### Abstract

In order to correctly describe the dynamical behavior of the magnetosphere-ionosphere (MI) coupling system and the scale-dependent auroral process, we develop a synthesis formulation that combines the process of (1) the inverse Walen separation of MHD disturbance into parallel- and antiparallel-propagating shear Alfvén wave to the ambient magnetic field, (2) the shear Alfvén wave reflection process including (3) the scale-dependent electrostatic coupling process through the linearized Knight relation, (4) two-layer ionosphere model, and (5) dynamic conductance variations. A novel procedure that applies the inverse Walen relation to the incompressional MHD disturbances at the inner boundary of the MHD region enables to extract the component of the shear Alfvén wave incident to the ionosphere. The extracted incident electric field supplies an electromotive force for the generation of the MI coupling system, and the reflected electric field is generated such that it totally satisfies the synthesis MI-coupling equation. A three-dimensional ionospheric current system is represented by a two-layer model in which the Pedersen and the Hall current are confined in the separated layers, which are connected by field-aligned currents driven by the linear current-voltage relation between two layers. Hence, our scheme possibly reproduces two types of the scale-dependent MI-decoupling process of the perpendicular potential structure: due to the parallel potential drop at the auroral acceleration region and the other due to the parallel potential differences inside the ionosphere. Our newly formulation may be well suited for description of scale-dependent auroral process and mesoscale ionospheric electrodynamics interlocked with the dynamical development of magnetospheric processes.

Original language | English |
---|---|

Article number | A08218 |

Journal | Journal of Geophysical Research: Space Physics |

Volume | 116 |

Issue number | 8 |

DOIs | |

Publication status | Published - Jan 1 2011 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Geophysics
- Forestry
- Oceanography
- Aquatic Science
- Ecology
- Water Science and Technology
- Soil Science
- Geochemistry and Petrology
- Earth-Surface Processes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
- Palaeontology

### Cite this

*Journal of Geophysical Research: Space Physics*,

*116*(8), [A08218]. https://doi.org/10.1029/2011JA016460

**A self-consistent synthesis description of magnetosphere-ionosphere coupling and scale-dependent auroral process using shear Alfvén wave.** / Yoshikawa, A.; Amm, O.; Vanhamäki, H.; Fujii, R.

Research output: Contribution to journal › Article

*Journal of Geophysical Research: Space Physics*, vol. 116, no. 8, A08218. https://doi.org/10.1029/2011JA016460

}

TY - JOUR

T1 - A self-consistent synthesis description of magnetosphere-ionosphere coupling and scale-dependent auroral process using shear Alfvén wave

AU - Yoshikawa, A.

AU - Amm, O.

AU - Vanhamäki, H.

AU - Fujii, R.

PY - 2011/1/1

Y1 - 2011/1/1

N2 - In order to correctly describe the dynamical behavior of the magnetosphere-ionosphere (MI) coupling system and the scale-dependent auroral process, we develop a synthesis formulation that combines the process of (1) the inverse Walen separation of MHD disturbance into parallel- and antiparallel-propagating shear Alfvén wave to the ambient magnetic field, (2) the shear Alfvén wave reflection process including (3) the scale-dependent electrostatic coupling process through the linearized Knight relation, (4) two-layer ionosphere model, and (5) dynamic conductance variations. A novel procedure that applies the inverse Walen relation to the incompressional MHD disturbances at the inner boundary of the MHD region enables to extract the component of the shear Alfvén wave incident to the ionosphere. The extracted incident electric field supplies an electromotive force for the generation of the MI coupling system, and the reflected electric field is generated such that it totally satisfies the synthesis MI-coupling equation. A three-dimensional ionospheric current system is represented by a two-layer model in which the Pedersen and the Hall current are confined in the separated layers, which are connected by field-aligned currents driven by the linear current-voltage relation between two layers. Hence, our scheme possibly reproduces two types of the scale-dependent MI-decoupling process of the perpendicular potential structure: due to the parallel potential drop at the auroral acceleration region and the other due to the parallel potential differences inside the ionosphere. Our newly formulation may be well suited for description of scale-dependent auroral process and mesoscale ionospheric electrodynamics interlocked with the dynamical development of magnetospheric processes.

AB - In order to correctly describe the dynamical behavior of the magnetosphere-ionosphere (MI) coupling system and the scale-dependent auroral process, we develop a synthesis formulation that combines the process of (1) the inverse Walen separation of MHD disturbance into parallel- and antiparallel-propagating shear Alfvén wave to the ambient magnetic field, (2) the shear Alfvén wave reflection process including (3) the scale-dependent electrostatic coupling process through the linearized Knight relation, (4) two-layer ionosphere model, and (5) dynamic conductance variations. A novel procedure that applies the inverse Walen relation to the incompressional MHD disturbances at the inner boundary of the MHD region enables to extract the component of the shear Alfvén wave incident to the ionosphere. The extracted incident electric field supplies an electromotive force for the generation of the MI coupling system, and the reflected electric field is generated such that it totally satisfies the synthesis MI-coupling equation. A three-dimensional ionospheric current system is represented by a two-layer model in which the Pedersen and the Hall current are confined in the separated layers, which are connected by field-aligned currents driven by the linear current-voltage relation between two layers. Hence, our scheme possibly reproduces two types of the scale-dependent MI-decoupling process of the perpendicular potential structure: due to the parallel potential drop at the auroral acceleration region and the other due to the parallel potential differences inside the ionosphere. Our newly formulation may be well suited for description of scale-dependent auroral process and mesoscale ionospheric electrodynamics interlocked with the dynamical development of magnetospheric processes.

UR - http://www.scopus.com/inward/record.url?scp=84860395985&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84860395985&partnerID=8YFLogxK

U2 - 10.1029/2011JA016460

DO - 10.1029/2011JA016460

M3 - Article

AN - SCOPUS:84860395985

VL - 116

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 0148-0227

IS - 8

M1 - A08218

ER -