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Automated force-free flux rope identification

Automated force-free flux rope identification
Automated force-free flux rope identification
We describe a method developed to automatically identify quasi force-free magnetotail flux ropes from in situ spacecraft magnetometer data. The method locates significant (greater than 1σ) deflections of the north-south component of the magnetic field coincident with enhancements in other field components. The magnetic field data around the deflections are then processed using Minimum Variance Analysis (MVA) to narrow the selection down to those that exhibit the characteristics of flux ropes. The subset of candidates that fulfills the requirements are then compared to a cylindrical, linear (constant-α) force-free model. Those that can be well approximated as force free are then accepted. The model fit also provides a measure of the physical parameters that describe the flux rope (i.e., core field and radius). This process allows for the creation of a repeatable, consistent catalog of flux ropes. Automation allows a greater volume of data to be covered, saving time and allowing the exploration of potential selection biases. The technique is applied to MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) magnetometer data in the Hermean magnetotail and successfully locates flux ropes, some of which match previously known encounters. Assumptions of the method and potential future applications are discussed.
2169-9380
780-791
Smith, A.W.
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Slavin, J.A.
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Jackman, C.M.
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Fear, R.C.
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Poh, G.-K.
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DiBraccio, G.A.
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Jasinski, J.M.
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Trenchi, L.
565a6c2f-9b87-4a3a-a453-ff7cfecbb266
Smith, A.W.
f719dbf6-612c-4ecb-9ec8-ae0ac74928eb
Slavin, J.A.
ad9f2244-00ad-4a9a-9832-b620b8afb145
Jackman, C.M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Fear, R.C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Poh, G.-K.
221896e9-467e-47cc-84c2-33dfceb96909
DiBraccio, G.A.
f2dc8928-5019-40f0-a991-1f2e615961a5
Jasinski, J.M.
b4cbe42a-e431-4a18-967b-a79ca51173b2
Trenchi, L.
565a6c2f-9b87-4a3a-a453-ff7cfecbb266

Smith, A.W., Slavin, J.A., Jackman, C.M., Fear, R.C., Poh, G.-K., DiBraccio, G.A., Jasinski, J.M. and Trenchi, L. (2017) Automated force-free flux rope identification. Journal of Geophysical Research: Space Physics, 122 (1), 780-791. (doi:10.1002/2016JA022994).

Record type: Article

Abstract

We describe a method developed to automatically identify quasi force-free magnetotail flux ropes from in situ spacecraft magnetometer data. The method locates significant (greater than 1σ) deflections of the north-south component of the magnetic field coincident with enhancements in other field components. The magnetic field data around the deflections are then processed using Minimum Variance Analysis (MVA) to narrow the selection down to those that exhibit the characteristics of flux ropes. The subset of candidates that fulfills the requirements are then compared to a cylindrical, linear (constant-α) force-free model. Those that can be well approximated as force free are then accepted. The model fit also provides a measure of the physical parameters that describe the flux rope (i.e., core field and radius). This process allows for the creation of a repeatable, consistent catalog of flux ropes. Automation allows a greater volume of data to be covered, saving time and allowing the exploration of potential selection biases. The technique is applied to MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) magnetometer data in the Hermean magnetotail and successfully locates flux ropes, some of which match previously known encounters. Assumptions of the method and potential future applications are discussed.

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Accepted/In Press date: 22 December 2016
e-pub ahead of print date: 25 January 2017
Published date: 25 January 2017
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 405645
URI: http://eprints.soton.ac.uk/id/eprint/405645
ISSN: 2169-9380
PURE UUID: fb63ed1d-18c9-4032-8a9e-d66684a47acd
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

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Date deposited: 10 Feb 2017 10:08
Last modified: 18 Feb 2021 17:23

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