Solar and interplanetary causes of very intense geomagnetic storms

✍ Scribed by W.D. Gonzalez; A.L. Clúa de Gonzalez; J.H.A. Sobral; A. Dal Lago; L.E. Vieira

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 242 KB
• Volume: 63
• Category: Article
• ISSN: 1364-6826
• DOI: 10.1016/s1364-6826(00)00168-1

✦ Synopsis

The dominant interplanetary phenomena causing intense magnetic storms are the interplanetary manifestations of fast coronal mass ejections (CMEs). Two interplanetary structures are important for the development of such class of storms, involving an intense and long duration Bs component of the IMF: the sheath region just behind the forward shock, and the CME ejecta itself. Frequently, these structures lead to the development of intense storms with two-step growth in their main phases. These structures also lead sometimes to the development of very intense storms, especially when an additional interplanetary shock is found in the sheath plasma of the primary structure accompanying another stream. The second stream can also compress the primary cloud, intensifying the Bs ÿeld, and bringing with it an additional Bs structure. Thus, at times very intense storms are associated with three or more Bs structures. We also discuss evidence that magnetic clouds with very intense core magnetic ÿelds tend to have large velocities, thus implying large amplitude interplanetary electric ÿelds that can drive very intense storms.