton University Press; https://press.princeton.edu/books; ; 7th Floor, New South Building; PRINCETON; NJ; 8544; USA
• Verantwortliche Person: Nicht verfügbar