During October 2000 through March 2001 the Cassini spacecraft was within 0.5 AU of Jupiter. Using a data set which combines the Cassini magnetometer data with that of the Galileo spacecraft in orbit around Jupiter we provide the first perspective on solar-planetary interactions at Jupiter using dual site measurements. We show the coherence over large scales of much solar wind field structure and show the response near Jupiter to upstream changes. In particular, we show the first evidence of northward IMF leading to Jovian magnetopause erosion due to magnetopause reconnection.

We consider the distributions of field-aligned current and auroral electron precipitation parameters in Jupiter's middle magnetosphere which have been computed from given models of the magnetospheric magnetic field, but where in each case the plasma angular velocity profile has for the first time been calculated self-consistently from the theories of Hill and Pontius. The magnetic models considered are a simple planetary dipole field, and a current sheet field based on fly-by observations. It is shown that while the solutions for the angular velocity profile show remarkably little dependence on the magnetic model, nevertheless the field-aligned currents are strongly dependent on the model, due to the differing mapping of the field lines between the magnetosphere and ionosphere. For typical jovian parameters it is shown that the field-aligned currents are more than an order of magnitude larger for the current sheet field than for the dipole, with major consequences for predicted auroral effects.

Ulysses has completed its second fast latitude scan of the inner heliosphere, started under conditions of solar maximum activity above the south pole in November 2000, but finding high speed solar wind streams over the north pole (from August 2001) from the newly formed coronal holes, carrying the new, reversed polarity magnetic fields. We analyse the intermittent nature of magnetic fluctuations as a function of heliolatitude and of the changing level of solar activity and we compare these results with the study of the magnetic fluctuations from the previous fast latitude scan in 1994-95, made under considerably more stable coronal conditions.

Particle in cell simulations of high Mach number quasi perpendicular shock waves reveal a nonthermal downstream electron energy distribution with a high energy tail. Ions reflected at the shock, forming the foot of the shock form a high-energy counter streaming ion beam causing fast-growing two stream instabilities. These instabilities lead to the formation of electron phase space holes which can trap electrons thus accelerating them by the surfatron mechanism. Here a wave structure travelling perpendicular to the magnetic field lines can trap electrons in the potential troughs which are in turn accelerated by the electric field seen in the zero phase velocity frame of reference of the wave. The electron phase space holes necessary for the acceleration in high Mach number shocks disappear however for low Mach numbers or high plasma beta. The parameters of the bow shock of Mercury lie in the range where these mechanisms might be important and electrons could be found to be accelerated to supra-thermal energies.

The MHD description of collisionless shock waves gives a very clear picture of their expected structure in terms of magnetic and plasma parameters. In particular the magnetic field magnitude discontinuity is predicted to be accompanied by a deflection in the magnetic field at precisely the same time. The Ulysses spacecraft has provided us with a large number of interplanetary shock wave observations which demonstrate a whole range of shock structures. A set of these events is used in the work presented here in order to compare the observed magnetic structure with that dictated by theory. Although the detailed observations of these shock waves were expected to be complicated by surrounding fluctuations, the extent of the deviation from the MHD description is surprising. The results open the long standing question as to what should be considered a collisionless shock wave especially at the weak end of the spectrum.

Ulysses is the only spacecraft to have sampled the solar wind at high heliographic latitudes. Around its perihelion, the spacecraft travels from 80 degrees south to 80 degrees north in only 10 months, thus providing a "snapshot" of the state of the Sun during that period. The first fast latitude scan in 1994-1995, during solar minimum, clearly showed a dipolar solar magnetic field, with the heliospheric current sheet confined to low latitudes. Ulysses has now completed its second fast latitude scan, during solar maximum. Ulysses reached maximum southern latitudes in late 2000, before solar polarity reversal had occurred. By the time it reached maximum northern latitudes in late 2001, it was sampling wind of the same magnetic polarity as had been seen near the south pole the previous year. Ulysses has therefore gathered unique data on the Sun's magnetic polarity at all latitudes as it was reversing. We present an overview of these data, contrasting the 2000-2001 observations with those at solar minimum.

Statistical properties of the interplanetary magnetic field (IMF) fluctuations can provide an important insight into the processes occurring in the solar wind across the different temporal and spatial scales. Recently, considerable effort has been dedicated to analysis of the Probability Distribution Functions (PDF) of the velocity and magnetic field fluctuations. These functions exhibit clear non-Gaussian properties on small time scales while the large scale dynamics appears to be uncorrelated. Here we obtain a universal scaling of the PDFs of the magnetic field fluctuations over their full measureable length. We find that rescaling with two parameters is sufficient to collapse distribution curves over a range of three orders of magnitude in the magnetic field fluctuations. An anomalous diffusion analysis, derived from the Fokker-Planck equation, is applied to verify the functional dependence of the diffusion coefficient on the magnitude of the magnetic field. The result strongly suggests the existence of a common, nonlinear process on the time scale up to about 25 hours.

The Tromso heater is used to excite field-aligned plasma density irregularities that are seen by the Co-operative UK Twin-Located Auroral Sounding System (CUTLASS). For one of the experiments conducted during the experimental campaign of October 1998, the heater beam was scanned spatially from 30 degrees north to 30 degrees south for periods ranging from 1 minute to 1 second. For the higher-scanning-frequency scans, the spatial position of the heater beam changed in less time than that required to generate irregularities and the resulting backscatter powers were lower than those for the slower spatial scans. Also, the backscatter powers obtained by CUTLASS were higher from ranges to the south of the vertical beam direction, indicating that artificially generated irregularities were excited more strongly close to the direction parallel to the geomagnetic field.

Novel use of existing optical technology and advances in detector technology have recently produced some examples of spatial and temporal behaviour of the upper thermosphere that are on the scales of tens of kilometres and minutes, respectively [Greet et al., 1999; Conde et al.; 1998, Aruliah and Griffin, 2001; Conde et al., 2001]. Such behaviour of the neutral atmosphere has not been expected. Current theoretical [e.g. Fuller-Rowell et al., 1996; Richmond et al., 1992] models use spatial scales of the order of hundreds of kilometres; and the predicted response time for the neutral atmosphere is given in terms of hours [e.g. Rishbeth and Garriott, 1969]. Considerable discrepancies between observations and model calculations of Joule heating and momentum transfer have been found, which can be explained by meso-scale behaviour where random variations in ion flow increase Joule heating, but also reduce the momentum transferred to the neutral atmosphere. However, the complexity of the dynamics of the upper atmosphere in the auroral and polar cap region demands higher resolution thermospheric measurements, which the Scanning Doppler Imager instrument would provide, to complement the increasing resolution of ionospheric measurements in these regions.

Results are presented from a multi-instrument investigation of the daytime ionosphere at high latitude, under conditions of Bz<0, that provide evidence for the tongue-of-ionisation (TOI) in winter over Svalbard, contrary to model predictions. The TOI, transporting photoionisation from sub-auroral latitudes into the polar cap, has been identified in three successive tomography images at latitudes on the equatorward edge of the auroral region in the post-noon sector. Simultaneous observations by the ESR incoherent scatter radar reveal cold plasma of increased density in the vicinity of the throat region where the TOI enters the polar cap. Supporting evidence for the feature is provided by optical emissions measured by meridian scanning photometers, together with plasma drift and particle observations from DMSP satellites.

For the first time, F-region ion temperatures have been measured by optical methods. The Lancaster Fabry-Perot interferometer, located at Skibotn, Norway (69.36^o N, 20.33^o E), has been used to observe upper-thermospheric neutral temperatures, using the O¹D emission at 630 nm, and F-region ion temperatures using the O⁺(²P) emission at 732 nm. Temperatures are computed from the Doppler broadening of the selected emissions. The nighttime O⁺ emission is stimulated by auroral particle precipitation, whereas the O¹D comes either from precipitation or the airglow. Both emissions come from F-layer altitudes (O¹D ~ 260±20 km and O⁺(²P) ~ 280±80 km). Dual wavelength measurements were made during February 2001 and clearly show that the ion temperature is equal to or greater than the neutral temperature, as expected. On 3 nights the EISCAT radar was operating. Although the observing volumes are separated by ~300 km, there is excellent agreement between the incoherent scatter and Doppler broadening methods of inferring ion temperature.

Typical auroral/airglow wavelengths useful for Fabry-Perot interferometer observations:

Emission	Wavelength (nm)	Height (km)	Quantity
OH(6,2)	843.0	87 ± 3	Un + Tn
OIS	557.7	~ 97 and ~ 115	Un + Tn
OID	630.0	~ 260 ± 20	Un + Tn
OIIP	732.0	~ 280 ± 80	Vi + Ti

Techniques have been developed to extend the Arecibo radar's capabilities to include the concentrations and temperatures of the light ions, H+ and He+, up to an altitude of around 2000 km. These improvements now mean that it is possible to compare results from the Arecibo radar with results from the DMSP satellites (approximate altitude of 800 km). Results from the Arecibo radar have shown significant layering of He+ (~20%) at approximately 700 km altitude. Corresponding data from the DMSP-F13 satellite also show an increase in the He+ fractional content above Arecibo. Initial results from the coupled thermosphere-ionosphere-plasmasphere (CTIP) model show that the model is replicating the He+ layer above Arecibo.

Observations from the EISCAT VHF incoherent scatter radar system, during a run of the common programme CP-4, reveal a series of poleward-propagating F-region electron density enhancements in the pre-noon sector on 23 November 1999. These plasma density features, which are observed under conditions of a strongly southward interplanetary magnetic field, exhibit a recurrence rate of under 10 minutes and appear to emanate from the vicinity of the open/closed field-line boundary from where they travel into the polar cap; this is suggestive of their being an ionospheric response to transient reconnection on the dayside magnetopause (flux transfer events). Simultaneous with the density structures detected by the VHF radar, poleward-moving radar auroral forms (PMRAFs) are observed by the Finland HF coherent scatter radar. It is thought that PMRAFs, which are commonly observed near noon by HF radars, are also related to flux transfer events, although the specific mechanism for the generation of the field-aligned irregularities within such features is not well understood. Interpreting the HF observations with reference to the plasma parameters diagnosed by the incoherent scatter radar suggests that the irregularities within the PMRAFs are generated by the presence of gradients in the electron density, these gradients having been formed several hundred kilometres equatorward through structuring of the ionosphere in the cusp region in response to transient reconnection.

On the 13th February Cluster observed two magnetic field reversals in the solar wind and a large scale rotation of the magnetic field in the magnetosheath. These structures were also observed by ACE upstream of the Earth at the L1 point. A comparison of Cluster and ACE data is presented. Cluster multi-spacecraft analysis and MVA is used to determine how these structures evolve between L1 and the Earth.

The Kelvin-Helmholtz instability (KHI) and the resonant flow instability (RFI) of magnetohydrodynamic (MHD) surface waves on the magnetopause are studied. We model the magnetopause interface by a thin nonuniform layer where resonance may occur, which separates two semi-infinite homogeneous regions with different finite values of plasma beta. Three different kinds of surface modes (labeled as "primary"- and "v"-modes on sides 1 and 2, respectively) may exist. The v-modes, which appear only in the presence of a velocity shear, remain almost unaffected by the flow in the corresponding rest frame. We found, v-modes can only be excited for a limited range of velocity shears. These v-modes do not interact with each other, but their interaction with primary modes leads to KHI confined to finite velocity intervals when the mode energies are of opposite signs. On contrary, primary modes do exist even in the absence of a velocity shear.

The negative energy primary modes can be resonantly unstable for flow velocities in the magnetosheath much smaller than those required for the KHI. However the growth rates of RFIs are correspondingly smaller than those typical for KHIs. Possible applications to observations in the terrestrial magnetosphere are discussed.

For several hours an extensive variety of instruments was monitoring the dayside magnetosphere and ionosphere. Flux transfer events were observed by Geotail on the dawn magnetopause as the spacecraft passed from the magnetotail into the magnetosheath. Excellent coverage of the entire dayside high-latitude ionosphere was achieved by all of the northern hemisphere SuperDARN radars. The SuperDARN radars in the dawn sector, in the vicinity of Geotail's magnetic footprint, measured temporally varying convection velocities. Low-altitude satellites were monitoring both the size of the auroral oval and particle precipitation in the cusp footprint. This extensive data set will be discussed.

Solar energetic particles (SEPs) are accelerated in the solar atmosphere during flare and coronal mass ejection (CME) events. The characteristics of SEP time intensity profiles at 1 AU have been studied for decades, and the current understanding is that they can be divided into two classes: impulsive events, associated with flares, and gradual events, associated with CMEs. We examine SEP data at 5 AU from the Sun, from the Ulysses Anisotropy Telescopes instrument, and discuss how the larger distance from the Sun affects the measured time intensity profiles. A comparison with measurements from the two Helios spacecraft at distances between 0.3 and 1 AU is also presented.

A force free flux rope model has been used to determine the gross properties of magnetic clouds (MCs) observed by Ulysses from mid 1996 to present day. As solar max occurred within the time period examined and thanks to Ulysses' unique orbit, MC properties from a wide range of heliographic latitudes have been determined. Presented here are the MC axis orientation results. We show that there are distinct preferred orientations, and that these preferences seem to be independent of heliographic latitude.

Analysis is made of approximately three years of solar wind data from NASA's ACE spacecraft. The relationship between the magnetic field intensity and speed of magnetic clouds found by Gonzalez et al., [1998] is seen to extend to all events in the solar wind possessing a high field strength. Solar wind events with higher magnetic field intensities have a stronger level of correlation between maximum magnetic field intensity and maximum speed; events with |B| >18nT for 3 hours showing a significantly stronger correlation. In the data-set considered 24 such events are present, half of which are magnetic cloud-like, the remaining half having no ordered field structure. Sixteen of the events are associated with halo CMEs leaving the Sun 2 to 4 days prior to the leading edge of the events arriving at ACE. A weaker correlation also exists between southward magnetic field and speed.

Previous work has shown that the dayside equatorward edge of coherent HF radar backscatter having large Doppler spectral width is coincident with the equatorward edge of the cusp particle precipitation. This enables the boundary between high and low spectral width backscatters in the dayside MLT sector to be used as a proxy for the location of open/closed field line boundary. The work presented here employs magnetic conjugate SuperDARN coherent HF radars to make an interhemispheric comparison of the location and variation of the spectral width boundaries. Agreement between the magnetic latitudes of the boundaries in both hemispheres is remarkable. Correlation coefficients between the latitudes of the boundaries are larger than 0.70 for all conjugate beam pairs employed in this study. The temporal variation of the magnetic latitude of the spectral width boundary follows the same equatorward trend in both hemispheres. This signature is consistent with the accumulation of open flux in the polar cap by magnetopause reconnection, expected when IMF Bz is negative. Boundaries in both hemispheres also exhibit short-lived poleward motions superposed on the general equatorward trend, which follows the the onset of substorm expansion phase and temporal northward excursion of IMF Bz during substorm recovery phase. In addition, there is an interhemispheric difference in response time to the substorm occurrence between two hemispheres such that spectral width boundary in the Southern Hemisphere starts to move poleward 10 minutes earlier than that in the Southern Hemisphere. We discuss this difference in terms of interhemispheric asymmetry of substorm breakup region in longitudinal direction associated with the effect of IMF By component.

HF radar backscatter which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsų has been demonstrated to provide ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by the CUTLASS HF radars. Data from the SP-UK-OUCH experiment have revealed small scale (high azimuthal wave number, m) waves predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAMMICE instrument indicate the presence of a non-maxwellian ion distribution function. Further statistical analysis has been undertaken using the Polar TIMAS instrument to reveal the prevalence and magnitude of the non-maxwellian energetic particle populations thought to be responsible for generating these wave types. Such morning sector waves appear to be dominated by drift-bounce processes. Energetic particle populations responsible for generating these wave types will be discussed.

Measurement of the differential phase of transionospheric signals enables the determination, to within an unknown constant, of the integrated total electron content (TEC). The inversion of this data to produce two-dimensional tomographic images of the electron density has been carried out using TRANSIT satellite measurements and has been shown to produce useful information concerning the localised morphology of the ionosphere. The increasing availability of TEC measurements from ground and space-based GPS receivers has introduced the need to extend conventional two-dimensional tomographic imaging methods. We present a method for the two, three and four-dimensional inversion of satellite and ground-based measurements from diverse instrumentation. Results from the USA and the European region demonstrate the possibility of imaging the ionosphere from the auroral regions to the equator. We demonstrate the technique by showing a series of images and a "movie" of the ionosphere during the storm of July 2000.

Fisher & Tippett (1928) identified limiting extremal probability distributions of the largest events taken from each of many realisations of a system. These exremal probability distributions are found to arise naturally, for example in laboratory fluid turbulence and in X-ray flux from accretion disks - that is, where transport is anomalous and there are long-range correlations. An important issue (with application to space weather) is assigning a likelihood to extreme events in plasma transport, including in the coupled Sun-Earth system. Here we consider a simpler system - games of football - where events (goals) may or may not be correlated and where we have data from many realisations (games). We find in the case of worldwide domestic matches over the last thirty years that the probability distributions of goal scores are closely fitted by extremal distributions, whereas the Poisson or negative binomial distribution is sufficient to describe English scores from the same period.