On determining the nature and orientation of magnetic directional discontinuities: Problems with the minimum variance method

Hausman, B. A.; Michel, F. C.; Espley, J. R.; Cloutier, P. A.

doi:10.1029/2004ja010670

Cited by 15 publications

(20 citation statements)

References 10 publications

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“…However, even at large distances from Mars (10–15 planetary radii), such wave activity could also be seen. As shown by Hausman et al [2004], this wave activity could be detected using running averages of ρ and the wave activity can be seen in the raw magnetometer data. Many TDs are evident in the data and often several can be seen in a single 5 min run so that the statistic for occurrence rates of TDs in the solar wind may be time‐resolution biased.…”

Section: Mars Global Surveyor Datamentioning

confidence: 92%

“…As discussed elsewhere [ Hausman et al , 2004], a useful tool is the determination of the running values of ρ defined by where k is the sequential (but arbitrary) magnetic record number in a data stream. The expected values of ρ are zero under a number of interesting conditions such as times of slowly varying magnetic field and in the presence of tangential discontinuities (TD).…”

Section: Introductionmentioning

confidence: 99%

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Measuring noise in magnetometers: An example using the Mars Global Surveyor magnetometers

et al. 2006

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[1] A recently developed data analysis tool allows direct measurement of the total root-mean-square noise in magnetometer data. Since the total is a combination of intrinsic instrument noise and solar wind magnetic field fluctuations, we can put upper limits on the instrument noise during periods of relatively quiet solar wind fields. The technique involves taking vector and scalar products of successive magnetic measurements; the resulting scalar quantity is insensitive to slow field variations as well as sudden ones (i.e., tangential discontinuities) and provides a measure of total noise. We illustrate this analysis by determining the noise levels for the Mars Global Surveyor magnetometer. Far from Mars and any obvious waves, we find that the magnetic field measurements noise level is ±0.05 nT. This is consistent with the ground-based instrument's measured noise level of ±0.01 nT expected under ideal conditions.

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Section: Mars Global Surveyor Datamentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Measuring noise in magnetometers: An example using the Mars Global Surveyor magnetometers

et al. 2006

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“…The first occurs near what Burch et al () identify as an exhaust jet, while the other lies within the magnetopause, with concomitant surges in E || (Figure , panel 4, shows E || for MMS1). The quantity ρ , shown for MMS1 in Figure (panel 5), is the rotational discontinuity finder as proposed by Hausman et al () that uses the magnetic field vectors from measurements before, during, and after a discontinuity crossing, ρ = ( B b × B d ) ⋅ B a , where the subscripts denote “before,” “during,” and “after,” respectively. The power of the finder ρ is that it is impervious to tangential discontinuities, picking out only rotational boundaries, which means that there is a magnetic field component normal to the boundary.…”

Section: Mms Observationsmentioning

confidence: 99%

Violation of Field Line Conservation and Associated Spatial Scales in Particle‐in‐Cell Simulations and MMS Data

et al. 2018

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For the first time, space flight technology exists to detect, in situ, violation of magnetic field line conservation. The violation of magnetic line conservation on scales smaller than the system size is a necessary and sufficient condition for finite magnetic field reconnection. We demonstrate that violation of line conservation produces a detectable, structured signature both in particle‐in‐cell simulations of reconnection and in data from the Magnetospheric Multi‐Scale mission. In particle‐in‐cell simulations of asymmetric reconnection, the quantity—which we call M—that identifies this violation achieves significant values in electron skin depth‐scale layers that extend away from the separator, with higher values emerging on the low‐density, high‐magnetic‐field side of the current sheet. At the separator, M owes largely to perpendicular gradients in the parallel electric field, while it attains its highest values away from the separator in dispersed, layered structures associated with gradients in the perpendicular nonideal electric field and electron transport. Sub‐ion scale bipolar forms of the quantity also appear further from the separator. In two MMS burst data intervals detecting the electron diffusion region, we find that M exceeds measurement uncertainties both at the separator and near the separatrices. One interval has highly sheared reconnecting fields and the other a stronger guide field. For one event, we determine the location and scale of M and the inner electron diffusion region relative to electron outflows and the magnetic separatrices. The measure can therefore serve as a potent diagnostic for magnetic reconnection in space measurements.

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“…Several authors (Behannon et al, 1981;Sonnerup and Scheible, 1998;Khrabrov and Sonnerup, 1998;Hausman et al, 2004) have pointed out problems when MVA is applied to magnetic discontinuities. One of these problems is related to the statistical nature of MVA.…”

Section: Step 3: Determining the Hcs Local Orientationmentioning

confidence: 98%

Interaction between magnetic clouds and the heliospheric current sheet at 1AU as it is observed by one single observation point

Blanco¹,

Hidalgo²,

Rodrı́guez-Pacheco³

et al. 2011

Journal of Atmospheric and Solar-Terrestrial Physics

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On determining the nature and orientation of magnetic directional discontinuities: Problems with the minimum variance method

Cited by 15 publications

References 10 publications

Measuring noise in magnetometers: An example using the Mars Global Surveyor magnetometers

Measuring noise in magnetometers: An example using the Mars Global Surveyor magnetometers

Violation of Field Line Conservation and Associated Spatial Scales in Particle‐in‐Cell Simulations and MMS Data

Interaction between magnetic clouds and the heliospheric current sheet at 1AU as it is observed by one single observation point

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