Relation between the ring current and the tail current during magnetic storms
We study the dynamics of the magnetospheric large-scale current systems during storms by using three different magnetospheric magnetic field models: the paraboloid, event-oriented, and Tsyganenko T01 models. We have modelled two storm events, one moderate storm on 25-26 June 1998, when <i>...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/523/2005/angeo-23-523-2005.pdf |
| Summary: | We study the dynamics of the magnetospheric large-scale current
systems during storms by using three different magnetospheric
magnetic field models: the paraboloid, event-oriented, and
Tsyganenko T01 models. We have modelled two storm events, one
moderate storm on 25-26 June 1998, when <i>D<sub>st</sub></i> reached -120nT
and one intense storm on 21-23 October 1999, when <i>D<sub>st</sub></i> dropped
to -250nT. We compare the observed magnetic field from GOES 8,
GOES 9, and GOES 10, Polar and Geotail satellites with the
magnetic field given by the three models to estimate their
reliability. All models demonstrated quite good agreement with
observations. Since it is difficult to measure exactly the
relative contributions from different current systems to the
<i>D<sub>st</sub></i> index, we compute the contributions from ring, tail
and magnetopause currents given by the three magnetic field
models. We discuss the dependence of the obtained contributions
to the <i>D<sub>st</sub></i> index in relation to the methods used in
constructing the models. All models show a significant tail
current contribution to the <i>D<sub>st</sub></i> index, comparable to the ring
current contribution during moderate storms. The ring current
becomes the major <i>D<sub>st</sub></i> source during intense storms. |
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| ISSN: | 0992-7689 1432-0576 |