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Spatial variation in the responses of the surface external and induced magnetic field to the solar wind

Spatial variation in the responses of the surface external and induced magnetic field to the solar wind
Spatial variation in the responses of the surface external and induced magnetic field to the solar wind
We analyze the spatial variation in the response of the surface geomagnetic field (or the equivalent ionospheric current) to variations in the solar wind. Specifically, we regress a reanalysis of surface external and induced magnetic field (SEIMF) variations onto measurements of the solar wind. The regression is performed in monthly sets, independently for 559 regularly spaced locations covering the entire northern polar region above 50° magnetic latitude. At each location, we find the lag applied to the solar wind data that maximizes the correlation with the SEIMF. The resulting spatial maps of these independent lags and regression coefficients provide a model of the localized SEIMF response to variations in the solar wind, which we call “Spatial Information from Distributed Exogenous Regression.” We find that the lag and regression coefficients vary systematically with ionospheric region, season, and solar wind driver. In the polar cap region the SEIMF is best described by the By component of the interplanetary magnetic field (50–75% of total variance explained) at a lag ~20–25 min. Conversely, in the auroral zone the SEIMF is best described by the solar wind ϵ function (60–80% of total variance explained), with a lag that varies with season and magnetic local time (MLT), from ~15–20 min for dayside and afternoon MLT (except in Oct–Dec) to typically 30–40 min for nightside and morning MLT and even longer (60–65 min) around midnight MLT.
2169-9380
1-17
Shore, R.M.
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Freeman, M.P.
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Coxon, J.C.
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Thomas, E.G.
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Gjerloev, J.W.
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Olsen, N.
a11f4782-d2e8-4fea-a3f7-51cc63a095e5
Shore, R.M.
2dedf638-01a2-432a-9e77-f17540124166
Freeman, M.P.
dc974e00-a73d-4d41-a2a8-3c5aebd7a5b5
Coxon, J.C.
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Thomas, E.G.
a7a4d08a-c815-42f1-84f0-a74cfe2a6b6b
Gjerloev, J.W.
bbd250d5-63b4-4123-93fe-fd630ede94dd
Olsen, N.
a11f4782-d2e8-4fea-a3f7-51cc63a095e5

Shore, R.M., Freeman, M.P., Coxon, J.C., Thomas, E.G., Gjerloev, J.W. and Olsen, N. (2019) Spatial variation in the responses of the surface external and induced magnetic field to the solar wind. Journal of Geophysical Research: Space Physics, 1-17. (doi:10.1029/2019JA026543).

Record type: Article

Abstract

We analyze the spatial variation in the response of the surface geomagnetic field (or the equivalent ionospheric current) to variations in the solar wind. Specifically, we regress a reanalysis of surface external and induced magnetic field (SEIMF) variations onto measurements of the solar wind. The regression is performed in monthly sets, independently for 559 regularly spaced locations covering the entire northern polar region above 50° magnetic latitude. At each location, we find the lag applied to the solar wind data that maximizes the correlation with the SEIMF. The resulting spatial maps of these independent lags and regression coefficients provide a model of the localized SEIMF response to variations in the solar wind, which we call “Spatial Information from Distributed Exogenous Regression.” We find that the lag and regression coefficients vary systematically with ionospheric region, season, and solar wind driver. In the polar cap region the SEIMF is best described by the By component of the interplanetary magnetic field (50–75% of total variance explained) at a lag ~20–25 min. Conversely, in the auroral zone the SEIMF is best described by the solar wind ϵ function (60–80% of total variance explained), with a lag that varies with season and magnetic local time (MLT), from ~15–20 min for dayside and afternoon MLT (except in Oct–Dec) to typically 30–40 min for nightside and morning MLT and even longer (60–65 min) around midnight MLT.

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Shore et al 2019 Journal of Geophysical Research Space Physics - Version of Record
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More information

Submitted date: 28 January 2019
Accepted/In Press date: 10 June 2019
e-pub ahead of print date: 5 July 2019

Identifiers

Local EPrints ID: 433156
URI: https://eprints.soton.ac.uk/id/eprint/433156
ISSN: 2169-9380
PURE UUID: 0c6d4166-d1e1-4144-8a1a-f4cb0b60ad77
ORCID for J.C. Coxon: ORCID iD orcid.org/0000-0002-0166-6854

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Date deposited: 09 Aug 2019 16:30
Last modified: 10 Dec 2019 01:33

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Contributors

Author: R.M. Shore
Author: M.P. Freeman
Author: J.C. Coxon ORCID iD
Author: E.G. Thomas
Author: J.W. Gjerloev
Author: N. Olsen

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