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| Natura: | Artículo científico |
| Lingua: | en |
| Pubblicazione: |
Sociedade Brasileira de Física
2004
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| Accesso online: | https://www.redalyc.org/articulo.oa?id=46434808 |
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Sommario:
- Great geomagnetic storms in the rise and maximum of solar cycle 23 A. Dal Lago A. L. Gonzalez L. Balmaceda A. de Lucas L. E. A. Vieira E. Echer W. D. Gonzalez F. L. Guarnieri M. R. da Silva J. Santos N. J. Schuch Física, Astronomía y Matemáticas Geomagnetic storms are intervals of time when a sufficiently intense and long-lasting interplanetary convectionelectric field leads, through a substantial injection of energy into the magnetosphere-ionosphere system, to an intensified ring current, strong enough to exceed some key threshold of the quantifying storm time Dst index.We have studied all the 9 great magnetic storms (peak Dst < -200 nT) observed during the rise and maximum ofsolar cycle 23 (from 1997 to early 2001), in order to identify their solar and interplanetary causes. Apart of onestorm occurred during the period without observations from the Solar and Heliospheric Observatory (SOHO),all of them were related to coronal mass ejections observed by the Large Angle and Spectroscopic Coronagraph(LASCO). The sources of interplanetary southward magnetic field, Bs, responsible for the occurrence of thestorms were related to the intensified shock/sheath field, interplanetary magnetic clouds field, or the combination of sheath-cloud or sheath-ejecta field. It called our attention the fact that one of the events was related to a slow CME, with CME expansion speed not greater than 550 km/s. The purpose of this paper is to address the main sources of large geomagnetic disturbances using the current satellite capability available. As a general conclusion, we found that shock/sheath compressed fields are the most important interplanetary causes of great magnetic storms during this period. 2004 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46434808 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.4B Vol.34