Abstracts

Understanding the behaviour of relativistic electrons in the Earth's inner magnetosphere during storms and substorms is a current challenge in magnetospheric physics.In particular, predicting the appearance of highly energetic "killer" electrons in the outer radiation belt is an important facet of space weather forecasting.Relativistic electrons, generated during the recovery phase of a typical geomagnetic storm,constitute a serious potential hazard to instruments carried by orbiting spacecraft.In this paper,we present a model in which the energization of electrons takes place by means of stochastic gyroresonant interaction between lower-energy (several hundred keV) seed electrons and whistler-mode chorus waves.A model kinetic equation for the electron energy distribution is developed,involving a resonant diffusion coefficient incorporating whistler-mode wave spectral data for a typical storm.The model solutions are found to match well with the observed profiles for the electron flux.It is concluded that the mechanism of stochastic acceleration by whistler-mode turbulence is a strong candidate for generating killer electrons during storms with a several-day recovery phase containing prolonged substorm activity. Furthermore,by examining several types of relativistic electron event,we show that enhanced chorus-mode waves generated during prolonged substorm activity can generate relativistic electron flux increases in the outer radiation zone,whether in the presence or absence of a magnetic storm.

We present observations of spatiotemporal variations in the dayside reconnection rate measured in the ionosphere during an extended interval of northward IMF. The convection electric field during this interval is measured in the high-latitude ionosphere using the northern hemisphere SuperDARN HF radar network. This is combined with an estimation of the location of the ionospheric footprint of the reconnection X-line, as determined by DMSP spacecraft overpasses and SuperDARN measurements, to determine the spatial variations in the reconnection electric field. We also present the temporal variation in the integrated reconnection voltage for an extended time interval which illustrates the transient nature of the reconnection process under these conditions.

Vlasov simulations of the current-driven ion-acoustic resistivity produced in Maxwellian and non-Maxwellian plasmas with similar moments are presented and compared, along with a concise stability analysis of ion-acoustic waves in Maxwellian and non-Maxwellian plasmas. Anomalous resistivity is excited for lower absolute electron drift velocity and reaches higher levels in non-Maxwellian plasmas when equal temperature species are considered. The magnitude of resistivity which can be generated by unstable ion-acoustic waves is significant for studies into magnetic reconnection at the magnetopause.

Recent results from long-term studies using radars have revealed a strong solar cycle signature in the extra-tropical atmospheric gravity wave activity in the Mesosphere-Lower-Thermosphere (MLT) region. A new zonally averaged mechanistic model of the middle atmosphere: the Stratosphere to Thermosphere Energy Variability Experiment (STEVE) has been developed to study the external forces on the MLT region which may account for the observed changes. The details of these model results will be discussed.

Whilst it is generally agreed that ULF waves with a high azimuthal wavenumber (m) have their energy source in wave-particle interactions, many questions still remain as to their exact generation mechanism. For example it is still not clear why a subset of these high m waves known as Giant Pulsations (Pgs) seem to be rare, morning based phenomena. These waves are thought to be generated through wave-particle interactions between standing wave modes and unstable particle distributions in the magnetospheric plasma population. This source of energy is here quantified by examining satellite data in the form of Ion Distribution Functions, (IDFs) and directly comparing these with the resulting wave energy dissipated into the ionosphere, using ground based radar data. We find that the estimates of the wave energy at the source and the sink are in good agreement. Finally, we present a statistical study of the distribution of the free energy of such particle populations as a function of MLT, using data from the TIMAS and CAMMICE instruments onboard the Polar satellite. The implications for the occurrence of both Pg and other high m waves will be discussed.

We perform a survey of the plasma wave and particle data from the CRRES satellite during 26 geomagnetically-disturbed periods to investigate the viability of a local stochastic electron acceleration mechanism to relativistic energies driven by Doppler-shifted cyclotron resonant interactions with whistler mode chorus. Relativistic electron flux enhancements associated with moderate or strong storms may be seen over the whole outer zone (3 < L < 7), typically peaking in the range 4 < L < 5, whereas those associated with weak storms and intervals of prolonged substorm activity lacking a magnetic storm signature (PSALMSS) are typically observed further out in the regions 4 < L < 7 and 4.5 < L < 7 respectively. The most significant relativistic electron flux enhancements are seen outside of the plasmapause and are asociated with periods of prolonged substorm activity with AE greater than 100 nT for a total integrated time greater than 2 days. These events are also associated with enhanced fluxes of seed electrons and enhanced lower-band chorus wave power with integrated lower-band chorus wave intensities of greater than 500 pT^2day. No significant flux enhancements are seen unless the level of substorm activity is sufficiently high. These results are consistent with a local, stochastic, chorus-driven electron acceleration mechanism involving the energization of a seed population of electrons with energies of a few hundred keV to relativistic energies operating on a time-scale of the order of days.

PMSE is a well documented phenomenon in which layers of electron depletion ('biteouts') are observed mainly in the polar summer mesosphere at heights of 80-85 km. Fractional electron depletions of up to 90% are observed in layers a few kms thick, and are due to immobilisation of electrons by aerosols associated with noctilucent clouds. Such layers are detected by direct measurement of electron density by rockets or by analysis of echoes from high power terrestrial VHF beams. This work is a numerical study of the perturbing effect of PMSE on subionospheric VLF propagation. We employ the NOSC VLF propagation code MODEFNDR for this purpose. We consider propagation at 20,40,60 and 80kHz on a transpolar path to Tromso with and without a homogeneous PMSE layer. We calculate the amplitude and phase shifts ('Trimpis') as a function of range from the transmitter from 500-6000kms. Various zero order electron density profiles Ne(z) are selected through the usual b and h' parameters. Depletion layers are modelled as truncated Gaussian depletion functions with height 85 km, thickness 4 kms and magnitude of 90%. All modes returned by MODEFNDR, both TM and TE are used in the modesum calculations. Perturbations in modal parameters due to PMSE, namely excitation factor, horizontal wavenumber So and attenuation factor are carefully analysed. It was found that if daytime electron density profiles are chosen that have relatively high values at 80km, such as b=0.35, h'=77km , then the resultant PMSE 'Trimpis' are quite small ~ -0.1à-0.2dB, ~1-2 degrees of phase, probably not observable. However profiles more associated with night or dusk, such as b=0.5, h'=80km give rise to sizeable perturbations ~20 degrees of phase and -1.0 dB, +5 degrees phase at a range of 6000km. There is considerable variability with range, particularly for values < 2000km and also with frequency. These computations could inform future experiments in which variations in transpolar subionospheric VLF propagation could be measured with a view to detecting changes due to noctilucent clouds. Special equipment: OHP projector

This work is concerned with the numerical modelling of the Trimpi effect and comparison with data obtained from the Antarctic peninsula. VLF transmissions from four US Navy transmitters, NAA, NPM, NSS and NLK have been received at four sites on or near the Antarctic sites, with many simultaneous Trimpis observed. The simulation code uses a 3D Born scattering model, in which the LIE is treated as an assembly of point scatterers. Propagation is based on modal theory and handled with NOSC VLF propagation software MODFNDR. The theoretical formalism permits cross modal scattering at the LIE which is generally found to be significant.

The computations assume large E/W elliptically shaped patches oriented E/W with maximum electron density perturbations of 1.5 el/cc and with a Gaussian vertical profile centred at a height of 84km. Patch dimensions are 300x1000kms, considerably larger than used in earlier work. Locating such a patch to the NW of the Antarctic peninsular gave consistent results for Trimpis in good agreement with those observed on the 10 transmitter-receiver paths utilised in the Antarctic experiments. Simultaneous events must be due to LIE's located near the receivers, which also rules out VLF Sprites as lightning is very rare in the Antarctic peninsula. Both observational and theoretical results confirm that in the case of 'classic' WEP Trimpis the LIE's are large weak structures rather than compact scatterers.

We are currently extending out numerical model to examine for the first time the time signature of the phase and amplitude Trimpis. The path from NPM (Hawaii) to Faraday in the Antarctic is being examined using the very large patch sizes determined earlier Using a variety of electron density perturbation profiles and a suitable model for electron perturbation decay, computed time signatures are being obtained in very good agreement with those experimentally observed. Results and initial conclusions will be presented.

We discuss the nature of the large-scale flow in Saturn's magnetosphere, and the consequent implications for the plasma flow in the ionosphere, and the coupling current system. The model predicts a four-ring system of field-aligned currents, it being proposed that the 'main auroral oval' is associated with the ring of upward field-aligned current that borders the polar cap (open-closed field line boundary).

We present evidence for the observation of high aspect angle HF radar backscatter from the auroral electrojets. Such backscatter is observed at very near ranges where ionospheric refraction is not sufficient to bring the sounding radio waves to orthogonality with the magnetic field; the frequency dependence of this propagation effect is investigated with the Stereo upgrade of the CUTLASS Iceland radar. We term the occurrence of such echoes the high aspect angle irregularity region or HAIR. These echoes are distinguished from normal electrojet backscatter by having low Doppler shifts with an azimuthal dependence that appears more consistent with the direction of the convection electric field E than with the expected electron ExB drift direction.

A mathematical technique, based on spectral representation of Green's function, has been developed to study the response of geomagnetic field line to any external arbitrary force. As an illustrative example, the technique developed was applied to see the field-line response of geomagnetic field line to the solar-wind pressure variation at the magnetopause boundary in the idealistic ionospheric conditions.

Coherent bacscatter radar observations with aspect angles up to and even exceeding 10 degrees off orthogonality have been reported over the last two decades. However, due to the lack of any convincing theory the validity of these observations has been in doubt. Results of a recent theoretical study are presented which do predict the destabilisation of plasma irregularities at large aspect angles. The feedback process which destabilises these irregularities is associated with the heating effect of parallel electron currents in the collisional lower ionosphere. The predicted thresholds and backscatter characteristics are presented and the effects of anomalous collisions is also discussed.

The EISCAT high power heating facility at Tromsø, northern Norway, has been utilised to generate artificial radar backscatter in the fields of view of the CUTLASS HF radars. It has been demonstrated that this technique offers a means of making very accurate and high resolution observations of naturally occurring ULF waves. During such experiments the usually narrow radar spectral widths associated with artificial irregularities increase at times when small scale-sized (high m-number) ULF waves are observed. Possible mechanisms by which these particle-driven high-m waves may modify the observed spectral widths have been investigated. The results are found to be consistent with Pc1 (ion-cyclotron) wave activity causing aliasing of the radar spectra, in agreement with previous modelling work. The observations also support recent suggestions that Pc1 waves may be modulated by the action of longer period ULF standing waves, which are simultaneously detected, on the magnetospheric field lines. Drifting ring current protons with energies of approximately 10 keV are indicated as a common plasma source population for both wave types.

The dynamics of Jupiter’s rapidly rotating magnetosphere is dominated by the outflow of material originating from the moon Io, orbiting deep within the magnetospheric cavity. The outward radial transport of this plasma results in the breakdown of corotation at all local times, which in turn sets up a large-scale magnetosphere-ionosphere coupling current system. We have recently discovered that the main auroral emissions at Jupiter are created by upward field-aligned currents associated with this large-scale transfer of angular momentum, and we have developed theoretical models which derive the properties of the auroral primaries. We will review this work for Jupiter and extend the theory to the kronian magnetosphere and examine whether or not the field-aligned currents associated with corotation enforcement are capable of producing the main auroral oval at Saturn, or if we expect the system to behave more like the Earth.

The Mars Global Surveyor obtained 43 electron density profiles of the Martian ionosphere during 9-27 March 1999. We compare these with ionosonde data on the E and F1 layers at several terrestrial sites. We find that the electron densities at the two planets are reasonably consistent, and show similar day-to-day variations in response to the day-to-day changes of solar activity.

On 07 September 2001 the Cluster spacecraft observed a ‘bursty bulk flow’ event in the near-Earth central plasma sheet. This paper presents a detailed study of the coincident ground-based observations and attempts to place them within a simple physical framework. The event in question occurs at ~2230 UT, some 10 minutes after a southward turning of the IMF. IMAGE and SAMNET magnetometer measurements of the ground magnetic field reveal perturbations of a few tens of nT and small amplitude Pi2 pulsations. CUTLASS radar observations of ionospheric plasma convection show enhanced flows out of the polar cap near midnight, accompanied by an elevated transpolar voltage. Optical data from the IMAGE satellite also show there to be a transient, localised ~1 kR brightening in the UV aurora. These observations are consistent with the earthward transport of plasma in the tail, but also indicate the absence of a typical ‘large-scale’ substorm current wedge. An analysis of the field aligned current system implied by the radar measurements does suggest the existence of a small-scale current ‘wedgelet’, but one which lacks the global scale and high conductivities observed during substorm expansions.

The terrestrial foreshock exhibits a wide variety of wave activity, resulting from the interaction of the solar wind with particles backstreaming from the shock. Most striking are the Ultra Low Frequency (ULF) waves observed with periods ~30s in the spacecraft frame; in this paper we present observations of such waves based on data from the multi-spacecraft Cluster mission. Following recent work identifying the intrinsic nature of the observed waves, more detailed observations of the propagation characteristics are presented, in particular we consider the propagation direction relative to the field. Details of the associated plasma properties are also discussed in the context of the generation mechanisms.

SPEAR (Space Plasma Exploration by Active Radar) is a new radar system currently being built by the Radio and Space Plasma Physics (RSPP) group at the University of Leicester. The capabilities of the system will be described as well as the progress on constructing this new facility at Longyearbyen, Svalbard.

A number of studies have shown evidence for power law-like power spectra in ground magnetometer data, indicating scale free behaviour. We present the results of a statistical time series analysis of one year’s worth of data taken from 4 Antarctic magnetometers. The location of these magnetometers is such that it allows us to investigate the multi-scale temporal character (from 10sec to 1 year) of the magnetic field variations through different geophysical regions i.e. sub auroral, cusp, LLBL and the polar cap. The way in which the multi-scale character varies between different geophysical locations may give us some insight into the origin of the multi-scale nature of the field fluctuations. For example, it may be possible to distinguish between models where the scale free fluctuations arise as a result of physics inherent in the plasma environments or those in which the fluctuations directly reflect the input of the solar wind such as a multi-scale generalisation of the Dungey reconnection model of magnetospheric convection.

On the 14th of December 1999, a large-scale ULF wave event was observed by the Hankasalmi radar of the SuperDARN chain. Simultaneously, the FAST satellite passed through the Hankasalmi field of view, measuring the electric and magnetic field oscillations of the wave at around 2000 km altitude, along with the precipitating ion and electron populations associated with these fields. Here the spatial and temporal characteristics of the wave are inferred from the SuperDARN radar and IMAGE magnetometer data. The expected signatures on FAST as it passes through the wave field are then compared with the observed field and particle data.

The link between Standing Shear Alfven waves in the earth's dipolar magnetic field and auroral arc formation has been well documented. The intense convergence of the field lines close to the auroral ionospheres leads to very large parallel current densities that require high energy electron beams to carry the current. The structure and formation of these downwelling and upwelling beams is not well understood and is not within the ability of MHD theory to fully describe. In this presentation, we will highlight work being done on a one dimensional cartesian field aligned model of standing Shear Alfven waves incorporating kinetic electrons. This will incorporate examination of constant field aligned density cases as well as increasing densities toward the polar ionospheres in an initial attempt to incorporate proper ionospheres. The framework extending the model to dipolar coordinates will also be highlighted.

Magnetic field data from Cluster FGM instrument are presented for cusp crossings on 17th of March 2001. During that day Cluster travels from the tailside magnetosphere through the dayside magnetosphere into the magnetosheath and past the bowshock. High altitude cusp crossing from 5 to 7 UT can be identified by a region of significant turbulence illustrating that cusp is a very dynamic region regardless of quiet solar wind conditions.

Results from a simple 1D model of the IAR are discussed, which represent the possible launch of Alfvén waves during modulated heating of the D-region ionosphere. The model parameters are defined by the actual ionospheric conditions, as defined by the EISCAT UHF radar, the Tromso Dynasonde and the high-resolution magnetometer at Kilpisjarvi. The modelling results are compared to electric field data from the FAST satellite, which successfully detected Alfvén waves as it crossed magnetic flux tubes conjugate to the Tromso heater during one such heating experiment on 8th October 1998.

The storage and subsequent removal of magnetic flux in the magnetotail during a geomagnetic substorm has a dramatic effect on the vertical extent of the cross-tail plasma sheet. The mid-tail plasma sheet is thought to thin during the growth phase and then rapidly expand after onset of magnetic reconnection at the near-Earth neutral line. Cluster’s Plasma Electron And Current Experiment (PEACE) allows 4-point observations of the plasma sheet lobe boundary as this interface passes over the Cluster tetrahedron. The relative timings of the boundary passage at each spacecraft allow a determination of its speed and direction of motion. Data from the 2001 and 2002 tail passes has been analysed. Average plasma sheet lobe boundary normal vectors and normal component velocities and their implication for the substorm triggering mechanism are presented.

We present and discuss Cluster PEACE observations of a possible near-earth X-line encounter during the period 13:30-14:15 UT, 21 July 2002. These observations were made at the beginning of the very active time interval (AE=1000 nT) which continued until 22 UT. At this time the Cluster spacecraft (X=-14,3 Re, Y=-11,2 Re, Z=-3,5 Re GSE) were near apogee and moving mainly in the +Y- and -Z-directions. Separation distances between spacecraft were around 0.6 Re. From 13:37 UT C4 was at the neutral sheet for 10 minutes while C1 and C3 were in the south plasma sheet. All spacecraft detected moderate tailward ion flows, from -400 km/s on C1 and C3 to -100 km/s on C4 (CODIF CIS data). At 13:48 UT C4 observed the flow to change direction. Two strong earthward plasma bursts (Vx~1000 km/s) were detected only by this spacecraft. Six minutes later, at 13:54 UT, C1 and C3 also encountered the neutral sheet and detected flow reversal signatures. Between this time and 14:15 UT the three spacecraft measured the same short-duration earthward plasma bursts (Vx~700 km/s). We interpreted these observations as signatures of pulsed reconnection and X-line motion past the spacecraft in a tailward direction. Between 13:48-14:15 UT WHISPER data show high-frequency electric field turbulence. PEACE data show bi-directional electron beams which coincide in time with the earthward proton bursts. In this presentation we will concentrate on the detailed study of the electron behaviour throughout the event using data from PEACE instrument onboard four Cluster spacecraft.

Forecasting the arrival of an ICME at the Earth is the first step towards advanced prediction of geomagnetic storm onset. Three existing models of ICME transit are compared to coronagraph and in-situ observations: all three models are found to perform with a similar level of accuracy (i.e. an average error between observed and predicted 1 AU transit times of approximately 11 hours). To improve long term space weather prediction, factors influencing CME transit are investigated. Both the removal of the plane of sky projection (as suffered by coronagraph derived speeds of Earth directed CMEs) and the use of observed values of solar wind speed, fail to significantly improve transit time prediction. However, a correlation is found to exist between the late/early arrival of an ICME and the width of the preceding sheath region suggesting that the error is a geometrical effect that can only be removed by a more accurate determination of a CME trajectory and expansion.

In this poster we use a combination of white-light data from the LASCO C2 and C3 instruments on SoHO and radio scintillation measurements from the EISCAT and MERLIN facilities to study interplanetary Coronal Mass Ejections (iCMEs). We discuss the classical definitions of CMEs and magnetic clouds and their counterparts in interplanetary scintillation (IPS) data and show that these may be used to distinguish cases when an iCME was passing across the ray-paths of the IPS observation. CMEs observed by LASCO are mapped out ballistically and IPS data over the succeeding hours and days searched for CME signatures. The IPS data for the observations are then fitted, with the CME geometry and location inferred from LASCO and EIT observations of the event. Results of several case studies are presented and the effects of different CME geometries discussed.

The solar minimum solar wind is clearly bimodal, dominated overwhelmingly by low-density fast flow from large polar coronal holes and high-density slow flow from above the equatorial streamer belt. At solar maximum the situation is more complex, with the heliosphere dominated by slow wind with narrow streams of faster flow occurring at any latitude - when observed at 1 AU these faster streams are generally slower than the polar fast streams observed by Ulysses.

Observations of Interplanetary Scintillation (IPS), in which the drifting diffraction pattern cast across the Earth by radio signals from an astronomical radio source scattered by density irregularities moving outwards is used as a flow tracer for the solar wind, can be used to study the evolution of solar wind structure in interplanetary space. In this poster we present results from an ongoing study of interaction regions between streams of fast and slow solar wind using IPS data from the EISCAT facility in northern Scandinavia. We also discuss observations of flow from the boundary regions of coronal holes and suggest that the slower "fast" stream velocities seen in-situ at solar maximum may result from the combination of two different physical processes - fast wind from boundary regions being intrinsically slower and the flow from narrow holes being disproportionately effected by interaction on stream boundaries.

Launched during summer 2000, the ESA Cluster mission allows for the first time the truly three-dimensional study of the spatial and temporal characteristics of the Earth’s geospace environment. The mission consists of four identical spacecraft orbiting the Earth in a tetrahedral formation in approximately polar, highly elliptical orbits. In the two years since the commencement of the mission’s science phase on 1st February 2001 the SuperDARN coherent-scatter radar network has been operating in a high-time resolution common mode (1 min full-scan) during 229 separate intervals when the conjunctions between the footprints of the Cluster spacecraft and the radars were particularly favourable. Clearly, by synthesising the detailed in-situ measurements of the configuration and motion of magnetospheric structures and boundaries provided by Cluster with measurements of ionospheric/magnetospheric convection from the SuperDARN network, it is possible to monitor magnetospheric processes over a wide range of spatial scales. Consequently, this dataset, totaling some 4500 hours of radar observations and including conjunctions at a range of latitudes at all local times in both hemispheres, is of primary importance when addressing many of the key outstanding questions in magnetospheric physics. A review of the radar coverage during the first 2 years of the Cluster missions will be presented.

A statistical study of high-latitude plasma flows during the magnetospheric substorm, using the SuperDARN radars. The study involved 67 substorms, identified with the IMAGE FUV instrument. The growth phase was characterised by an increase in high-velocity plasma flow into the polar cap on the dayside. Nightside backscatter moved to lower latitudes as the growth phase progressed. At the onset of the substorm expansion phase a suppressed flow region developed at the nightside, with fast plasma flows being diverted around it. There was also a sharp decrease in the occurrence of nightside backscatter. During both the growth and expansion phases there was a dawn-dusk asymmetry in the strength of the return flow.

By using Cassini as an upstream solar wind monitor we are able to infer increases in the interplanetary dynamic pressure upstream of Jupiter as the spacecraft approached the planet. Observations are made of the effect that these pressure increases have upon both the fields and particles within the Jovian magnetosphere as measured by the Galileo orbiter, which had subsequently re-entered the magnetosphere on the dusk side. As the external pressure increases, so too does the total field magnitude at Galileo (in particular the theta and phi components). In addition a transition from a mainly lagging field configuration prior to the compression to a strongly leading one after the onset of the event is seen, implying externally triggered super-corotation of the magnetosphere due to conservation of angular momentum. Heating of the magnetospheric plasma can be seen clearly as a pronounced increase in particle flux as measured by the EPD instrument aboard Galileo. The behavior and response time of the system appears to be comparable to that predicted by recent theoretical modeling of the Jovian magnetosphere-ionosphere coupling system.

The Cassini fly-by of Jupiter occurred at a time of solar maximum, and as a consequence, the in-situ measurements taken in the Solar Wind upstream of the planet, reveal numerous Interplanetary Coronal Mass Ejections (ICMEs). A fortuitous alignment of the planets allowed us to trace these events back to observations taken at the Earth. In particular one event observed by Cassini is shown to be a Merged Interaction Region (MIR), created from the coalescence of multiple ICMEs between 1 and 5 AU. We examine results from a one dimensional Magneto-hydrodynamic (MHD) simulation of the Solar Wind at Earth propagated out to Cassini and compare with the in-situ data taken. It is found that by integrating along the nominal Parker Spiral field we can to some extent, correct for the changing angular offset between the two points of observation by obtaining a fractional increase or decrease in the propagation time of the events observed. The results of this MHD simulation are then allowed to propagate further to the planet allowing comparisons to be made between the state of the Solar Wind and remote observations of the planetary aurorae that were taken simultaneously.

The dynamics and field structure of the Jovian magnetosphere are dominated by the presence of a vast current carrying plasma sheet centred about the magnetic equator. The magnetic field due to the predominantly azimuthal current carried by this plasma sheet, extends the field lines of the middle magnetosphere radially outward producing the elongated structure that is characteristic of the system. We employ magnetic field data gathered by the Galileo spacecraft in order to investigate the structure of the plasma sheet with radial range. The departure of the sheet from the equatorial plane is found to inhibit accurate measurements of its thickness past 30RJ, although models of the plasma sheet motion can be employed to correct somewhat for this effect.

Multi-instrument studies of the dayside magnetosphere and the cusp have proven to be an excellent way to study the direct coupling of the solar wind-magnetosphere-ionosphere system. On 4 October 2002 there was an excellent and rare conjunction of spacebourne instrumentation monitoring the dayside magnetosphere and ground-based instruments in the Scandinavian sector below. The IMAGE spacecraft passed over the northern polar cap during the interval, Geotail was in the vicinity of the postnoon magnetopause, and CLUSTER traversed the cusp. EISCAT and ESR were operating in a CP4-type mode, providing simultaneous measurements of electron densities and temperatures over a range of latitudes through the auroral zone and well into the polar cap. The density and temperature data will be examined in the context of the large-scale convection velocities measured by the CUTLASS HF radars, the global ultraviolet auroral emissions, and the in situ magnetospheric measurements. The results from this comparative analysis of magnetospheric sampling at a variety of altitudes will be discussed.

In January and early February 2002, orbital manoeuvres were in progress to alter the Cluster constellation size. At times, the four Cluster spacecraft were arranged along a line, rather than in the more usual equilateral tetrahedron as they crossed the magnetopause. The configuration allows simultaneous observations at various distances from the magnetopause of any magnetopause boundary layer and of flux transfer events, as well as the consequences of any in- or outward magnetopause motion. Such a configuration existed on the 25th January 2002 as the spacecraft approached the magnetopause after passing through the northern high latitude cusp travelling outbound. The PEACE electron spectrometers on the four spacecraft all observed a series of transient bursts of magnetosheath-like plasma. One such event, at ~10:08 UT is accompanied on some of the spacecraft by a signature in the magnetic field similar to a crater-type Flux Transfer Event. PEACE and supporting data from this event are presented, and the evidence for pressure pulse, FTE or some other origin is discussed.

When modelling the evolution of the open magnetic flux threading the solar surface, and the open solar flux that results, two factors are critical for each newly-emerged bipolar magnetic region (BMR), namely it's latitude and the tilt angle of the line connecting the centres of the two opposite polarity regions. The variation of the former throughout the solar cycle is given by the well-known butterfly diagram, however the behaviour of the latter is not so clearly defined. Using magnetogram observations of BMR's, a systematic variation of average tilt angle with heliographic latitude, and thus with solar phase, has been reported and used in several modelling studies. However, using observations of sunspot pairs no such variation is apparent. We here investigate various subsets of the tilt angle data from sunspots in an attempt to reconcile and understand these apparently contradictory results.

This presentation will explore the role of fractal turbulence in allowing the creation and maintenance of large-scale reconnection sites on the dayside magnetopause.

The EISCAT incoherent radar system, which is collocated with the EISCAT heating facility, is used to diagnose the ionosphere while heating experiments are conducted. Ionospheric modification produces characteristic signatures in the radar data. These include the ‘ion-line overshoot’, which is identified by an increase, and subsequent decrease, in the apparent electron concentration near the reflection height for O-mode-polarized radio waves. Data are presented that indicate a gradual decrease in the altitude at which the ion-line overshoot occurs. The variation in the altitude is consistent with a two-stage process, characterized by steady descent of the feature followed by stabilization.

It has long been accepted that the azimuthal scale size of ULF waves plays an important role in the apparent magnitude of the wave signature as observed in ground-based magnetometer data. This leads to large-scale waves, generally those generated externally to the magnetosphere, being far more easily detected on the ground than those small-scale waves which are generally generated internally to the magnetosphere via wave-particle interactions. Experimental demonstration of this phenomenon has proved to be difficult, however. Here the HF radar artificial backscatter technique is exploited to provide high quality observations of the ionospheric ULF wave electric field over Tromsø, which can then be readily compared with data from the Tromsø ground magnetometer. This technique provides the high resolution measurements over the wide variety of scale sizes which are required to verify the theory. The technique can also measure the scale sizes of the waves in both latitude and longitude. In addition, the EISCAT radar at Tromsø provides information on additional parameters which influence the magnitude of the ground magnetometer signature, such as the ionospheric conductivities.

Data from IRIS and other Riometers have been used to investigate the dynamics of solar energetic protons (1-500 MeV) during the geomagnetic storm and polar cap absorption (PCA) event of the 14-17 July 2000 (the 'Bastille Day' event). The influence of geomagnetic position on cosmic noise absorption is presented with maximum levels occurring in the cusp and polar cap region. A magnetospheric particle-tracing model is used to investigate the motion of different energies of protons through the geomagnetic field ending at the locations of a number of Riometer stations (e.g. IRIS, and the SGO and CANOPUS chains). With the help of the model energy filtering will be used to estimate the energy levels of precipitating protons.

We present a multi-instrument study of a magnetospheric substorm event that occurred on 1st September 2002. Cluster data from the Fluxgate Magnetometer (FGM), Plasma Electron and Current Experiment (PEACE), Cluster Ion Experiment (CIS) and Research with Adaptive Particle Imaging Detectors (RAPID) instruments are considered in combination with the ground-based International Monitor for Auroral Geomagnetic Effects (IMAGE magnetometer array) and Super Dual Auroral Radar Network (SuperDARN) instruments. The simultaneous observations of the magnetospheric substorm event in both the ionosphere and magnetotail regions will be presented.

The imminent return of spacecraft to the planet Mercury has sparked a new drive in efforts to model its magnetosphere. Here we present a brief summary of the data returned by the Mariner 10 magnetic fields experiment, and show how the small dipole moment, the absence of a ring current and the differences in boundary conditions are likely to affect the magnetosphere of Mercury. We also outline the work that is being carried out to modify existing models of the Earth's magnetosphere to investigate their applicability to Mercury. We pay particular attention to the contributions from the magnetopause and tail currents.

The Extreme Ultraviolet Imager (EUV) on board the IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) satellite observes the global distribution of He+ in the plasmasphere from resonantly scattered solar radiation at 30.4nm. We use a coupled thermosphere-ionosphere-plasmasphere model (CTIP) to solve the equations of continuity, momentum and energy balance for O+, H+ and more importantly for this investigation, He+. In this presentation, model results will be compared to observations made by the EUV imager.

The radars of the EISCAT Scientific Association are, and have been for most of the last twenty years, the pre-eminent instruments of their type in the World and form a core element of the cost-effective geophysical research environment in northern Scandinavia.

In today’s climate, where funding agencies apparently believe that merely continuing to produce World-class science is unworthy of future funding, the Association must make hard decisions concerning its future.

Over the past two years, a small group has been working to define a vision of the EISCAT future. The work is still in progress, but the presentation will outline its main elements, as well as providing contextual information on the current status of the facilities.

A survey of Ulysses magnetometer data has been carried out from launch (Oct 1990) to the second northern polar pass (Oct 2001) cataloguing magnetic cloud (MC) signatures, i.e. a smooth field rotation and enhanced field magnitude. After confirming that each of these events was a true MC by checking for a low proton temperature signature, it was possible to fit a constant a, force-free flux rope model to each event in order to determine parameters describing its global magnetic flied configuration. The survey has shown that associated with many MC field rotations there is a second, less well-defined, rotation. Usually this rotation is so poorly defined that it is impossible to fit the flux rope model to it. However, in two specific cases, presented here, it has been possible to produce good model fits to both rotations. This gives insight into the chirality and relative orientations of the two flux ropes. The results suggest that the two rotations are part of the same, deformed, rope which the spacecraft has passed through at two different points.

The relationship between velocities of absorption patches and moving E- and F-region structures is studied employing data from IRIS, CUTLASS and STARE radars.

One event of postnoon measurements when both 10- and 144-MHz E-region echoes were seen as narrow bands (150-200 km) of strong backscatter at short distances of < 600 km is studied in detail. During the period under study, the CUTLASS radar observed both E- and F-region echoes that were moving in range, which have resulted in appearance of the quite remarkable W-like structures in the range-time-intensity plots. The STARE radar observed the similar structures in the E-region scatter as well.

We relate the velocity of regions with enhanced absorption with the velocity of coherent scatter from 1- and 15-m waves. By considering the data from the IRIS beams that were not affected by the scintillations we show that the absorption patches are moving with the velocity that is consistent with that observed by the CUTLASS and STARE radars.

A numerical implementation of the Cowley-Lockwood conceptual model has been developed to quantitatively predict ionospheric convection in response to time-dependent magnetopause reconnection. This model has now been extended to map the variations in ion temperatures. The convection enhancement is studied using the model response in ion temperature and the response to reconnection rate variations is studied for different reconnection scenarios. The expansion velocities derived by both threshold and cross-correlation methods are discussed. This work will go some way to explaining the apparently contradictory reports of an expanding convection pattern and quasi-instantaneous enhancement of the convection pattern in response to reconnection rate variations.

The presence of signatures in the upstream solar wind and magnetic field data can be coupled to observations in the proton aurora measured by a range of ground-based and satellite-borne instruments. An event on the 26 November 2000 showed strong signatures in the solar wind and subsequent proton precipitation. The event, accompanied by an increase in solar wind pressure and change in Bz polarity of the IMF, resulted in auroral structures that suggested a Travelling Convection Vortex (TCV). The Northern hemisphere SuperDARN radars observed a dayside vortical flow pattern, and a realignment of the equipotential flow lines, which may be related to the TCV.

A three dimensional, ionospheric ray tracing model (Jones3D) has been used to study traveling ionospheric disturbances caused by gravity waves. The ground backscatter power from the model in the presence of a TID was compared with an event observed in CUTLASS data on December 9, 1997. Some recent results of this study will be presented.

We propose a minimal model for the evolution of the global dynamical state of the magnetotail during the substorm, involving only three simple rules. Rather than concentrate on the physical nature of the substorm instability, we consider the instability in a more general sense. The substorm is modelled as an integrate-and-fire process in which integrated solar wind power input during the substorm growth phase is eventually released in whole or in part by a firing mechanism at substorm onset. We propose that this nonlinear property is because the magnetosphere is prevented from moving to the lowest energy state appropriate to the prevailing solar wind boundary condition by some configurational constraint involving the magnetic field. When this configurational constraint is overcome, a substorm occurs and the magnetosphere moves towards the minimum energy state appropriate for that time. When driven by a real solar wind power input, the minimal substorm model produces a probability distribution of times between substorm onsets that compares favourably with the distribution of 1001 inter-substorm intervals found by Borovsky et al. from observation. We discuss these results and propose possible further tests of the model.

SIF is a Southampton University (SU) Ð University College London (UCL) collaboration which is a PPARC funded project, awarded from the National ground-based facility committee for geophysics. The platform consists of a High Throughput Imaging Echelle Spectrograph, HiTIES, two photometers and a narrow angle auroral imager. The spectrograph has a mosaic filter; each of the three spectral panels are centred over/near important spectral features: Hbeta (486.1nm), N2+(470.9nm), N2+(465.2nm). Thus, allowing studies of proton and electron aurorae. The platform has been successfully deployed in Svalbard. Current operating modes will be discussed as well as web-based data availability and accessibility and results from recent campaigns.