IDENTIFICATION OF SOLAR FEATURES CAUSING GEOMA GEOMAGNE NET- TIC STORM DURING THE PERIOD OF 1996-2003

摘要

Abstract: A geomagnetic storm is a global disturbance in Earth’s magnetic field usually characte characterized by a ized main phase during which the horizontal component of the Earth’s low latitude magnetic field are signi significan cant- tly depressed over a time span of one to a few hours followed by a recovery phase that may extend over se ly sev- veral days. These magnetic storms generally occur due to abnormal conditions in the interplanetary ma eral magnetic netic field (IMF) and solar wind plasma emis emissions caused by various solar sions phenomenons phenomenons. In the present study geomagnetic storm events are characterized by the Disturbance storm time (Dst) index measured in terms of nano Tesla (nT) during the periods 1996 1996-2003. A storm is said to be weak if (Dst < 50 nT), Mo Moderate if (Dst51 erate Dst51-150nT), Intense/great if (Dst151nT 250nT), Super storm if (Dst > 251 nT).The present work deals with a complimentary question mainly referring to solar and inte interplanetary features that planetary causes very large and intense geomagnetic stor storms, for this purpose we have used the Dst index as an indic ms, indica- ator of geomagnetic activities, using which we have classified the storm event in to two categories i.e. tor Intense geomagnetic storm storms with Dst ≤ s -300 nT, and Supper intense storms with Dst index ≥ -301 nT.