Evolution and nature of north-south asymmetry in the heliospheric current sheet

✍ Scribed by T. E. Girish; S. R. Prabhakaran Nayar

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 504 KB
• Volume: 125
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00158415

✦ Synopsis

The nature and evolution of north-south asymmetry in the heliospheric current sheet (HCS) has been investigated using solar and interplanetary magnetic field (IMF) observations for the past few solar cycles. The mean heliographic latitude of the HCS (averaged over the solar longitude) '%' is found to be non-zero during many solar rotations indicating that the large-scale solar magnetic field is more ordered in a system where the origin is shifted away from the centre of the Sun. We have shown that the asymmetry in HCS manifests in different forms depending on the transition heliographic latitude of the reversal of dominant polarity of the IMF (Or) and the difference in the maximum latitudinal extension of the HCS in the two solar hemispheres (A). The classification of the observed asymmetry during 1971-1985 and its effect on IMF observations near Earth has been studied. We have also inferred the sign of Or during 1947-1971 using inferred IMF polarity data. The observed sign reversals of O r suggest the importance of periodicities less than the solar cycle period to be associated with the evolution of asymmetry in HCS. Asymmetry in sunspot activity about the solar equator does not seem to relate consistently well with the asymmetry in HCS about the heliographic equator.