Imperial College

Space and Atmospheric Physics

 

DJSDavid John Southwood

Professor of Physics


Career and research history (all at Imperial College London, unless noted).

My interests include:                                                                               

·  Solar terrestrial and solar planetary physics

·  Planetary science

·  Collision-free magnetohydrodynamics (esp. waves)

·  Space magnetometry

·  Earth Observation

as well as ..... a general interest in doing science from space.

Publication List

PhD work 1966-1970 and post doctoral work in USA 1970-71.

Launch Pad, BaikonurMy thesis, unusually for the time, concerned both theory and data analysis of low frequency waves in the earth's space environment. [The data came from the magnetometer on Explorer 33, a spacecraft that failed to achieve lunar orbit.] I was first to show that waves creating ULF (1-1000 mHz) signals on the ground were generated by the solar wind flowing past the magnetosphere (Kelvin-Helmholtz instability). In the USA, I started looking at the large amount of data that was now accumulating in the magnetosphere proper and started my interest in non-linear large scale resonant effects between such waves and the Earth's radiation belts. This has direct links to plasma stability issues in laboratory or controlled fusion devices. My PhD supervisor, Jim Dungey, should take most of the credit for the inspiration at this time (to see more on this see my recollections: An Education in Space Physics, in Discovery of the Magnetosphere, History of Geophysics Volume 7, ed. S. Gillmor, p. 185, American Geophys. Un., Washington, 1997 - as indicated there, Jim was way ahead of everybody on many problems. For example, he was thinking about the principles behind the Cluster space mission 30 years before it came to pass. Working with that man gave one something of a headstart.) The picture on the right shows me (on August 9 2000) in front of the Soyuz rocket at the Cluster launch site in Kazakhstan; in the mid-sixties one could not have envisaged being ever on a launch pad at Baikonur, let alone there for the Cluster mission launch.

Lecturer, 1971-1981,

During the ten years 71-81 I developed a lot of the early understanding (using theory and data from US satellites and ground data from Canada and UK) of the way magneto-hydrodynamic waves couple the solar and terrrestrial environment. My best known work is the field line resonance theory published in 1974, which now underpins nearly all thinking in the subject. The genesis of the idea came from a visit to Jack Jacobs’ department in Alberta in 1970. The plot shown below right was shown to me by John Samson, then a student of Gordon Rostoker's. I then took well over a year to write it up my ideas (Things were more relaxed then.) and then several years to get them through review - the longest for any of my papers. The second most famous work is probably the joint work with Jeff Hughes, then a student, on the manner in which low frequency signals propagate from above the ionosphere to the ground. This work is now seminal and part of it carries Hughes' name 'the Hughes rotation'. Personally, I am just as proud of my early work using spacecraft data to test simple MHD ideas (waves driven by wind, etc.) which got a lot of attention at the time and my work on the stability of particles in the radiation belts, which was not really appreciated until the 90's. In collaboration with Bill Stuart of British Geological Survey, I worked on the development and use of data from chains of magnetometers in UK and Scandinavia to test ideas developed in my theories. Working with Bill on ground-based magnetometers (as well teaching and working with Peter Hedgecock of Imperial) got me interested in experimental problems.

Samson/Rostoker/Jacobs plotDuring this period, I started collaboration in interpretation of charged particle instrument data with the American scientist, Margaret Kivelson. Our skills are complementary and, thirty years on, we still regularly work together.  Our collaborations have expanded to encompass many more areas; and some of my nicest work [e.g. the prediction of global MHD waves, non-linear ionospheric vortices, non-linear theory of the mirror instability, slow (MHD) mode standing bow wave, frequency doubling in ULF signals] has been done with her.

Reader in Physics (and Head of Space Physics, from 1984), 1981-86,

During the next half decade I did a large amount of work on the time and spatial structure of coupling between the solar wind and the sun and ventured into true experimental work, with the help of C. T. Russell and my then colleague, Stan Cowley, delivering the magnetometer for the British ' UKS' spacecraft launched in 1984, as well as helping to develop a very large UK effort in the study of the geomagnetic effects on the ground. Along with Stan's work, my contributions to the understanding of 'flux transfer events' were influential and I made the first attempts to relate the bursts of FTE related flow seen by radars in the polar regions to what spacecraft were seeing at high latitudes (now this is a very international activity, tied into 'space weather' in which the UK has a very high reputation).

In parallel, I joined the Galileo spacecraft magnetometer team led by Margaret Kivelson at UCLA (around this time, after a year spent teaching at UCLA 1978-79, I started a long term visiting position at UCLA) and started work on Jupiter and Saturn. In particular, I began working on the electromagnetic environment of the jovian moon Io.

Professor of Physics (and Head of Space and Atmospheric Physics), 1986-94

My most important work on solar-terrestrial physics from this time is that on the 'turbulence' and shock like formations seen in the ' magnetosheath' region separating the solar wind proper from the Earth's magnetosphere. This has opened up as a large topic of research subsequently, partly in anticipation of 'Cluster'. During this period, with my colleague, Andre Balogh, we saw the Ulysses solar polar orbiter spacecraft launched, where Andre had become PI of the magnetometer and we started work on the Cassini Saturn Orbiter magnetometer, which I was to lead.

The flyby of Jupiter by the 'Ulysses' spacecraft led to a lot of work involving me and my postdocs and students in linking in situ measurements of the jovian magnetosphere to images of the aurora recorded by the Hubble space telescope at Earth. We also discovered pieces of the magnetosphere detaching and blowing away ('magnetic nulls') and then went back and discovered that they had been detected but not interpreted in earlier flybys of Jupiter.

At this time I also started increasing my interests in environmental research as my research group had merged with the Atmospheric Physics group. Eventually, we established a new EO group within the Space and Atmospheric Physics group at Imperial. In order to feel comfortable in charge of such an activity, I also taught myself enough meteorology and allied science to start teaching an undergraduate course in atmospheric physics. I remain convinced that physicists are greatly needed not only in meteorology, but in all environmental sciences.

Head of Blackett Laboratory, 1994-7

In this time, despite the very satisfying job of heading an extremely good and broad-based Physics Department, I managed to keep up my personal research.

The Galileo data harvest started to come in in the mid-nineties. I was involved in the discovery of magnetisation in the asteroid 'Gaspra' and then in the extraordinary series of discoveries of the magnetism of the Galilean moons of Jupiter. I was a strong proponent within the GLL team of the presence of an internal magnetic field of Io. This was controversial but I felt vindicated by the subsequent finding of the undeniable presence of an internal field at Ganymede. I hope that data from the recent Io passage (in May 2000) clinches the issue for everybody but these results are not yet public. I also did some of the first analysis of Callisto, which excites a magnetic signature without having internal magnetism. Because of the implications for internal heat sources, these discoveries overturn many of the simple ideas of planetary formation and solar system history. [By going to ESA in 1997, I missed out on joining in the work on Europa and the detection through magnetic induction of the internal ocean.]

CassiniMy guess is that the Galileo science will be matched in time by what Cassini will find at Saturn. We won the competition to build the magnetometer for the NASA Cassini spacecraft in 1989. The instrument was launched in 1997. With contributions from TU Braunschweig (Germany) and the Space Sciences group at JPL (USA), it is the first magnetometer with 'absolute' measuring capability to be used on a planetary mission. The performance of the instrument in Earth flyby last year was exemplary (see below). Frankly, the Cassini magnetometer is going to provide a cornucopia of science once it gets to Saturn. I expect to work on the data well into my retirement.

ESA (EO Strategy) 1997-2000

Given an opportunity to go into the European Space Agency when it was clear a new path needed to be set for Earth Observation science, I took leave from Imperial and became Head of Earth Observation Strategy. I worked first with R. M. Bonnet and then with Claudio Mastracci to set up and get funded the 'Living Planet' programme. This meant that I had to cut back on personal research more or less completely, apart from work done as a visiting professor at UCLA and managing the Cassini magnetometer. Mike Reynolds and Chris Readings (both of ESA ESTEC) were very close colleagues in the effort to get the programme going. It was an awful lot of fun. For me, using space to monitor the Earth globally and manage it better will come about in the future. The only question is how quickly we get there. By the time that I left ESA, four new 'Earth Explorer' space missions were committed [Cryosat, GOCE (Global Ocean Circulation Explorer), The EarthSMOS (Soil Moisture and Ocean Salinity) and Atmospheric Dynamics]. The 'shrunken apple' picture on the left illustrates the Earth's gravity field, the GOCE spacecraft's territory. As well as contributing to our knowledge of the solid Earth, the gravity field of Earth is fundamental to understanding ocean circulation (thus important aspects of climate change) as well as many practical civil and military uses.

The new style of funding the new programme introduced, 'Envelope' funding, gave the agency a long-term plan for Earth science. This gave a new potential for discussing international cooperation and a solid basis was set up for future joint work with Japan and USA.

Regent's Professor, University of California, 2000

I completed my three years leave from Imperial by leaving ESA after 2˝ years and taking up a Regent's Professorship at UCLA. This position allowed me to get back into research and teaching. As well as getting a book (on Hydromagnetic Waves in the solar terrestrial system) well and truly started, it allowed me to look at ideas of teaching and publishing using the Web. I am thinking about releasing the book material directly through the Web, prior to any other form of publication, in order to get feedback before giving any thought to hardcopy form. You can look at some sample chapters on this site. In the USA, I got a lot of new research started – most important is a series of predictions (with Margaret Kivelson) of what will be seen during the Cassini Jupiter flyby later this year.

ISSI, 2000 (and prospects for Saturn system science)

Cassini Earth SwingbyThe exile from Imperial ended with two brief sojourns at the International Space Science Institute in Berne, Switzerland, whose Science Committee I have chaired since ISSI’s founding in 1995. Here, at the Piccadilly Circus of solar system space physics, it was good to interact with some of the variety of scientists who pass through. I found the time to analyse in depth the data taken by the Cassini magnetometer as it flew by Earth. The instrument performed marvellously; it is going to do tremendously well in its tasks at Saturn. In fact, remarkably, it looks as if we have made at least one new discovery (material peeling off the plasmapause) - using the high time resolution and sensitivity of the instrument. We also got some new light on several other phenomena; 'lower hybrid noise' in magnetic nulls in the sheath, a 'whistler' mode wave apparently trapped inside the magnetopause, signatures of heating in the magnetopause, and the potential signature of a surface wave on the plasmapause. Plots of magnetometer data are famously dull and typically show simple time series. The plot on the left shows an alternative way of using data from a high resolution low noise instrument. It is a spectrogram derived from one of the fluxgate sensors. It shows ion cyclotron wave noise just inside the terrestrial magnetopause, very near the subsolar point on August 18 1999. The superpose lines are fractions of the local ion cyclotron frequency, fg (proportional to the background magnetic field strength). There is broad band noise in a boundary layer (0-120 s) and then, once inside the magnetosphere proper, a stop band appears. This band is speculated to be due to the presence of Oxygen ions (of terrestrial origin) in the magnetosphere itself. This kind of analysis means the instrument has a lot of potential for studies beyond just magnetism in the vicinity of Saturn, its rings and moons.

'Committee Man'

Through my scientific and academic career, I have also done a lot of committee work. Committees are now a necessary activity in facilitating science but membership of them is not always something to be proud of.

I have been on committees in Britain (SERC/PPARC, NERC, Royal Society and others) and the USA (NASA and AGU), but also for the European Commission, Norwegian Research Council, Finnish Academy, and various universities/institutes from the University of Tokyo to the International Space Science Institute in Switzerland.

Despite an avowed scepticism of committee-dom, I have chaired a lot. In the British SERC (- predecessor of PPARC), in the eighties, I enjoyed chairing the Astronomy Theory Panel and the Solar System Committee. My earliest chairmanship in ESA was of a committee to bring the SOHO/Cluster Cornerstone within budget (in 1988). Descoping is not really something to boast about. Later in ESA though, I am extremely proud of having been both chairman of the ESA Space Science Advisory Committee (1990-1993) and then the Science Programme Committee (1993-1996)(during the development of the Horizons 2000 long term plan). In the AGU, I have chaired the Fleming medal committee and the Fellows Committee. Giving credit for good work is worthy of pride and I am pleased that during my chairmanship of the latter, the Revelle medal for work in oceans, atmospheric science and climate change was proposed and the Committee got it through. In the RAS, I was Vice-President (1989-91). Here, with Roy Jady, we did better by not only proposing the institution of the 'Price' medal, now awarded for Geomagnetism and Aeronomy, but also finding the funds. I have also chaired several committees/panels in the International Council of Scientific Union organisations, COSPAR and IAGA.

Future

On October 19th 2000, the ESA Council chose me to become the Director of Science of ESA.  I was ‘over the moon’.  It will be hard to deliver the ambitious programme that Horizons 2000 now is.  Even harder will be succeeding Roger Bonnet, who created the present programme.  However, it is wonderful to have been given the opportunity. 


Last modified 20th October 2000