Estudo de estruturas geoefetivas no meio interplanetário e de suas causas solares. / Study of the interplanetary geoeffective structures and their solar origins

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In this work we have studied geoeffective interplanetary structures observed near earth and their solar origins, involving several basic and applied scientific aspects, related to the research area named Space Weather. We present a study of the coronal mass ejections (CME) observed at the sun by the LASCO instrument, in the period of January 1997 to April 2001. We have studied the CME dynamics near the sun using a new image processing technique. We have defined the CME lateral expansion speed, which is the growth rate perpendicular to the main CME movement direction, concluding that it is empirically related to the radial CME speed. This result allowed us to use the halo CME expansion speed to predict its travel time to the earth, as well as to predict some of its characteristics. We have studied the interplanetary structures related to the CMEs observed during the period, finding 92 univocal CME-interplanetary correspondences, from which 38 had an ejecta structure, and whose interplanetary speeds were related to the corresponding halo CME expansion speed. Using these CME-interplanetary speed measurements we calculated the CME average acceleration from the sun to 1AU, which shows a strong evidence of solar wind influence in this process. From a study of interplanetary magnetic clouds interacting with high speed streams we conclude that interplanetary effects can increase geoeffectiveness substantially. A new model for 1 AU CME travel time prediction was then proposed using our new concept of halo CME expansion speed, which gave good prediction results, with average error of the order of + 28h. We have constructed a peak Dst prediction scheme, which is valid for magnetic clouds, with good results. Finally, we present a study of the complete set of data from three different points of view: (1) from the sun; (2) from the interplanetary medium, at 1 AU; and (3) from the Earth magnetosphere, in the light of the geomagnetic storms. A detailed analysis of the 9 super storms of the period, Dst < -200 nT, from the solar observations to the interplanetary observations at 1 AU was performed, pointing out the causes of the storms.

ASSUNTO(S)

interação sol-terra clima espacial ejeção de massa coronal nuvens magnéticas meio interplanetário física solar tempestades geo(magnéticas coronógrafos vento solar

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