The North-South Asymmetry of the Interplanetary Magnetic Helicity Generator Function

C. W. Smith and J. W. Bieber

Proceedings of Solar Wind 8, in press (1996)

Abstract:

Previous analyses of the north-south asymmetry of the interplanetary magnetic helicity using the omnitape dataset have shown that there exists a persistent and statistically significant asymmetry in the helicity at 1 AU. The asymmetry is concentrated in fluctuations with spacecraft frame timescales less than 30 hours. We have extended these analyses to include data collected in the outer heliosphere where we are required to consider spacecraft frame timescales significantly greater than 30 hours. This shift in timescales is consistent with the rotation of the Parker spiral. We show the results from our studies of the Pioneer 10 & 11 datasets which demonstrate a north-south asymmetry of the magnetic helicity consistent with that seen in the inner heliosphere. Suggestive evidence of the selective decay of magnetic helicity is also presented. The asymmetry between the magnetic helicity of the two hemispheres has significant and measurable implications for cosmic ray propagation and these implications are reviewed briefly in light of the new results.