Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements

K. M. Laundal*, C. C. Finlay, N. Olsen, J. P. Reistad

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

218 Downloads (Pure)

Abstract

We present a new climatological model of the ionospheric current system, determined from magnetic measurements taken by the CHAMP and Swarm satellites. The model describes the horizontal currents in the ionosphere, below the satellites, and the field‐aligned (Birkeland) currents that connect the ionosphere with the magnetosphere. The model provides ionospheric current values at any location as continuous functions of solar wind speed, interplanetary magnetic field (IMF), dipole tilt angle, and the F10.7 index of solar flux. Geometric distortions due to variations in the Earth's main magnetic field are taken into account, thus allowing for precise comparisons between the two hemispheres. The model is the first of its kind to describe the full 3D electric currents, and not only the field‐aligned or the equivalent horizontal current. We use this capability to demonstrate a key difference between seasons: During winter, the total horizontal current is almost entirely confined to the auroral oval, for all IMF orientations, where it connects upward and downward Birkeland currents. During more sunlit conditions, the horizontal current extends beyond the auroral oval, and is a sum of currents connecting Birkeland currents and currents that circulate in the ionosphere. The westward electrojet is the only large‐scale current structure that is persistent across seasons. Comparison with average convection maps suggests that it is comprised largely of Hall currents, which connect to Birkeland currents in the winter but not in summer.
Original languageEnglish
JournalJournal of Geophysical Research: Space Physics
Volume123
Issue number5
Pages (from-to)4402-4429
ISSN2169-9380
DOIs
Publication statusPublished - 2018

Bibliographical note

©2018. The Authors.
This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

Cite this

@article{6556bef104b742c8b20eb15b0e141159,
title = "Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements",
abstract = "We present a new climatological model of the ionospheric current system, determined from magnetic measurements taken by the CHAMP and Swarm satellites. The model describes the horizontal currents in the ionosphere, below the satellites, and the field‐aligned (Birkeland) currents that connect the ionosphere with the magnetosphere. The model provides ionospheric current values at any location as continuous functions of solar wind speed, interplanetary magnetic field (IMF), dipole tilt angle, and the F10.7 index of solar flux. Geometric distortions due to variations in the Earth's main magnetic field are taken into account, thus allowing for precise comparisons between the two hemispheres. The model is the first of its kind to describe the full 3D electric currents, and not only the field‐aligned or the equivalent horizontal current. We use this capability to demonstrate a key difference between seasons: During winter, the total horizontal current is almost entirely confined to the auroral oval, for all IMF orientations, where it connects upward and downward Birkeland currents. During more sunlit conditions, the horizontal current extends beyond the auroral oval, and is a sum of currents connecting Birkeland currents and currents that circulate in the ionosphere. The westward electrojet is the only large‐scale current structure that is persistent across seasons. Comparison with average convection maps suggests that it is comprised largely of Hall currents, which connect to Birkeland currents in the winter but not in summer.",
author = "Laundal, {K. M.} and Finlay, {C. C.} and N. Olsen and Reistad, {J. P.}",
note = "{\circledC}2018. The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.",
year = "2018",
doi = "10.1029/2018JA025387",
language = "English",
volume = "123",
pages = "4402--4429",
journal = "Journal of Geophysical Research",
issn = "0148-0227",
publisher = "American Geophysical Union",
number = "5",

}

Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements. / Laundal, K. M.; Finlay, C. C.; Olsen, N.; Reistad, J. P.

In: Journal of Geophysical Research: Space Physics, Vol. 123, No. 5, 2018, p. 4402-4429.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements

AU - Laundal, K. M.

AU - Finlay, C. C.

AU - Olsen, N.

AU - Reistad, J. P.

N1 - ©2018. The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

PY - 2018

Y1 - 2018

N2 - We present a new climatological model of the ionospheric current system, determined from magnetic measurements taken by the CHAMP and Swarm satellites. The model describes the horizontal currents in the ionosphere, below the satellites, and the field‐aligned (Birkeland) currents that connect the ionosphere with the magnetosphere. The model provides ionospheric current values at any location as continuous functions of solar wind speed, interplanetary magnetic field (IMF), dipole tilt angle, and the F10.7 index of solar flux. Geometric distortions due to variations in the Earth's main magnetic field are taken into account, thus allowing for precise comparisons between the two hemispheres. The model is the first of its kind to describe the full 3D electric currents, and not only the field‐aligned or the equivalent horizontal current. We use this capability to demonstrate a key difference between seasons: During winter, the total horizontal current is almost entirely confined to the auroral oval, for all IMF orientations, where it connects upward and downward Birkeland currents. During more sunlit conditions, the horizontal current extends beyond the auroral oval, and is a sum of currents connecting Birkeland currents and currents that circulate in the ionosphere. The westward electrojet is the only large‐scale current structure that is persistent across seasons. Comparison with average convection maps suggests that it is comprised largely of Hall currents, which connect to Birkeland currents in the winter but not in summer.

AB - We present a new climatological model of the ionospheric current system, determined from magnetic measurements taken by the CHAMP and Swarm satellites. The model describes the horizontal currents in the ionosphere, below the satellites, and the field‐aligned (Birkeland) currents that connect the ionosphere with the magnetosphere. The model provides ionospheric current values at any location as continuous functions of solar wind speed, interplanetary magnetic field (IMF), dipole tilt angle, and the F10.7 index of solar flux. Geometric distortions due to variations in the Earth's main magnetic field are taken into account, thus allowing for precise comparisons between the two hemispheres. The model is the first of its kind to describe the full 3D electric currents, and not only the field‐aligned or the equivalent horizontal current. We use this capability to demonstrate a key difference between seasons: During winter, the total horizontal current is almost entirely confined to the auroral oval, for all IMF orientations, where it connects upward and downward Birkeland currents. During more sunlit conditions, the horizontal current extends beyond the auroral oval, and is a sum of currents connecting Birkeland currents and currents that circulate in the ionosphere. The westward electrojet is the only large‐scale current structure that is persistent across seasons. Comparison with average convection maps suggests that it is comprised largely of Hall currents, which connect to Birkeland currents in the winter but not in summer.

U2 - 10.1029/2018JA025387

DO - 10.1029/2018JA025387

M3 - Journal article

VL - 123

SP - 4402

EP - 4429

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 0148-0227

IS - 5

ER -