Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds
We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the aver...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2006-12-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/24/3383/2006/angeo-24-3383-2006.pdf |
| Summary: | We investigated geomagnetic activity which was induced by interplanetary
magnetic clouds during the past four solar cycles, 1965–1998.
We have found that the intensity of such geomagnetic storms is more severe
in solar maximum than in solar minimum.
In addition, we affirm that the average solar wind speed of magnetic clouds is
faster in solar maximum than in solar minimum.
In this study, we find that
solar activity level plays a major role on the intensity of geomagnetic storms.
In particular, some new statistical results are found and listed as follows.
(1) The intensity of a geomagnetic storm in a solar active period is
stronger than in a solar quiet period.
(2) The magnitude of negative <i>Bz</i><sub>min</sub> is larger in a solar active
period than in a quiet period.
(3) Solar wind speed in an active period is faster than in a quiet period.
(4) <i>VBs</i><sub>max</sub> in an active period is much larger than in a quiet period.
(5) Solar wind parameters, <i>Bz</i><sub>min</sub>, <i>V</i><sub>max</sub> and <i>VBs</i><sub>max</sub> are
correlated well with geomagnetic storm intensity, <i>D</i><sub>st<sub>min</sub></sub> during
a solar active period.
(6) Solar wind parameters, <i>Bz</i><sub>min</sub>, and <i>VBs</i><sub>max</sub> are not correlated
well (very poorly for <i>V</i><sub>max</sub>) with geomagnetic storm intensity during
a solar quiet period.
(7) The speed of the solar wind plays a key role in the correlation of
solar wind parameters vs. the intensity of a geomagnetic storm.
(8) More severe storms with <i>D</i><sub>st<sub>min</sub></sub>≤−100 nT caused by MCs
occurred in the solar active period than in the solar quiet period. |
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| ISSN: | 0992-7689 1432-0576 |