The determination of geophysical parameters from space

The determination of geophysical parameters from space

Pergamon All nghts PII: S1364-6826(96)00177-0 reserved. Prmted ,n Great Bntan 136468261’97 $17.00+000 Book Reviews Physics of the Aurora and Airgl...

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Pergamon

All nghts

PII: S1364-6826(96)00177-0

reserved. Prmted ,n Great Bntan 136468261’97 $17.00+000

Book Reviews Physics of the Aurora and Airglow, Chamberlain J. W., 1995, 704pp., Classics in Geophysics, Volume 1, AGU, $55.00 ($38.50 AGU member price) pb, ISBN o-87590-857-8. The American Geophysical Union has instituted a new book series called Classics in Geophysics, and this is the first of the series. It is a reprint of the renowned book which was originally published in 1961. The first two chapters cover the fundamental physics of spectral line radiation, and the scattering of radiation and radiative transfer theory which do not change on a time scale of a third of a century. Some errata are pointed out, using a bold arrow in the margin, and the corrections are listed at the start of the book. Chapter 3 gives background information (using c.g.s. units) on a dipole magnetic field, the geomagnetic field, charged particle motions, electromagnetic wave propagation in a plasma (with frequencies in Mc/sec), Chapman theory of an ionospheric layer, model atmospheres and the thermosphere. Detailed books have been written on each of these topics, and it is only the last section which appears very dated. Nowadays, much is known about the occurrence of aurorae in space and time which is the topic of Chapter 4 (with Information derived from ground-based observations, and with black and white photographs). Chapter 5 on amoral spectroscopy and photometry, is still a valuable compendium. The radio-aurora (Chapter 6) is a term which has rather gone out of use, to be replaced by radar studies --with the equipment having a diversity of acronyms. The discussion of physical processes in the aurora1 atmosphere (Chapter 7) due to proton and electron bombardment is still useful. It is on topics discussed in the second half of the book (charged particles in space, hydrogen emissions in nightglow, emission height, airglow mechanisms) that current research is going in new directions. using satellite observations and computer modelling and simulation techniques of plasma phenomena. At the start of the book, there are four pages of notes, referring to books and papers published since 1961, and to more recent papers by the author himself. This is a good book giving background information for a new researcher in observations of the aurora or airglow.

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M. J. Rycroft Space University France

The Aurora: SutvEarth Interactions, Bone N., 1996, 172pp., John Wiley & Sons Ltd, Wiley-Praxis Series in Astronomy and Astrophysics, Second Edition, E19.99 pb, ISBN O-471. 96024- 1. In comparison with Chamberlain’s academic tome, this book is a chatty introduction to the subject of the aurora which is put in the context of solar-terrestrial physics and space weather. It benefits from sixteen colour photographs taken

by members of the British Astronomical Association (Aurora Section), including the author. This is a book to whet the appetite of aurora1 observers by explaining, at a popular level, what the aurora is, what causes it and why studies of it are relevant to humanity. Mentions are made of aurora1 activity throughout history as portents of doom, the great aurorae of 13 and I4 March, 1989, and of 8 and 9 November, 1991, and of ways of investigating aurorae since the seventeenth century, culminating in the International Geophysical Year (1957 to 1958) and space age studies. Chapter 4 considers the active Sun, mentioning helioseismology and coronal mass ejections. The behaviour of the Earth’s magnetosphere is outlined in Chapter 5, and other planetary magnetospheres are introduced. Chapter 6 discusses the properties of the atmosphere and ionosphere at heights where aurorae are produced, and the atomic processes which explain them. Aurorae observed at midlatitudes and schemes for recording them visually are covered in Chapter 7. Chapter 8 discusses effects associated with aurorae such as geomagnetic field changes, Forbush decreases and radio phenomena; Chapter 9 is on noctilucent clouds. This is a valuable book for its intended audience. introducing the physics of what lies behind aurora1 observations.

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M. J. Rycroft Space University France

The Determination of Geophysical Parameters from Space, Fancey N. E., Gardiner I. D. and Vaughan R. A., (eds), l996,364pp., Scottish Universties Summer School in Physics &Institute of Physics Publishing, &105.00, $210.00 hb. ISBN 0-7503-O-350-6 This valuable book arises from a NATO Advanced Study Institute held, as the 43rd Scottish Universities Summer School in Physics, in Dundee in August and September 1994. It covers remote sensing of the Earth’s land and sea surface, the atmosphere and air-sea interactions, primarily using spaceborne instruments. The book’s sixteen chapters are written by different authors, The first chapter overviews the current status of satellite remote-sensing-the physics, data sets, international programmes, data centres and future missions-all in 15 pages. Current European initiatives are explained in more detail, as are the activities of the Natural Resource Institute of Britain’s Overseas Development Organisation, especially those in Africa, in the next two chapters. Synthetic aperture radar principles and applications are well reviewed by J. Askne (of Chalmers University of Technology, Sweden, in 58 pages), and then applied to the automatic detection of oil spills. Radar altimetry basics, and applications to ocean wave phenomena, to the cryosphere and to desert regions, are well covered by D. Martripp

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(MSSL, U.K., in 68 pages). Water quality research is also reviewed. Derivation of the Earth’s surface temperature, for use in atmospheric general circulation models, is covered by Y Xue and A. P. Crackwell (University of Dundee, U.K., in 32 pages). The mathematics of retrieving atmospheric parameters, especially for the Microwave Limb Sounder on UARS, is the topic of G. E. Peckham and I. H. Woodhouse (Heriott-Watt University, U.K., in 12 pages). Ozone observations, and the effects of reduced ozone amounts, are reviewed by C. Varotsos (University of Athens, Greece, in 22 pages), with C. G. Helmis, from the same University. contributing a short chapter on acoustic sounding of the atmosphere. The last four chapters are concerned with ways of dealing with digital data. Data stored on CD-ROMs can be retrieved to create animated meteorological images for training. Successive images, or sequences of images, can be analysed either by the functional analytic method or by the maximum cross correlation method to determine displacement vector fields such as sea surface currents or winds in the atmosphere.

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M. J. Rycroft Space University France

The Mount Pinatubo Eruptions, Effects of the Atmosphere and Climate, Fiocco G., Fua D. and Visconti G., 1996, 31Opp., NATO ASI Series, Series I: Global Environmental Change, Vol. 42, Springer-Verlag, Berlin, DM 180.00 hb, ISBN 3540-61281-5. The Mount Pinatubo volcanic eruption which occurred on 15 and 16 June 1991 hit the headlines around the world. Here its effects on the atmosphere and climate, as reported at a NATO Advanced Research Workshop held in Rome at the end of September 1994, are presented.

The results of this global-scale experiment are considered in four sections, each of which has several chapters, and with many scientists contributing. The first section is on characterising the volcanic aerosol (sulphur dioxide) cloud, injected into the lower stratosphere, using ground-based lidar observations, airborne measurements and the ISAMS instruments aboard UARS. The cloud from Mount Pinatubo dispersed to the west, encircling the Earth after three weeks. About 6 months later, the cloud had reached high latitudes in both hemispheres. The decay of the aerosol cloud with time is well measured by lidars at different locations. The ISAMS observations are interpreted to give the Mt Pinatubo aerosol cloud density as - 10.’ m’ / km’, and the effective particle radius of 0.6 mm. Between 100 and 5 hPa (mb), there was almost 20 megatonnes of sulphuric acid at the start of 1992, which reduced to 15 megatonnes six months later. The second section is concerned with the induced temperature changes. The warming in the lower stratosphere is - 1°C with -0.2”C reduction of the global mean temperature of the troposphere from mid 1992 to mid 1993. The effects on ozone in the stratosphere are considered in the third section. Over Europe, the largest effect, a 30% ozone reduction at 17 km altitude, was found early in 1993. The maximum decrease of the total column of ozone was typically - 5%. Changes in the polar regions were also observed and these are discussed too. Finally, the effects on climate are considered. The enhanced aerosol layers absorb the upcoming terrestrial radiation, and are warmed. Scattering of solar radiation from the aerosols enhances the Earth’s albedo, and contributes to the global cooling. However, because of many feedback processes in the Earth’s climatic system, the situation is very complex. More sophisticated models are required.

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M. J. Rycroft Space University France