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Atmospheres in the Solar System:
Comparative Aeronomy Geophysical
Monograph Series Editors: Michael Mendillo, Andrew Nagy,
and J.H. Waite Published in 2002 |
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Preface Introduction I. Overviews 1 Aeronomic Systems on Planets, Moons, and Comets 2 Solar System Upper Atmospheres: Photochemistry, Energetics and
Dynamics 3 Solar System Ionospheres 4 Auroral Processes in the Solar System 5 Airglow Processes in Planetary Atmospheres II. Interactions Between Planetary and Small Body Atmospheres with the Surrounding Plasma Medium 1 Magnetosphere-Ionosphere Coupling at Earth, Jupiter, and Beyond 2 Comparison of Auroral Processes: Earth and Jupiter 3 Numerical Techniques Associated with Simulations of the Solar
Wind Interactions with Non Magnetized Bodies 4 Plasma Flow Past Cometary and Planetary Satellite Atmospheres III. Chemistry, Energetics and Dynamics 1 Wave Coupling in Terrestrial Planetary Atmospheres 2 Exospheres and Planetary Escape 3 Surface Boundary Layer Atmospheres 4 Solar Ultraviolet Variability Over Time Periods of Aeronomic
Interest 5 Meteoric Material - an Important Component of Planetary Atmospheres 6 Current Laboratory Experiments For Planetary Aeronomy IV. Models of Aeronomic Systems 1 Simulations of the Upper Atmospheres of the Terrestrial Planets 2 Thermospheric General Circulation Models for the Giant Planets:
The Jupiter Case 3 Ionospheric Models for Earth 4 The Application of General Circulation Models to the Atmospheres
of Terrestrial-Type Moons of the Giant Planets 5 The Extreme Ultraviolet Airglow of N2 Atmospheres V. Observational Applications 1 The Application of Terrestrial Aeronomy Groundbased Instruments
to Planetary Studies 2 Ultraviolet Remote Sensing Techniques for Planetary Aeronomy 3 Mass Spectrometry for Future Aeronomy Missions VI. Atmospheres of Other Worlds 1 A Possible Aeronomy of Extrasolar Terrestrial Planets 2 Can Conditions For Life Be Inferred From Optical Emissions of
Extra-Solar-System Planets? Atmospheres are crucial components of our universe. They are the only observable regions of stars and giant planets, both within and beyond our solar system. Some terrestrial-size bodies (Venus, Earth, Mars, Titan and Triton) have permanent atmospheres while others (e.g., Mercury, Moon, Io, and Europa) have tenuous gaseous envelopes that change daily. Comets are tiny bodies by planetary yardsticks, but their atmospheres can be the largest visible objects in the night sky. Atmospheric science strives to understand how such a diverse set of atmospheres form, evolve and disappear. Our current understanding of the mystery of life links atmospheres to biology via such terms as "biosphere" and "astrobiology." But even aside from the question of life beyond Earth, the study of solar system atmospheres is, in its own right, an exciting and exploration-rich field of modern space science. The origin of this monograph is based on that fact. While the laws of physics are the same for each member of the solar system, the chemical constituents are not, nor are their magnetic fields, or amount of energy received from the Sun. Within this context of diversity in solar system membership, the comparative-studies approach has emerged as the framework best suited to understanding the coupling, energetics and dynamics of multiple atmospheric systems. To avoid a mere survey of intrinsic characteristics, to move beyond classification nomenclature being a stand-in for progress, and to probe the depth and breadth of our understanding requires a timely and comprehensive approach to a rapidly changing field. We have addressed this need with an eye towards tutorial overviews and state-of-the-art descriptions for graduate students and young professionals drawn to aeronomy. We couple this to an agenda of synthesis for veterans in the field. Thus, the six sections of this monograph (each with multiple chapters) are so structured, and all contain an excellent set of references to enrich and guide additional research. The specific origin of this book derives from a series of workshops at the annual meeting on Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) held each summer in Boulder, Colorado. Comparative mesospheres, gravity wave signatures, aurora and airglow, and exospheres were the principle topics discussed over a several year period. From these workshops, a clear need emerged: a comprehensive meeting devoted exclusively to Comparative Aeronomy in the Solar System. With support from NASA and NSF and organizational expertise from the Southwest Research Institute (SwRI), a Yosemite Conference was held on 8-11 February 2000 on that topic. The current work incorporates the basic topics treated at Yosemite with additional invited contributions. In brief, we engaged the best possible set of authors to treat the core topics needed for the research fields of major current activity. Cross references by section and chapter designations bring a unity to the material presented. In addition to the authors' expertise and the development and careful preparation of their manuscripts, we acknowledge the valuable contributions of Ms. Cynthia Farmer and Dr. William Lewis of SwRI for organizing the Yosemite Meeting and Dr. Marina Galand (Boston University) and Dr. Steven Bougher (University of Arizona) for their co-convening of pre-cursor CEDAR workshops. Ms. Maria Stefanis O'Connell (Boston University) served as Editorial Assistant with care, devotion and competence, factors of crucial importance in assembling a monograph from author-produced copy. Similarly, we thank our AGU acquisitions editor, Allan Graubard, and production editor, Bethany Matsko for their expertise on a host of development and production details and schedules. Most importantly, we thank the referees for the chapters contained in this volume. With their generous contributions of time and thoughtful suggestions on content, the colleagues listed below truly share in the success of the chapters that follow. Several colleagues provided illustrations and images used on the cover and on the section heading pages, including J. Forbes (Section I), J. Spencer (Section II), I. Müller-Wodarg (Section IV), J. Clarke (Section V), and M. Mendillo (Frontispiece, Section III, Section VI). Finally, in recognition of her fundamental contributions to the field of comparative aeronomy, and in acknowledgement of her enthusiastic participation in the CEDAR Workshops and Yosemite meeting dedicated to these topics, we dedicate this volume to Dr. Jane Fox with best wishes for a continuing career of active research and professional service. Michael Mendillo Andrew Nagy and J. H. Waite Geophysical
Monograph Series Volume 130 Michael Mendillo Andrew Nagy and J. H. Waite When asked about the age of the solar system, the standard response
is to say that the Sun and planets formed about 4.6 billion years
ago. What this response fails to convey is a sense of continuity or,
perhaps better stated, of evolution from then to now. We have in the
membership of the solar system nine wonderful experiments in planet
formation, dozens of cases for moons, and countless asteroid and comet
scenarios. While we can say rather com-fortably that our Sun is a
"typical" main sequence star, we cannot point to a "typical"
planet. There is a lesson in that statement and a research challenge
of considerable complexity. This monograph deals with a central component
of this challenge, namely, to describe the basic structure and dynamics
of the upper atmospheres and ionospheres in our solar system and,
moreover, to understand their differences. Using the same format, Figure 2 gives the peak electron density and
its altitude for the ionosphere on each planet. Excluding Mercury's
weakly ionized component of a thin transient atmosphere, it is the
Earth that breaks the pattern. Again, composition (atomic vs. molecular
ions) matters! Finally, in Figure 3, the magnetic field strength,
orientation, and solar wind stand-off distance are given for the six
planets with intrinsic dipoles. The patterns of magnetic pressure
balancing solar wind kinetic energy density scale appropriately with
dipole strength and distance from the Sun, with the result of all
six ionospheres being well inside their planet's magnetopause. Magnetosphere-ionosphere-atmosphere
coupling is thus of fundamental importance for these cases. Does the
absence of auroral heating at Venus or Mars lead in any way to their
low neutral temperatures in Figure 1? In the chapters that follow, experts in aeronomy and in the fields that couple to it present up-to-date summaries of the major accomplishments and outstanding issues in the field. Tutorial reviews appear in Part I, with an emphasis on the basic principles underlying key systems. That each ionosphere/atmosphere encountered has important interactions with a surrounding plasma medium (solar wind or magnetospheric) is treated in Part II. The chemistry, energetics and dynamics of atmospheric systems are treated in Part III, and a description of modeling capabilities appears in Part IV. The roles of new observing techniques are described in Part V. Looking beyond our heliospheric members to the emerging field of extra-solar-system planets, Part VI concludes with views of worlds unseen.
Bougher, S. W., S. Engel, R. G. Roble, and B. Foster, Comparative
terrestrial planet thermospheres: 2. Solar cycle variation of global
structure and winds at solstices, J. Geophys., Res., 105, 18669-17692,
2000. |
Nb: If you are interested to get this volume, contact AGU (1800-966-2481 or orders at agu.org).
The order number is GM130-989-2. The book should be off press by May 24, 2002
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