Cluster as a wave telescope – first results from the fluxgate magnetometer

Glaßmeier, Karl‐Heinz; Motschmann, U.; Dunlop, M. W.; Balogh, A.; Acuña, M. H.; Carr, C.; Musmann, G.; Fornaçon, K.‐H.; Schweda, K.; Vogt, Joachim; Georgescu, E.; Buchert, Stephan

doi:10.5194/angeo-19-1439-2001

Cited by 129 publications

(138 citation statements)

References 13 publications

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“…The lag time between the spacecraft and the location of the spacecraft are least-square fitted to obtain the three-dimensional velocity vector, v≈(287, 53, −18) km/s, with respect to the tetrahedron. (A more elaborate method for determining the wave propagation direction is described by Glassmeier et al (2001). Unfortunately, this method needs much longer time intervals than are available in our case.)…”

Section: The Datamentioning

confidence: 99%

Compressional waves in the Earth's neutral sheet

et al. 2004

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Abstract. Compressional waves in the Earth's current sheet, driven by the high-speed plasma flows connected to substorms, are investigated using the Cluster magnetometer and plasma instrument. During the time that Cluster had its apogee in the magnetotail (July through October 2001), we have studied 5 events in detail. We find compressional waves in the 30-60 mHz band, at a spectral power density that is dependent on when and where the event is observed. There is a difference of two orders of magnitude in power density between waves at substorm onset and waves during quiet times. Strong plasma flows are the driver of the wave power. The spacecraft location in the current sheet is also important for the spectral power density. Having four spacecraft available we can discern spatial from temporal variations. We have determined the propagation direction of the waves in the 30-60 mHz band and found that in the Cluster rest frame they propagate in the same direction as the plasma flow at an angle 30 • < φ < 40 • with respect to the plasma flow direction in the spacecraft' rest frame.

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Section: The Datamentioning

confidence: 99%

Compressional waves in the Earth's neutral sheet

et al. 2004

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“…The k-filtering technique (Pinçon and Motschmann, 1998;Glassmeier et al, 2001) enables the identification of threedimensional structures in the wave field. It assumes that the fields that exist may be described by Eq.…”

Section: The K-filtering Techniquementioning

confidence: 99%

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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“…The Cluster magnetometer team also published several aspects of four-point analysis techniques specifically related to magnetic field data since 1990 (for a comprehensive list of publications on this topic, see Balogh and Dunlop, 2000, but also Dunlop et al, 1996Dunlop et al, , 1997Woodward, 1998, 2000). First reviews of applications of these techniques using Cluster magnetic field data are presented in Dunlop et al (2001b), and Glassmeier et al (2001).…”

Section: Introduction: Scientific Objectives Of the Cluster Magnetic mentioning

confidence: 99%

The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results

Balogh

Carr

Acuña³

et al. 2001

Ann. Geophys.

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Abstract. The accurate measurement of the magnetic field along the orbits of the four Cluster spacecraft is a primary objective of the mission. The magnetic field is a key constituent of the plasma in and around the magnetosphere, and it plays an active role in all physical processes that define the structure and dynamics of magnetospheric phenomena on all scales. With the four-point measurements on Cluster, it has become possible to study the three-dimensional aspects of space plasma phenomena on scales commeasurable with the size of the spacecraft constellation, and to distinguish temporal and spatial dependences of small-scale processes. We present an overview of the instrumentation used to measure the magnetic field on the four Cluster spacecraft and an overview the performance of the operational modes used in flight. We also report on the results of the preliminary in-orbit calibration of the magnetometers; these results show that all components of the magnetic field are measured with an accuracy approaching 0.1 nT. Further data analysis is expected to bring an even more accurate determination of the calibration parameters. Several examples of the capabilities of the investigation are presented from the commissioning phase of the mission, and from the different regions visited by the spacecraft to date: the tail current sheet, the dusk side magnetopause and magnetosheath, the bow shock and the cusp. We also describe the data processing flow and the implementation of data distribution to other Cluster investigations and to the scientific community in general.

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Cluster as a wave telescope – first results from the fluxgate magnetometer

Cited by 129 publications

References 13 publications

Compressional waves in the Earth's neutral sheet

Compressional waves in the Earth's neutral sheet

A comparison of wave mode identification techniques

The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results

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