On the origin of reverse polarity TCRs

Moldwin, M. B.; Collier, M. R.; Slavin, J. A.; Szabó, Á.

doi:10.1029/2000gl012485

Cited by 8 publications

(10 citation statements)

References 15 publications

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“…The mean compression of these tailward propagating TCRs was B/B=7.6% with a duration of 158 s. The size of these plasmoids was estimated by the TCR amplitude and duration to be approximately 35 R E in x-and 15 R E in y-and z-direction. IMP 8 observations in the mid-tail gave first evidence of the existence of earthward propagating TCRs (Moldwin and Hughes, 1994;Moldwin et al, 2001), which was supported by Cluster observations in the near tail at X>−20 R E . These near tail TCRs (Slavin et al, 2003c;Borälv et al, 2005;Sergeev et al, 2005;Owen et al, 2005) strongly resemble those in the distant tail.…”

Section: Introductionsupporting

confidence: 54%

Estimating the magnetic energy inside traveling compression regions

et al. 2009

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Abstract. We investigate a series of six TCRs (traveling compression regions), appearing in the course of a small substorm on 19 September 2001. Except for two of these TCRs, all Cluster spacecraft were located in the lobe and detected the typical signatures of TCRs, i.e., compressions in |B| and bipolar B z variations. We use these perturbations in B z for calculations on the magnetic energy inside the TCR and compare the amount of magnetic field energy with the kinetic energy inside the underlying plasma bulge. According to results obtained from theory, the amount of magnetic energy inside TCRs is about two times higher than the kinetic plasma energy inside the accompanied plasma bulge. We verify this theoretical result by first investigations of the magnetic field energy inside TCRs. The calculations lead to a magnetic energy in the order of 10 10 Joule per R E for each of the TCRs.

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Section: Introductionsupporting

confidence: 54%

Estimating the magnetic energy inside traveling compression regions

et al. 2009

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“…Such SN TCRs had been noted earlier [ Slavin et al , 1993], but they had been attributed to external compression of the tail lobes by short duration enhancements of solar wind pressure. In fact, Moldwin et al [2001] examined 21 SN TCRs and found that 17 were associated with short duration upstream solar wind pressure increases. However, they suggested that the remaining 4 events might be due to the Earthward moving “plasmoids”.…”

Section: Discussionmentioning

confidence: 99%

Geotail observations of magnetic flux ropes in the plasma sheet

et al. 2003

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[1] Examination of Geotail measurements in the near-tail (X > À30 R E ) has revealed the presence of small flux ropes in the plasma sheet. A total of 73 flux rope events were identified in the Geotail magnetic field measurements between November 1998 and April 1999. This corresponds to an estimated occurrence frequency of $1 flux rope per 5 hours of central plasma sheet observing time. All of the flux ropes were embedded within high-speed plasma sheet flows with 35 directed Earthward, hV x i = 431 km/s, and 38 moving tailward, hV x i = À451 km/s. We refer to these two populations as ''BBF-type'' and ''plasmoid-type'' flux ropes. The flux ropes were usually several tens of seconds in duration, and the two types were readily distinguished by the sense of their quasisinusoidal ÁB z perturbations, i.e., Ç for the ''BBF'' events and ± for the ''plasmoid'' events. Most typically, a flux rope was observed to closely follow the onset of a high-speed flow within $1-2 min. Application of the Lepping-Burlaga constant-a flux rope model (i.e., J = aB) to these events showed that approximately 60% of each class could be acceptably described as cylindrical, force-free flux ropes. The modeling results yielded mean flux rope diameters and core field intensities of 1.4 R E and 20 nT and 4.4 R E and 14 nT for the BBF and plasmoid-type events, respectively. The inclinations of the flux ropes were small relative to the GSM X-Y plane, but a wide range of azimuthal orientations were determined within that plane. The frequent presence of these flux ropes in the plasma sheet is interpreted as strong evidence for multiple reconnection X-lines (MRX) in the near-tail. Hence, our results suggest that reconnection in the near-tail may closely resemble that at the dayside magnetopause where MRX reconnection has been hypothesized to be responsible for the generation of flux transfer events.

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“…The lobe FTE‐type TCRs consist of several‐seconds‐long compressive perturbations with the ± B 1 normal field variation signaling their tailward motion [ Russell and Elphic , 1978; Russell and Walker , 1985, Wang et al , 2005]. FTE‐type flux ropes (Figure 6c) observed several minutes later are identified by the ± B 1 perturbation indicating tailward motion and their associated unipolar core field [ Moldwin et al , 2001; Liu et al , 2008]. When minimum variance analysis is performed on individual flux ropes, the unipolar core field increase appears in the B 2 direction as expected [ Russell and Elphic , 1978].…”

Section: Fte Shower Of 11 April 2011mentioning

confidence: 99%

MESSENGER observations of a flux‐transfer‐event shower at Mercury

et al. 2012

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[1] Analysis of MESSENGER magnetic field observations taken in the southern lobe of Mercury's magnetotail and the adjacent magnetosheath on 11 April 2011 indicates that a total of 163 flux transfer events (FTEs) occurred within a 25 min interval. Each FTE had a duration of $2-3 s and was separated in time from the next by $8-10 s. A range of values have been reported at Earth, with mean values near $1-2 min and $8 min, respectively. We term these intervals of quasiperiodic flux transfer events "FTE showers." The northward and sunward orientation of the interplanetary magnetic field during this shower strongly suggests that the FTEs observed during this event formed just tailward of Mercury's southern magnetic cusp. The point of origin for the shower was confirmed with the Cooling model of FTE motion. Modeling of the individual FTE-type flux ropes in the magnetosheath indicates that these flux ropes had elliptical cross sections, a mean semimajor axis of 0.15 R M (where R M is Mercury's radius, or 2440 km), and a mean axial magnetic flux of 1.25 MWb. The lobe magnetic field was relatively constant until the onset of the FTE shower, but thereafter the field magnitude decreased steadily until the spacecraft crossed the magnetopause. This decrease in magnetic field intensity is frequently observed during FTE showers. Such a decrease may be due to the diamagnetism of the new magnetosheath plasma being injected into the tail by the FTEs.

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On the origin of reverse polarity TCRs

Cited by 8 publications

References 15 publications

Estimating the magnetic energy inside traveling compression regions

Estimating the magnetic energy inside traveling compression regions

Geotail observations of magnetic flux ropes in the plasma sheet

MESSENGER observations of a flux‐transfer‐event shower at Mercury

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