The Magnetosphere, the high-latitude ionosphere, and their interactions

Book reviews The Magnetosphere, the High-latitude Ionosphere, and their Interactions, BEYN~N G. Sir. B~YII R. Sir. COWLEY S. W. H. and RY~KOFT M. J. (The Royal Society) (eds). 19x9. 25 I pp.. &50 (hb). Earth space plasma physics is passing through an interesting phase. With the dearth of fresh ‘in situ’ satellite data, scientists are focusing their efforts on alternative (remote sensing) techniques to gain a deeper understanding of Earth’s magnetised space plasma environment. One line of research seems particularly promising: the use of ground and low-altitude obscl-vations from the polar regions in probing the far magnetosphere. Such probing is possible due to the strong electromagnetic and plasma coupling which exists between the high-latitude ionosphere and the outer magnetosphere. The recent publication of T/K, M<~~nync~/osp/~~~, fhr High-la/iIU& lonmpherc. md Their fnfrruc.tion.s. the Proceedings 01‘ a Royal Society Discussion Meeting held in London in May 1988. provides a timely and welcome summary of several of the hey topics and pressing questions in the exciting and rapidly developing field of magnetosphere ionosphere coupling. The meeting and the book arc dedicated to the memory of SYI)~\FY C~MPMA~. a great pioneer in Earth space plasma physics. the centenary of whose birth occurred in 1988. Dcspltc initial impressions to the contrary (the magnctospherc on the front cover bearing a closer resemblance to Jupiter’s than to the Earth’s. and numerous typographical errors on the Contents page), the book has much to he recommended. It is attractively produced and generously illustrated with I7 colour plates and a variety of other high quality ligures. The Editors (Sir GKANVILL~ BEYNOK, Sir RoHt K I B~YI), STA\ COWIXY and MICHAEL RY(‘KOFT) have assembled an imprcssivc international panel which includes DAvlt) SOUTHWOOD. BENGT HLLTQVIST and TOM Moo~r. The hook contains I5 papers covering a range of topics from the violent mass, momentum and energy transfer processes associated with reconnection at the dayside magnetopause and in the magnetotail to the complex rcsponscs of the hiphlatitude ionosphere to these and to other magnetospheric forcing processes. There is a sensible balance between obscrvation, lhcory and computational work. The papers contain a strong rcvicw bias, but thcrc is also fresh material with the recent salellitc observations from ViAi+/ and AMP TE and the new ground-ha& results from EISCAT ranking as special hlphlights. The papers forming this volume were published first in the Pllilo.so~/~hic~rrl7i~m.~rr~tiot1.cof /he Royd Society of London. Scrics A, volume 238. pages 35 287, 1989. and, considering the hook’s cost (f50). this may prove a more accessihlc bource of reference. Most authors have minimised the use of mathcmatlcs but the material will appeal most to advanced postgraduates and research workers familiar wtth the vast ~rangc of technical terms and concepts which, regrettably. 15 making the field increasingly obscure to fresh students. Inclusion of the discussion following each paper forms an mtcrchtlng and worthwhile feature of the book. Highhghting individual papers is never easy especially when the overall standard is high. and different readers will douhtleqs have their oun favourites. However. to this

reviewer two papers stand out as providing the best conbinatlon of sensible revlcw material, important new results and readability : those by Hui.ryvlsrand by WII.I.I,%~MS. VIIU)I and COWLEY. The aurora1 oval is a key region in magnetosphereeionosphere coupling and the results from the Swedish satellite b’ikiqq are having a major impact on ourunderstanding of this complex region HLI TQ\IST prcscnts exciting ncu findings from Vi/~&q which focus on the dayside aurora, a region which now appears to bc gcncrally more active than the nightside aurora. NCM. aurora1 fcaturcs are observed. including large-scale curls (perhaps cIrI\cn unstable by celocity shear) and aurora1 ‘hot spots’. while the relevance of small-scale parallel electric ticlds in accelerating aurora1 electrons IS vividly confirmed. WII 11ms (21 trl address substorms. the violent magnetotail disruptions \\ hlch lead to brilliant polar auroras and the catapulting of ;I giant plasmoid into interplanetary space. They cmphasisc the mcrlt of combining space and ground-based obscrvallons (EISCAT radar data in particular) for a more complclc understanding. The popular ‘neutral-llnc‘ modei of rubstorms predicts two separate sources of plasmatlow and hoth these are observed in the nightside EISCAT da(a. TheI-e ih also cvidcncc for time-dependent structure suggesting the interesting possibility that time-dcpendcnt reconnection akin to Hux transfer events at the magnetopause may hc occurrinp in the maenetotail. A surpiising omission is the lack of covcragc sl\en to Birkeland (magnetic field-aligned) currents. surely a vital component In all magnetosphere ~ionospherc coupling mod&. An article highlighting the keq rcmainmg qucjtlonh and providing a thoughtful look ahead would LIISOhake been wclcomc. In this regard the value of the polar cusp ionosphere as a window for monitoring solar wind Magi netosphere coupling at the magnetopause needs cmphastslng and mcnlion should bc given to the exciting nev, cxperimcnrs and rcscarch Initiatives already underwahl or planned such as the PACE and Spitzbergen polar cap radars and the GEM (Geospacc Environment Modelling) project. The ,Zlt/,ync,ro.sl~i~c~c,/i/c, Hiqi~-i~~~i/ud~ /o/r~~.~/hvc~.md their In~~~rtrc~/iorr~ is an attractive and worthuhilc publication providing a timely. though not cxhaustibc. survey ofa subject which must surely grow in importance during rhc I99Os. I recommend the book as a useful rcfcrcncc to all Ircscarch croups interested in Earth space plasma physic\. Ro\al

M~KK SAL xI)I;Ks Society 19x3 Rcccarch Ecllou Imperial (‘ollcgc. London

Fractals in Geophysics, SCHOLZ C. 11. and M.AVXLUKO~ B. B. (cds). 1989, 320 pp.. Birkhiiuscr, Basci, sFr 7X. DM90. US$50.50 (pb). In December 1987. a symposium on ‘Fractals in Geophysics‘ was held at the American Geophysical Union meeting in San Francisco. This book, a special issue of Puw ~4 .Appiid Geophy.vic~.s. contains papers presented at that symposium. and one. by MANUELHKOT,submitted since An ohjcct 01 quantity that can be described as a fractal euhlhlt\ scale