Analisys of interplanetary structures associated with cosmic ray precursory anisotropies and intense geomagnetic storms
Abstract
Throughout the 11 year solar cycle a number of energetic phenomena such as "flares" and coronal mass ejections (CME) give rise at earth to the so-called magnetic storms. These storms are characterized by a decrease in the H component of terrestrial magnetic field, lasting some dozens of hours. They are associated to interplanetary structures whose interplanetary magnetic field component in the Z direction (Bz) is southward, i.e., antiparalell to the earth's magnetic field direction. Thus, the interplanetary magnetic field interconnects with the geomagnetic field causing energy to be transported inwards. Some of these structures are associated with precursory anisotropy observed in ground cosmic ray data (muons). The objective of this work is to use a set of intense geomagnetic storm events (Dst<-100nT), already studied by Munakata et al (2000) in terms of cosmic ray signatures, and identify their interplanetary structures using observations made by ACE, Wind and IMP-8 satellites. We use the following interplanetary data: plasma (solar wind speed , density and temperature of protons), interplanetary magnetic field (B, Bx, By, Bz), observed by IMP-8, WIND and ACE satellites, and Dst index from Kyoto to characterize the storms.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.1431S