Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

S Tomita; M Nose´; T Iyemori; H Toh; M Takeda; Jürgen Matzka; G Bjornsson; T Saemundsson; A Janzhura; O Troshichev; G Schwarz

doi:10.5194/angeo-29-673-2011

Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

S Tomita, M Nose´, T Iyemori, H Toh, M Takeda, Jürgen Matzka, G Bjornsson, T Saemundsson, A Janzhura, O Troshichev, G Schwarz

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Abstract

The Auroral Electrojet (AE) indices, which are composed of four indices (AU, AL, AE, and AO), are calculated from the geomagnetic field data obtained at 12 geomagnetic observatories that are located in geomagnetic latitude (GMLAT) of 61.7°-70°. The indices have been widely used to study magnetic activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT, ~06:00 MLT; and AL: ~02:00 MLT, 09:00-12:00 MLT) contributing to the index during quiet periods and one MLT range (AU: 15:00-20:00MLT, and AL: 00:00-06:00 MLT) during disturbed periods. These results are interpreted in terms of various ionospheric current systems, such as, Sqp, Sq, and DP2.

Original language	English
Journal	Annales Geophysicae
Volume	29
Issue number	4
Pages (from-to)	673-678
ISSN	0992-7689
DOIs	https://doi.org/10.5194/angeo-29-673-2011
Publication status	Published - 2010

Keywords

Storms and substorms
Magnetospheric physics
Auroral phenomena

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title = "Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices",

abstract = "The Auroral Electrojet (AE) indices, which are composed of four indices (AU, AL, AE, and AO), are calculated from the geomagnetic field data obtained at 12 geomagnetic observatories that are located in geomagnetic latitude (GMLAT) of 61.7°-70°. The indices have been widely used to study magnetic activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT, ~06:00 MLT; and AL: ~02:00 MLT, 09:00-12:00 MLT) contributing to the index during quiet periods and one MLT range (AU: 15:00-20:00MLT, and AL: 00:00-06:00 MLT) during disturbed periods. These results are interpreted in terms of various ionospheric current systems, such as, Sqp, Sq, and DP2.",

keywords = "Storms and substorms, Magnetospheric physics, Auroral phenomena",

author = "S Tomita and M Nose´ and T Iyemori and H Toh and M Takeda and J{\"u}rgen Matzka and G Bjornsson and T Saemundsson and A Janzhura and O Troshichev and G Schwarz",

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language = "English",

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TY - JOUR

T1 - Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

AU - Tomita, S

AU - Nose´, M

AU - Iyemori, T

AU - Toh, H

AU - Takeda, M

AU - Matzka, Jürgen

AU - Bjornsson, G

AU - Saemundsson, T

AU - Janzhura, A

AU - Troshichev, O

AU - Schwarz, G

PY - 2010

Y1 - 2010

N2 - The Auroral Electrojet (AE) indices, which are composed of four indices (AU, AL, AE, and AO), are calculated from the geomagnetic field data obtained at 12 geomagnetic observatories that are located in geomagnetic latitude (GMLAT) of 61.7°-70°. The indices have been widely used to study magnetic activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT, ~06:00 MLT; and AL: ~02:00 MLT, 09:00-12:00 MLT) contributing to the index during quiet periods and one MLT range (AU: 15:00-20:00MLT, and AL: 00:00-06:00 MLT) during disturbed periods. These results are interpreted in terms of various ionospheric current systems, such as, Sqp, Sq, and DP2.

AB - The Auroral Electrojet (AE) indices, which are composed of four indices (AU, AL, AE, and AO), are calculated from the geomagnetic field data obtained at 12 geomagnetic observatories that are located in geomagnetic latitude (GMLAT) of 61.7°-70°. The indices have been widely used to study magnetic activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT, ~06:00 MLT; and AL: ~02:00 MLT, 09:00-12:00 MLT) contributing to the index during quiet periods and one MLT range (AU: 15:00-20:00MLT, and AL: 00:00-06:00 MLT) during disturbed periods. These results are interpreted in terms of various ionospheric current systems, such as, Sqp, Sq, and DP2.

KW - Storms and substorms

KW - Magnetospheric physics

KW - Auroral phenomena

U2 - 10.5194/angeo-29-673-2011

DO - 10.5194/angeo-29-673-2011

M3 - Journal article

SN - 0992-7689

VL - 29

SP - 673

EP - 678

JO - Annales Geophysicae

JF - Annales Geophysicae

IS - 4

ER -

Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

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Keywords

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