Multiple spacecraft observations of interplanetary shocks: Four spacecraft determination of shock normals

Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

doi:10.1029/ja088ia06p04739

Cited by 231 publications

(229 citation statements)

References 5 publications

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“…Events of this nature have been reported by Russell et al (1983), who presented observations of interplanetary shocks using the ISEE-1, 2, and 3 spacecraft, together with either IMP-8 or Prognoz-7 as the fourth. By analysing the time differences in relation to the spatial separations, the authors were able to determine the normals to the shocks studied.…”

Section: Introductionmentioning

confidence: 97%

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A comparison of wave mode identification techniques

Walker

Sahraoui²,

Balikhin

et al. 2004

Ann. Geophys.

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Abstract. The four point measurements available from the Cluster mission enable spatiotemporal effects in data sets to be resolved. One application of these multipoint measurements is the determination of the wave vectors and hence the identification of wave modes that exist within the plasma. Prior to multi-satellite missions, wave identification techniques were based upon the interpretation of observational data using theoretically defined relations. However, such techniques are limited by the quality of the data and the type of plasma model employed. With multipoint measurements, wave modes can be identified and their wave directions determined purely from the available observations. This paper takes two such methods, a phase differencing technique and k-filtering and compares their results. It is shown that both methods can resolve the k vector for the dominant mirror mode present in the data. The phase differencing method shows that the nature of the wave environment is constantly changing and as such both methods result in an average picture of the wave environment in the period analysed. The k-filtering method is able to identify other modes that are present.

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Section: Introductionmentioning

confidence: 97%

“…This enables the projection of the wave vector to be determined along three independent baselines (Balikhin et al, 2000;Bates et al, 2001;Balikhin et al, 2003). It is then possible to reconstruct the original k using a matrix inversion technique similar to that used by Russell et al (1983) by solving the equation…”

Section: Phase Differencing Methodsmentioning

confidence: 99%

A comparison of wave mode identification techniques

Walker

Sahraoui²,

Balikhin

et al. 2004

Ann. Geophys.

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show abstract

“…In this approach (Russell et al, 1983) we put A 1 =A 2 =A 3 =0 so that the magnetopause velocity is constant during the event: V (t)=A 0 . Equation (4) then becomes…”

Section: Constant Velocity Approach: Cvamentioning

confidence: 99%

“…A method, based on timing alone, for determination of the orientation, speed and thickness of a discontinuity moving past four observing spacecraft was first presented by Russell et al (1983), who applied it to interplanetary shocks. Their method uses the measured time differences between the passage of the discontinuity over the spacecraft, along with the known separation vectors between them and, to obtain the discontinuity thickness, the duration of each crossing.…”

Section: Introductionmentioning

confidence: 99%

Four-spacecraft determination of magnetopause orientation, motion and thickness: comparison with results from single-spacecraft methods

et al. 2004

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Abstract. In this paper, we use Cluster data from one magnetopause event on 5 July 2001 to compare predictions from various methods for determination of the velocity, orientation, and thickness of the magnetopause current layer. We employ established as well as new multi-spacecraft techniques, in which time differences between the crossings by the four spacecraft, along with the duration of each crossing, are used to calculate magnetopause speed, normal vector, and width. The timing is based on data from either the Cluster Magnetic Field Experiment (FGM) or the Electric Field Experiment (EFW) instruments. The multi-spacecraft results are compared with those derived from various singlespacecraft techniques, including minimum-variance analysis of the magnetic field and deHoffmann-Teller, as well as Minimum-Faraday-Residue analysis of plasma velocities and magnetic fields measured during the crossings. In order to improve the overall consistency between multi-and single-spacecraft results, we have also explored the use of hybrid techniques, in which timing information from the four spacecraft is combined with certain limited results from single-spacecraft methods, the remaining results being left for consistency checks. The results show good agreement between magnetopause orientations derived from appropriately chosen single-spacecraft techniques and those obtained from multi-spacecraft timing. The agreement between magnetopause speeds derived from single-and multi-spacecraft methods is quantitatively somewhat less good but it is evident that the speed can change substantially from one crossing to the next within an event. The magnetopause thickness varied Correspondence to: S. E. Haaland stein.haaland@issi.unibe.ch substantially from one crossing to the next, within an event. It ranged from 5 to 10 ion gyroradii. The density profile was sharper than the magnetic profile: most of the density change occured in the earthward half of the magnetopause.

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“…The launch of the Cluster spacecraft has enabled fourpoint observations of flux transfer events for the first time , which allows the velocity of FTEs to be determined by multi-spacecraft timing analysis (Russell et al, 1983;Harvey, 1998). Wild et al (2005) and Dunlop et al (2005) have calculated the velocities of a small number of FTEs in this way, and compared them with a model of reconnected field line motion developed by Cooling et al (2001).…”

Section: Introductionmentioning

confidence: 99%

Motion of flux transfer events: a test of the Cooling model

et al. 2007

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Abstract. The simple model of reconnected field line motion developed by Cooling et al. (2001) has been used in several recent case studies to explain the motion of flux transfer events across the magnetopause. We examine 213 FTEs observed by all four Cluster spacecraft under a variety of IMF conditions between November 2002 and June 2003, when the spacecraft tetrahedron separation was ∼5000 km. Observed velocities were calculated from multi-spacecraft timing analysis, and compared with the velocities predicted by the Cooling model in order to check the validity of the model. After excluding three categories of FTEs (events with poorly defined velocities, a significant velocity component out of the magnetopause surface, or a scale size of less than 5000 km), we were left with a sample of 118 events. 78% of these events were consistent in both direction of motion and speed with one of the two model de Hoffmann-Teller (dHT) velocities calculated from the Cooling model (to within 30 • and a factor of two in the speed). We also examined the plasma signatures of several magnetosheath FTEs; the electron signatures confirm the hemisphere of connection indicated by the model in most cases. This indicates that although the model is a simple one, it is a useful tool for identifying the source regions of FTEs.

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Multiple spacecraft observations of interplanetary shocks: Four spacecraft determination of shock normals

Cited by 231 publications

References 5 publications

A comparison of wave mode identification techniques

A comparison of wave mode identification techniques

Four-spacecraft determination of magnetopause orientation, motion and thickness: comparison with results from single-spacecraft methods

Motion of flux transfer events: a test of the Cooling model

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