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Evaluating single spacecraft observations of planetary magnetotails with simple Monte Carlo Simulations: 2. Magnetic flux rope signature selection effects

Evaluating single spacecraft observations of planetary magnetotails with simple Monte Carlo Simulations: 2. Magnetic flux rope signature selection effects
Evaluating single spacecraft observations of planetary magnetotails with simple Monte Carlo Simulations: 2. Magnetic flux rope signature selection effects

A Monte Carlo method of investigating the effects of placing selection criteria on the magnetic signature of in situ encounters with flux ropes is presented. The technique is applied to two recent flux rope surveys of MESSENGER data within the Hermean magnetotail. It is found that the different criteria placed upon the signatures will preferentially identify slightly different subsets of the underlying population. Quantifying the selection biases first allows the distributions of flux rope parameters to be corrected, allowing a more accurate estimation of the intrinsic distributions. This is shown with regard to the distribution of flux rope radii observed. When accounting for the selection criteria, the mean radius of Hermean magnetotail quasi-force-free flux ropes is found to be 589+273 −269 km. Second, it is possible to weight the known identifications in order to determine a rate of recurrence that accounts for the presence of the structures that will not be identified. In the case of the Hermean magnetotail, the average rate of quasi-force-free flux ropes is found to 0.12 min−1 when selection effects are accounted for (up from 0.05 min−1 previously inferred from observations).

flux ropes, magnetotail, Mercury, MESSENGER, Monte Carlo, reconnection
2169-9380
10124-10138
Smith, A. W.
f719dbf6-612c-4ecb-9ec8-ae0ac74928eb
Jackman, C. M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Frohmaier, C. M.
9e031e04-b5ac-4949-80a5-92e5e13201c0
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Slavin, J. A.
40c1eb46-992c-4bf4-be56-df0dcc75759a
Coxon, J. C.
566baea5-6a30-4855-bde3-a09c115efde4
Smith, A. W.
f719dbf6-612c-4ecb-9ec8-ae0ac74928eb
Jackman, C. M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Frohmaier, C. M.
9e031e04-b5ac-4949-80a5-92e5e13201c0
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Slavin, J. A.
40c1eb46-992c-4bf4-be56-df0dcc75759a
Coxon, J. C.
566baea5-6a30-4855-bde3-a09c115efde4

Smith, A. W., Jackman, C. M., Frohmaier, C. M., Fear, R. C., Slavin, J. A. and Coxon, J. C. (2018) Evaluating single spacecraft observations of planetary magnetotails with simple Monte Carlo Simulations: 2. Magnetic flux rope signature selection effects. Journal of Geophysical Research: Space Physics, 123 (12), 10124-10138. (doi:10.1029/2018JA025959).

Record type: Article

Abstract

A Monte Carlo method of investigating the effects of placing selection criteria on the magnetic signature of in situ encounters with flux ropes is presented. The technique is applied to two recent flux rope surveys of MESSENGER data within the Hermean magnetotail. It is found that the different criteria placed upon the signatures will preferentially identify slightly different subsets of the underlying population. Quantifying the selection biases first allows the distributions of flux rope parameters to be corrected, allowing a more accurate estimation of the intrinsic distributions. This is shown with regard to the distribution of flux rope radii observed. When accounting for the selection criteria, the mean radius of Hermean magnetotail quasi-force-free flux ropes is found to be 589+273 −269 km. Second, it is possible to weight the known identifications in order to determine a rate of recurrence that accounts for the presence of the structures that will not be identified. In the case of the Hermean magnetotail, the average rate of quasi-force-free flux ropes is found to 0.12 min−1 when selection effects are accounted for (up from 0.05 min−1 previously inferred from observations).

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Smith_et_al-2018-Journal_of_Geophysical_Research__Space_Physics - Version of Record
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Accepted/In Press date: 20 November 2018
e-pub ahead of print date: 10 December 2018
Published date: December 2018
Keywords: flux ropes, magnetotail, Mercury, MESSENGER, Monte Carlo, reconnection

Identifiers

Local EPrints ID: 427615
URI: https://eprints.soton.ac.uk/id/eprint/427615
ISSN: 2169-9380
PURE UUID: a297b54e-3f93-4927-b222-cbd2858fc8f8
ORCID for A. W. Smith: ORCID iD orcid.org/0000-0001-7321-4331
ORCID for C. M. Jackman: ORCID iD orcid.org/0000-0003-0635-7361
ORCID for R. C. Fear: ORCID iD orcid.org/0000-0003-0589-7147
ORCID for J. C. Coxon: ORCID iD orcid.org/0000-0002-0166-6854

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Date deposited: 24 Jan 2019 17:30
Last modified: 13 Dec 2019 01:31

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