Long-term evolution of magnetospheric current systems during storms
We present a method to model the storm-time magnetospheric magnetic field using representations of the magnetic field arising from the various magnetospheric current systems. We incorporate the effects of magnetotail changes during substorms by introducing an additional localized thin current sh...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2004-04-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/22/1317/2004/angeo-22-1317-2004.pdf |
| _version_ | 1828779836746760192 |
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| author | N. Yu. Ganushkina T. I. Pulkkinen M. V. Kubyshkina H. J. Singer C. T. Russell |
| author_facet | N. Yu. Ganushkina T. I. Pulkkinen M. V. Kubyshkina H. J. Singer C. T. Russell |
| author_sort | N. Yu. Ganushkina |
| collection | DOAJ |
| description | We present a method to model the storm-time magnetospheric
magnetic field using representations of the magnetic field arising
from the various magnetospheric current systems. We incorporate
the effects of magnetotail changes during substorms by introducing
an additional localized thin current sheet into the Tsyganenko T89
model. To represent the storm-time ring current the T89 ring
current is replaced by a bean-shaped current system, which has a
cross section that is close to the observed distribution of
trapped particles in the inner magnetosphere and has an eastward
flowing inner and westward flowing outer components. In addition
to the symmetric ring current, an asymmetric partial ring current
is taken into account with closing Region 2 sense field-aligned
currents. Magnetopause currents are varied in accordance with
solar wind dynamic pressure variations. Three moderate geomagnetic
storms when <i>D<sub>st</sub></i> reached about –150 nT and one big storm
with <i>D<sub>st</sub></i> about –250 nT are modelled. The model free
parameters are specified for each time step separately using
observations from GOES 8 and 9, Polar, Interball and Geotail
satellites and <i>D<sub>st</sub></i> measurements. The model gives a high
time-resolution field representation of the large-scale magnetic
field, and a very good reproduction of the <i>D<sub>st</sub></i> index. It is
shown that the ring current is most important during intense
storms, whereas the near-Earth tail currents contribute more to
the <i>D<sub>st</sub></i> index than the ring current during moderate storms.<br><br>
<b>Key words.</b> Magnetospheric physics (Current systems;
Magnetospheric configuration and dynamics; Storms and
substorms) |
| first_indexed | 2024-12-11T17:08:35Z |
| format | Article |
| id | doaj.art-e240995b361b468aa7057a141a50720f |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-11T17:08:35Z |
| publishDate | 2004-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-e240995b361b468aa7057a141a50720f2022-12-22T00:57:36ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762004-04-01221317133410.5194/angeo-22-1317-2004Long-term evolution of magnetospheric current systems during stormsN. Yu. Ganushkina0T. I. Pulkkinen1M. V. Kubyshkina2H. J. Singer3C. T. Russell4Finnish Meteorological Institute, Geophysical Research Division,P.O. Box 503, FIN-00101 Helsinki, FinlandFinnish Meteorological Institute, Geophysical Research Division,P.O. Box 503, FIN-00101 Helsinki, FinlandInstitute of Physics, University of St.-Petersburg, St.-Petersburg,198904, RussiaNOAA Space Environment Center, Boulder, CO 80303-3328, USAInstitute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USAWe present a method to model the storm-time magnetospheric magnetic field using representations of the magnetic field arising from the various magnetospheric current systems. We incorporate the effects of magnetotail changes during substorms by introducing an additional localized thin current sheet into the Tsyganenko T89 model. To represent the storm-time ring current the T89 ring current is replaced by a bean-shaped current system, which has a cross section that is close to the observed distribution of trapped particles in the inner magnetosphere and has an eastward flowing inner and westward flowing outer components. In addition to the symmetric ring current, an asymmetric partial ring current is taken into account with closing Region 2 sense field-aligned currents. Magnetopause currents are varied in accordance with solar wind dynamic pressure variations. Three moderate geomagnetic storms when <i>D<sub>st</sub></i> reached about –150 nT and one big storm with <i>D<sub>st</sub></i> about –250 nT are modelled. The model free parameters are specified for each time step separately using observations from GOES 8 and 9, Polar, Interball and Geotail satellites and <i>D<sub>st</sub></i> measurements. The model gives a high time-resolution field representation of the large-scale magnetic field, and a very good reproduction of the <i>D<sub>st</sub></i> index. It is shown that the ring current is most important during intense storms, whereas the near-Earth tail currents contribute more to the <i>D<sub>st</sub></i> index than the ring current during moderate storms.<br><br> <b>Key words.</b> Magnetospheric physics (Current systems; Magnetospheric configuration and dynamics; Storms and substorms)https://www.ann-geophys.net/22/1317/2004/angeo-22-1317-2004.pdf |
| spellingShingle | N. Yu. Ganushkina T. I. Pulkkinen M. V. Kubyshkina H. J. Singer C. T. Russell Long-term evolution of magnetospheric current systems during storms Annales Geophysicae |
| title | Long-term evolution of magnetospheric current systems during storms |
| title_full | Long-term evolution of magnetospheric current systems during storms |
| title_fullStr | Long-term evolution of magnetospheric current systems during storms |
| title_full_unstemmed | Long-term evolution of magnetospheric current systems during storms |
| title_short | Long-term evolution of magnetospheric current systems during storms |
| title_sort | long term evolution of magnetospheric current systems during storms |
| url | https://www.ann-geophys.net/22/1317/2004/angeo-22-1317-2004.pdf |
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