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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 1?) 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-?) 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.
0148-0227
1-12
Smith, Andrew
f719dbf6-612c-4ecb-9ec8-ae0ac74928eb
Slavin, James
ad9f2244-00ad-4a9a-9832-b620b8afb145
Jackman, Caitriona
9bc3456c-b254-48f1-ade0-912c5b8b4529
Fear, Robert
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Poh, Gang-Kai
221896e9-467e-47cc-84c2-33dfceb96909
DiBraccio, Gina
f2dc8928-5019-40f0-a991-1f2e615961a5
Jasinski, Jamie
b4cbe42a-e431-4a18-967b-a79ca51173b2
Trenchi, Lorenzo
565a6c2f-9b87-4a3a-a453-ff7cfecbb266
Smith, Andrew
f719dbf6-612c-4ecb-9ec8-ae0ac74928eb
Slavin, James
ad9f2244-00ad-4a9a-9832-b620b8afb145
Jackman, Caitriona
9bc3456c-b254-48f1-ade0-912c5b8b4529
Fear, Robert
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Poh, Gang-Kai
221896e9-467e-47cc-84c2-33dfceb96909
DiBraccio, Gina
f2dc8928-5019-40f0-a991-1f2e615961a5
Jasinski, Jamie
b4cbe42a-e431-4a18-967b-a79ca51173b2
Trenchi, Lorenzo
565a6c2f-9b87-4a3a-a453-ff7cfecbb266

Smith, Andrew, Slavin, James, Jackman, Caitriona, Fear, Robert, Poh, Gang-Kai, DiBraccio, Gina, Jasinski, Jamie and Trenchi, Lorenzo (2017) Automated force-free flux rope identification Journal of Geophysical Research, pp. 1-12.

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 1?) 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-?) 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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More information

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

Identifiers

Local EPrints ID: 405645
URI: http://eprints.soton.ac.uk/id/eprint/405645
ISSN: 0148-0227
PURE UUID: fb63ed1d-18c9-4032-8a9e-d66684a47acd
ORCID for Andrew Smith: ORCID iD orcid.org/0000-0001-7321-4331
ORCID for Robert Fear: ORCID iD orcid.org/0000-0003-0589-7147

Catalogue record

Date deposited: 10 Feb 2017 10:08
Last modified: 30 Sep 2017 19:22

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Contributors

Author: Andrew Smith ORCID iD
Author: James Slavin
Author: Caitriona Jackman
Author: Robert Fear ORCID iD
Author: Gang-Kai Poh
Author: Gina DiBraccio
Author: Jamie Jasinski
Author: Lorenzo Trenchi

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