North‐south asymmetry of the location of the heliospheric current sheet revisited

Abstract

The possible latitudinal offset of the location of the heliospheric current sheet (HCS) is an important question, since it has impact on the understanding of various phenomena including the solar dynamo and the modulation of cosmic rays. In the declining phase of the previous, 22nd solar cycle, in 1993, a southward displacement of the HCS by 10° was proposed to explain the north‐south asymmetry of energetic charged‐particle fluxes measured by Ulysses. Other observations supported the north‐south asymmetry as well, and it is now widely accepted by the scientific community that in 1993, the HCS was displaced 10° southward. However, in reality, the Ulysses magnetic field measurements did not give direct evidence for such a large displacement of the HCS. Here we revisit the question and extend our previous study for the declining phase of solar cycle 23 as well. Careful analysis of the HCS crossings observed by Ulysses during the fast latitude scans shows that a southward displacement of the HCS by 2°–3° is possible and consistent with the data for cycles 22 and 23. The impact of the HCS location on the latitudinal gradients of energetic particle fluxes is discussed.