Statistical study of linear magnetic hole structures near Earth

Volwerk, M.; Mautner, David; Wedlund, Cyril Simon; Goetz, Charlotte; Plaschke, Ferdinand; Karlsson, Tomas; Schmid, Daniel; Rojas‐Castillo, Diana; Roberts, Owen; Varsani, A.

doi:10.5194/angeo-39-239-2021

Cited by 22 publications

(21 citation statements)

References 46 publications

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“…This suggests that MMs, after being created upstream of their detection place, are convected down to it with the ambient plasma flow. Using the full MAVEN plasma complement and owing to the ambient plasma becoming less unstable to MMs the further away from the shock, the locus of generation of the MMs found by Simon Wedlund et al (2022c) was inferred to be in the immediate wake of the quasi-perpendicular shock, a condition that seems to predominate in the2014-2021 MAVEN dataset (Simon Wedlund et al, 2022b.https://doi.org/10.5194/egusphere-2022-634 Preprint. Discussion started: 26 July 2022 c Author(s) 2022.…”

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confidence: 91%

Statistical distribution of mirror mode-like structures in the magnetosheaths of unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft

Wedlund

Volwerk

Mazelle

et al. 2022

Preprint

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Abstract. In this series of papers, we present statistical maps of mirror mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on Extreme Ultraviolet (EUV) solar flux levels (high and low), and, specific to Mars, on Mars Year (MY) as well as atmospheric seasons (four solar longitudes Ls). We first use magnetic field-only criteria to detect these structures and present ways to mitigate ambiguities in the nature of the detected structures. In line with many previous studies at Earth, this technique has the advantage of using one instrument (a magnetometer) with good time resolution facilitating comparisons between planetary and cometary environments. Applied to the magnetometer data of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft from November 2014 to February 2020 (MY32–MY35), we detect structures closely resembling MMs lasting in total more than 170,000 s, corresponding to about 0.1 % of MAVEN's total time spent in the Martian plasma environment. We calculate MM-like occurrences normalised to the spacecraft's residence time during the course of the mission. Detection probabilities are about 1 % at most for any given controlling parameter. In general, MM-like structures appear in two main regions, one behind the shock, the other close to the induced magnetospheric boundary, as expected from theory. Detection probabilities are higher on average in low solar EUV conditions, whereas high solar EUV conditions see an increase in detections within the magnetospheric tail. We tentatively link the former tendency to two combining effects: the favouring of ion cyclotron waves the closer to perihelion due to plasma beta effects, and, possibly, the nongyrotropy of pickup ion distributions. This study is the first of two on the magnetosheaths of Mars and Venus.

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confidence: 91%

Statistical distribution of mirror mode-like structures in the magnetosheaths of unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft

Wedlund

Volwerk

Mazelle

et al. 2022

Preprint

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“…There are rich of magnetic field fluctuations and structures in the solar wind, such as Alfvén waves (Li H et al, 2016;Wu DJ et al, 2016), mirror mode structures (Volwerk et al, 2021;Wang GQ et al, 2021a), and discontinuities (Artemyev et al, 2019;Neukirch et al, 2020). We need to select the magnetic field fluctuation with a highly Alfvénic nature from the partially calibrated data.…”

Section: Selection Of the Potential Alfvénic Fluctuation Eventmentioning

confidence: 99%

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang–Pan method

Hu¹,

Wang²,

Pan³

2022

Earth and Planetary Physics

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The space-borne fluxgate magnetometer (FGM) needs regular in-flight calibration to obtain its zero offset. Recently, a new method based on the properties of Alfvén waves for the zero offset calibration was developed by Wang GQ and Pan ZH (2021a). They found that there exists an optimal offset line (OOL) in the offset cube for might also be applied to find fluctuation events for the Davis-Smith method.

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“…There are rich of magnetic field fluctuations and structures in the solar wind, such as Alfvén waves (Li et al, 2016;Wu et al, 2016), mirror mode structures (Volwerk et al, 2021;Wang et al, 2021a), and discontinuities (Artemyev et al, 2019;Neukirch et al, 2020). We need to select the magnetic field fluctuation with a highly Alfvénic nature from the partially calibrated data.…”

Section: Selection Of the Highly Alfvénic Fluctuation Eventmentioning

confidence: 99%

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang-Pan method

Wang

Pan

et al. 2021

Preprint

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Abstract. The space-borne fluxgate magnetometer (FGM) needs regular in-flight calibration to obtain its zero offset. Recently, a new method based on the properties of Alfvén waves for the zero offset calibration was developed by Wang and Pan (2021). They found that there exists an optimal offset line (OOL) in the offset cube for a pure Alfvén wave, and the zero offset can be determined by the intersection of at least two non-parallel OOLs. Since no pure Alfvén waves exist in the interplanetary magnetic field, the calculation of the zero offset relies on the selection of the highly Alfvénic fluctuation event. Here, we propose an automatic procedure to find highly Alfvénic fluctuations in the solar wind and calculate the zero offset. This procedure includes three parts: (1) selection of highly Alfvénic fluctuation events, (2) evaluation of the OOL of the selected fluctuation events, and (3) determination of the zero offset. We test our automatic procedure by applying it to the magnetic field data measured by the FGM onboard Venus Express. The tests reveal that our automatic procedure is able to achieve as good results as the Davis-Smith method. One advantage of our procedure is that the selection criteria and process for the highly Alfvénic fluctuation event are simpler. Our automatic procedure might also be applied to find fluctuation events for the Davis-Smith method after proper modification.

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Statistical study of linear magnetic hole structures near Earth

Cited by 22 publications

References 46 publications

Statistical distribution of mirror mode-like structures in the magnetosheaths of unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft

Statistical distribution of mirror mode-like structures in the magnetosheaths of unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang–Pan method

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang-Pan method

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