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  • Journal article
    Eastwood JP, Sibeck DG, Slavin JA, Lavraud B, Lucek EA, Balogh A, Dandouras Iet al., 2006,

    Observations of flux ropes and X-lines in the near earth magnetotail

    , European Space Agency, (Special Publication) ESA SP, Pages: 59-66, ISSN: 0379-6566

    Magnetic reconnection in the Earth's magnetotail plays a key role in controlling the dynamics of the Earth's magnetosphere. Recent results based on Cluster multi-spacecraft analysis have raised important questions about the traditional interpretation of reconnection-associated phenomena observed by single spacecraft. Cluster has shown that observations conventionally interpreted as a single X-line can correspond to multiple X-line structure [1]. Single point observations cannot distinguish between these two possibilities, and previous interpretations have invoked the simpler picture. This case study is put into a wider context by examining the plasma dynamics following this particular event. Within this picture, one can make the hypothesis that further loop-like structures - small flux ropes - ought to be observed in conjunction with this event. We present such evidence here, and in particular use the curlometer technique to analyse the observations.
  • Book chapter
    Zong QG, Fritz TA, Zhang H, Fu SY, Zhou XZ, Goldstein ML, Daly PW, Reme H, Balogh A, Fazakerley ANet al., 2006,

    The magnetospheric cusp: Structure and dynamics

    , Advances in Geosciences: Volume 2: Solar Terrestrial (ST), Pages: 173-189

    Understanding the polar cusps is essential for a thorough understanding of the entire physics of the magnetosphere, and of the dynamical interaction between the solar wind and any planetary magnetosphere. Energetic electrons are unique to fully assess magnetic Field-Line topology and thus should be able to clearly delineate regions of open and closed magnetic field lines in the High-Latitude regions and contributed crucially to understanding and resolving an internal debate going on between groups measuring only the lower energy (<20 keV) plasma. Energetic electrons with high and stable flux were observed in the high latitude boundary/cusp region when the Interplanetary Magnetic Field (IMF) had a predominate positive Bz component. With measurements at larger separations and more coordination of multiple satellite measurements for particular cusp crossings it will become more evident what the true nature of the cusp is and what roles the cusp plays. The boundary normal, velocity and timing analysis obtained by all four Cluster spacecraft indicates that the multiple cusp phenomena are most likely caused by the oscillation of a single northern cusp which was shifted back and forth. Cusp oscillations with a period of ˜20min are observed by Cluster in the High-Latitude region, whilst the Cold-Dense plasma with fluctuations (20-Min period) are observed in the Dusk-Side of the tail plasma sheet by Geotail. This is consistent with the idea that the high latitude reconnection during northward IMF is the responsible mechanism for the formation of the Cold-Dense plasma sheet.
  • Conference paper
    Pu ZY, Wang J, Dunlop MW, Zhang XG, Wei Y, Zhou XZ, Fu SY, Xiao CJ, Zong QG, Liu ZX, Carr C, Perry C, Reme H, Dandouras I, Fazakerley A, Daly P, Pitout F, Davies J, Shen C, Laakso H, Escoubet P, Owen CJ, Bogdanova Y, Taylor MGGTet al., 2006,

    Cluster and TC1 five point observations of an FTE on jan. 4, 2005: A preliminary study

    , Pages: 171-179, ISSN: 0379-6566

    Observations of an FTE signature at the dayside magnetopause are reported, which is consecutively observed on Jan.4, 2005 by each of five spacecraft comprising the Double Star TC1 spacecraft and the Cluster quartet, while the spacecraft were traversing through the northern-dusk magnetopause. The GSE locations of Cluster and TC1 were ∼ (3.91, 12.03, 5.01) RE and (4.33, 12.50, 1.93) RE (GSE), respectively. The event occurred as a magnetosheath FTE at the first Cluster spacecraft at about 07:13 UT on 04 01 2004 and crossed each of the others within 2 minutes. The spatial separations between the Cluster spacecraft were of the order of 200 km and the relative TC1 location was at ΔX∼ 0.42RE, ΔY∼0.47RE, and ΔZ∼ 3.08RE. The TC1 signature occurred about 110s after Cluster. deHoffmann- Teller (H-T) analysis of the signatures implies that the associated flux ropes observed by Cluster and TC1 were moving with similar velocities eastward and northward, consistent with the polarity for the observed FTEs and the spacecraft locations. The orientation of the flux rope can also be computed and is found to be similar at each spacecraft. Reconstruction of the flux rope signature suggests that they contained approximately equal amounts of magnetic flux. The 3-D distributions of thermal ions in the two FTEs were also similar. The distance of TC1 perpendicular to the plane containing the axis of flux rope observed by Cluster and its H-T velocity is much smaller than the cross-section dimension of the flux ropes observed by both Cluster and TC1. These findings strongly suggest that Cluster and TC1 encountered the magnetosheath branch of the same flux tube at two different positions along its length and this is borne out by computation of the expected time delay between the spacecraft based on the estimated orientation of the tube. Four-spacecraft timing is used to confirm the H-T velocity calculation. Several approaches are used to estimate the axis orient
  • Conference paper
    Georgescu E, Vaith H, Fornacon KH, Auster U, Balogh A, Carr C, Chutter M, Dunlop M, Foerster M, Glassmeier KH, Gloag J, Paschmann G, Quinn J, Torbert Ret al., 2006,

    Use of EDI time-of-flight data for FGM calibration check on cluster

    , Pages: 535-541, ISSN: 0379-6566

    The four Cluster satellites launched in summer 2000 carry flux-gate magnetometers (FGM), which measure the magnetic field vector. The satellites also carry electron drift instruments (EDI) that measure the gyration time of electrons perpendicular to the magnetic field. The gyration time is related through a universal constant to the magnetic field magnitude and is hence an absolute measure of it. The knowledge of the field magnitude can be used to verify the magnetometer calibration or to carry out a scalar calibration of FGM, similarly to near-Earth space missions where proton magnetometers provide this information. The resulting increased accuracy of the magnetic field measurement on the four spacecraft enhances the value of the multipoint measurements on Cluster by reducing the uncertainties in deriving the differential quantities such as the curl of the magnetic field. In this paper the errors in the measurements made by FGM and EDI are discussed and a comparison of the measurements is presented. The conclusion is that the absolute error of the magnetic field measurement is about 0.1 nT for fields below 100 nT and less than 0.1% for fields above.
  • Conference paper
    Marchaudon A, Owen CJ, Bosqued JM, Fear RC, Fazakerley AN, Dunlop MW, Lahiff AD, Carr C, Balogh A, Lindqvist PA, Rème Het al., 2006,

    Simultaneous double star and cluster ftes observations on the dawnside flank of the magnetosphere

    , Pages: 163-170, ISSN: 0379-6566

    We present Cluster and Double Star-1 (TC-1) observations from a close magnetic conjunction on May 8, 2004. The five spacecraft were on the dawnside flank of the magnetosphere, with TC-1 located near the equatorial plane and Cluster at higher geographic latitudes in the southern hemisphere. TC-1, at its apogee, skimmed the magnetopause for almost 8 hours (between 08:00-16:00 UT). Flux Transfer Events (FTEs), moving southward/tailward from the reconnection site, were observed by TC-1 throughout almost all of the period. Cluster, travelling on a mainly dawn-dusk trajectory, crossed the magnetopause at around 10:30 UT in the same Magnetic Local Time (MLT) sector as TC-1 and remained close to the magnetopause boundary layer in the southern hemisphere. The four Cluster spacecraft observed FTEs for a period of 6.5 hours between 07:30 and 14:00 UT. From the properties of these FTEs, the reconnection site was located northward of both TC-1 and Cluster on the dawn flank of the magnetosphere. Reconnection occurred between draped magnetosheath and closed magnetospheric field lines. Despite variable interplanetary magnetic field (IMF) conditions and IMF-B z turnings, the IMF clock-angle remained greater than 70° and the location site appeared to remain relatively stable in position during the whole period. This result is in agreement with previous studies which reported that the dayside reconnection remained active for an IMF clock-angle greater than 70°. The simultaneous observation of FTEs at both Cluster and TC-1, separated by 2 hours in MLT, implies that the reconnection site on the magnetopause must have been extended over several hours in MLT. This event has been already presented in more details in [1].
  • Conference paper
    Cornilleau-Wehrlin N, Attié D, Belraont G, Rezeau L, Robert P, Alleyne HSC, Yearby K, Balogh A, Carr Cet al., 2006,

    Comparison of ulf waves at magnetopause crossings at different latitudes, as seen by the cluster and double star staff experiments

    , Pages: 191-197, ISSN: 0379-6566

    Strong ULF wave activity has been observed at magnetopause crossings since a long time. Those turbulent like waves are possibly one of the contributors to particle penetration from the Solar Wind to the Magnetosphere through the magnetopause. STAFF Wave experiments onboard Cluster and Double Star TC1 spacecraft permit the comparison of those waves during coordinated crossings, at the same local time, but at different latitude, the TC1 Double Star orbit being nearly equatorial and the Cluster one polar. From a first analysis of simultaneous Cluster and DSP data sets in the first half of year 2004, 21 coordinated magnetopause crossings have been identified, i.e. within less than 3 hours, out of which 16 are within one hour time delay. Some characteristics of the ULF wave data in the vicinity of these crossings are compared, as wave power and frequency spectra power law. Similarities and differences are discussed at the light of solar wind parameters, latitude, local time or time delay between the crossings. These results first confirm the relation between the solar wind pressure and the ULF wave power. They indicate that in most of the cases, the wave power measured by Double Star is stronger than the one measured by the Cluster spacecraft., whereas no local time dependence has been found. If those first results were to be confirmed, it could imply a predominant role of the equatorial plane in the solar wind/ magnetosphere coupling via ULF wave turbulence, with no preference for the sub-solar region.
  • Conference paper
    Dunlop MW, Taylor MGGT, Davies JA, Pu Z, Fazakerley AN, Owen CJ, Bogdanova YV, Pitout F, Laakso H, Zong QG, Shen C, Nykyri K, Lavraud B, Milan SE, Liu ZX, Escoubet CP, Rème H, Carr CM, Phan TD, Lockwood M, Sonnerup Bet al., 2006,

    Comparative Cluster/Double Star observations of the high and low latitude dayside magnetopause

    , Pages: 393-400, ISSN: 0379-6566

    The launch of the Double Star mission has provided the opportunity to monitor events at distinct locations on the dayside magnetopause, in coordination with the quartet of Cluster spacecraft. We present results of two such coordinated studies. In the first, 6 April 2004, both Cluster and the Double Star TC-1 spacecraft were on outbound transits through the dawn-side magnetosphere. Cluster observed northward moving FTEs with +/- polarity, whereas TC-1 saw -/+ polarity FTEs. The strength, motion and occurrence of the FTE signatures changes somewhat according to changes in IMF clock angle. These observations are consistent with ongoing reconnection on the dayside magnetopause, resulting in a series of flux transfer events (FTEs) seen both at Cluster and TC-1. The observed polarity and motion of each FTE signature advocates the existence of an active reconnection region consistently located between the positions of Cluster and TC-1, lying north and south of the reconnection line, respectively. This scenario is supported by the application of a model, designed to track flux tube motion, to conditions appropriate for the prevailing interplanetary conditions. The results from the model confirm the observational evidence that the low-latitude FTE dynamics is sensitive to changes in convected upstream conditions. In particular, changing the interplanetary magnetic field (IMF) clock angle in the model predicts that TC-1 should miss the resulting FTEs more often than Cluster, as is observed. For the second conjunction, on the 4 Jan 2005, the Cluster and TC-1 spacecraft all exited the dusk-side magnetosphere almost simultaneously, with TC-1 lying almost equatorial and Cluster at northern latitudes at about 4 RE from TC-1. The spacecraft traverse the magnetopause during a strong reversal in the IMF from northward to southward and a number of magnetosheath FTE signatures are subsequently observed. One coordinated FTE, studied in detail by Pu et al, [this issue], carries and inflo
  • Conference paper
    Wild JA, Milan SE, Davies JA, Cowley SWH, Dunlop MW, Owen CJ, Bosqued JM, Lester M, Balogh A, Carr CM, Fazakerley AN, Rème Het al., 2006,

    Space and ground-based investigations of dayside reconnections: Cluster, double star and superdarn observations

    , Pages: 199-208, ISSN: 0379-6566

    In this paper, we present an overview of several investigations that have exploited Cluster, Double Star and SuperDARN radar data in order to scrutinise the coupling of the solar wind, magnetosphere and ionosphere. The studies introduced have drawn upon simultaneous space- and ground-based data in order to overcome the inherent shortcomings of the in situ (space-based) and remotely-sensed (ground-based) measurement techniques. In particular, we shall highlight the results of studies that investigate the dynamics arising from magnetic reconnection at the dayside magnetopause and the resulting ionospheric responses.
  • Conference paper
    Milan SE, Wild JA, Hubert B, Carr CM, Lucek EA, Bosqued JM, Watermann JF, Slavin JAet al., 2006,

    Flux transport and tail dynamics during a prolonged substorm interval

    , Pages: 261-267, ISSN: 0379-6566

    We present multi-point observations of a substorm which took place on 29 August 2004. The near-Earth magnetotail dynamics were observed by Cluster C1 and Double Star TC1, in conjunction with observations of the Northern Hemisphere ionospheric convection flow from the Super Dual Auroral Radar Network (SuperDARN), of the Southern Hemisphere auroral morphology from the Wideband Imaging Camera of the Far Ultraviolet instrument onboard the Imager for Magnetopause-to-Aurora Global Exploration spacecraft (IMAGE FUV/WIC), and of ionospheric substorm currents from the Greenland magnetometer chain. Following the substorm growth phase, expansion phase onset results in the closure of open magnetic flux for 3 hours, prolonged by continued creation of open flux at the dayside. The 3-hour duration of the substorm was punctuated by 5 dipolarizations which we interpret as individual bursts of reconnection, each closing ∼0.125 GWb of flux. Associated with each dipolarization were auroral enhancements, convection enhancements and a step-wise poleward progression of the substorm current wedge. We derive the amount of open flux in the magnetosphere from observations of the ionospheric polar cap, along with the corresponding rates of dayside and night-side reconnection. From these we can model the changing length of the magnetotail and variations in its radius, flaring, and lobe field strength during the course of the growth and expansion phases of the substorm. Despite the simplicity of this modeling, we demonstrate good agreement between predicted lobe field strength and the observations of Cluster.
  • Conference paper
    Shi JK, Zhang TL, Cheng ZW, Liu ZX, Nakamura R, Carr C, Balogh Aet al., 2006,

    Field aligned current observed by cluster

    , Pages: 417-420, ISSN: 0379-6566

    In this study, features of the Field Aligned Currents (FACs) distribution in the plasma sheet boundary layer are investigated. The current is calculated with the 4-point measurement of FluxGate Magnetometer (FGM) on board the Cluster in the period of July to October 2001. There are 172 FAC cases/events chosen for statistics. The results show that spatial distribution of the FAC has asymmetry in several aspects. The FACs occurrence is mainly Earthward in dawn side and is mainly tailward in dusk side. The FACs occurrence also has south-north hemisphere asymmetry.
  • Conference paper
    Taylor MGGT, Lavraud B, Thomsen MF, Fazakerley AN, Dunlop MW, Davies JA, Escoubet CP, Laakso H, Khan H, Masson A, Opgenoorth HJ, Friedel RH, Rème H, Carr CM, Zhang TL, Lucek EAet al., 2006,

    Multi-satellite observations of the near earth plasma sheet and flank magnetopause: Response to the 5 <sup>TH</sup> December 2004 CME

    , Pages: 421-427, ISSN: 0379-6566

    On 5 th December 2004 after an extended period of weakly northward/dawnward directed interplanetary magnetic field (IMF), a coronal mass ejection (CME) impacted the Earth's magnetosphere. The interplanetary magnetic cloud was characterised by an extended (> 12 hours) period of northward IMF (although initially with a clock angle ∼ 45 degrees) and a rapid solar wind dynamic pressure increase from 1-9 nPa. During this time numerous magnetospheric spacecraft were operational: The ESA Cluster spacecraft were inbound from the southern hemisphere, dusk-flank magnetosheath; on the same flank, the CNSA/ESA TC-1 spacecraft was skimming the magnetopause; closer to the Earth, the CNSA/ESA TC-2 spacecraft was in the northern hemisphere lobe/mantle/plasma sheet boundary region at an altitude of about 5 Earth Radii and we also made use of multipoint measurements from the LANL geosynchronous spacecraft. From previous studies, the impinging Solar wind/IMF conditions characterising this event (northward IMF and compressed magnetosphere) are conducive to the delivery of cold dense plasma sheet (CDPS) material into the near-Earth region. In this case study we investigate the possible source and means of formation of this material and put it in context with other recent CDPS studies.
  • Conference paper
    Gloag JM, Carr C, Forte B, Lucek EAet al., 2006,

    The status of cluster FGM data submissions to the CAA

    , Pages: 461-464, ISSN: 0379-6566

    The FGM contribution to the Cluster Active Archive consists of 3 main magnetic field data products and a set of auxiliary data products. The three primary magnetic field data products contain the magnetic field in GSE coordinates at three different time resolutions. The first data product has full resolution data which can be at 22Hz or 67Hz depending on the mode of the instrument. The second data product has data at 5Hz and the third data product at spin resolution. All data products are validated for scientific use. Presented here is an outline of the procedure used to create these data products. A description of the calibration techniques used to produce the required calibration files is also set out as this forms a major part of the production procedure. In addition the present status of data products submitted to the CAA is presented along with a projection of what will be submitted in the near future.
  • Conference paper
    Horbury T, Louarn P, Fujimoto M, Baumjohann W, Blomberg LG, Barabash S, Canu P, Glassmeier KH, Koskinen H, Nakamura R, Owen C, Pulkkinen T, Roux A, Sauvaud J-A, Schwartz SJ, Svenes K, Vaivads Aet al., 2006,

    Cross-Scale: a multi-spacecraft mission to study cross-scale coupling in space plasmas
  • Journal article
    Masood W, Schwartz SJ, Maksimovic M, Fazakerley ANet al., 2006,

    Electron velocity distribution and lion roars in the magnetosheath

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 1725-1735, ISSN: 0992-7689
  • Journal article
    Sung S-K, Kim K-H, Lee D-H, Takahashi K, Cattell CA, Andre M, Khotyaintsev YV, Balogh Aet al., 2006,

    Simultaneous ground-based and satellite observations of Pc5 geomagnetic pulsations:: A case study using multipoint measurements

    , EARTH PLANETS AND SPACE, Vol: 58, Pages: 873-883, ISSN: 1880-5981
  • Journal article
    Bunce EJ, Cowley SWH, Jackman CM, Clarke JT, Crary FJ, Dougherty MKet al., 2006,

    Cassini Observations of the Interplanetary Medium Upstream of Saturn and their relation of the Hubble Space Telescope Aurora Data

    , Adv. Space Res., Vol: 38, Pages: 806-814
  • Journal article
    Haigh JD, Roscoe HK, 2006,

    Solar influences on polar modes of variability

    , Meteorologische Zeitschrift, Vol: 15, Pages: 371-378
  • Conference paper
    Asano Y, Nakamura R, Runov A, Baumjohann W, McIlwain C, Paschmann G, Quinn J, Alexeev I, Dewhurst JP, Owen CJ, Fazakerley AN, Balogh A, Reme H, Klecker Bet al., 2006,

    Detailed analysis of low-energy electron streaming in the near-Earth neutral line region during a substorm

    , Conference on Reconnection at Sun and in Magnetospheres held at the 35th COSPAR General Assembly, Publisher: ELSEVIER SCIENCE LTD, Pages: 1382-1387, ISSN: 0273-1177
  • Journal article
    Nilsson H, Waara M, Arvelius S, Marghitu O, Bouhram M, Hobara Y, Yamauchi M, Lundin R, Reme H, Sauvaud J-A, Dandouras I, Balogh A, Kistler LM, Klecker B, Carlson CW, Bavassano-Cattaneo MB, Korth Aet al., 2006,

    Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster:: a statistical study

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 1099-1112, ISSN: 0992-7689
  • Journal article
    Balan N, Alleyne H, Walker S, Reme H, Decreau PME, Balogh A, Andre M, Fazakerley AN, Cornilleau-Wehrlin N, Gurnett D, Fraenz Met al., 2006,

    Cluster observations of a structured magnetospheric cusp

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 1015-1027, ISSN: 0992-7689
  • Journal article
    Galand M, Bhardwaj A, Chakrabarti S, 2006,

    On the importance of the cross-body approach in planetary aeronomy

    , Advances in Geosciences, Vol: Volume 2: Solar Terrestrial, Pages: 239-248, ISSN: 1680-7340
  • Journal article
    Nykyri K, Otto A, Lavraud B, Mouikis C, Kistler LM, Balogh A, Reme Het al., 2006,

    Cluster observations of reconnection due to the Kelvin-Helmholtz instability at the dawnside magnetospheric flank

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 2619-2643, ISSN: 0992-7689
  • Conference paper
    Carr C, Brown P, Zhang TL, Aydogar O, Magnes W, Auster U, Balogh A, Beek T, Eichelberger H, Fornacon K-H, Georgescu E, Gloag J, Liao H, Ludlam M, Nakamura R, O'Brien H, Oddy T, Richter Iet al., 2006,

    The Double Star magnetic field investigation: Overview of instrument performance and initial results

    , 35th COSPAR Scientific Assembly, Publisher: ELSEVIER SCIENCE LTD, Pages: 1828-1833, ISSN: 0273-1177
  • Conference paper
    Russell JE, Harries JE, Clearbaux N, 2006,

    Geostationary Earth Radiation Budget (GERB): Validation results

    , 3rd MSG RAO Workshop, Publisher: ESA PUBLICATIONS DIVISION C/O ESTEC, Pages: 5-+, ISSN: 0379-6566
  • Conference paper
    Scuffham J, Giampieri G, Balogh A, 2006,

    BepiColombo measurements of Mercury's internal field

    , 35th COSPAR Scientific Assembly, Publisher: ELSEVIER SCIENCE LTD, Pages: 610-+, ISSN: 0273-1177
  • Conference paper
    Németh Z, Facskó G, Erdos G, Balogh Aet al., 2006,

    Plasma mixing as a cause of solar wind magnetic field variations

    , 35th COSPAR Scientific Assembly, Publisher: ELSEVIER SCIENCE LTD, Pages: 467-472, ISSN: 0273-1177
  • Journal article
    Muller-Wodarg IC, Mendillo M, Yelle RV, Aylward ADet al., 2006,

    A global circulation model of Saturns thermosphere

    , ICARUS, Vol: 180, Pages: 147-160, ISSN: 0019-1035
  • Journal article
    Amm O, Nakamura R, Frey HU, Ogawa Y, Kubyshkina M, Balogh A, Reme Het al., 2006,

    Substorm topology in the ionosphere and magnetosphere during a flux rope event in the magnetotail

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 735-750, ISSN: 0992-7689
  • Journal article
    Longmore M, Schwartz SJ, Lucek EA, 2006,

    Rotation of the magnetic field in Earth's magnetosheath by bulk magnetosheath plasma flow

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 339-354, ISSN: 0992-7689
  • Journal article
    Robertson SC, Lanchester BS, Galand M, Lummerzheim D, Stockton-Chalk AB, Aylward AD, Furniss I, Baumgardner Jet al., 2006,

    First ground-based optical analysis of H<sub>β</sub> Doppler profiles close to local noon in the cusp

    , ANNALES GEOPHYSICAE, Vol: 24, Pages: 2543-2552, ISSN: 0992-7689

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