An extended study of the source, characteristics, and geoeffectiveness of the Interplanetary Magnetic Field Southward component at different distances from the Sun

Most (~75%) long-duration, large-amplitude southward Interplanetary Magnetic field (IMF Bs) intervals are associated with well-defined solar wind structures such as ICMEs and CIRs. Here IMF Bs intervals unrelated to such solar wind structures at 1 AU are examined in detail using plasma and magnetic field data from ACE. We also extend our study of IMF Bs to different heliocentric distances and latitudes using data from Ulysses and Helios. Using ACE observations, we find that low-frequency Alfvén waves in the slow solar wind are a possible source of IMF Bs intervals (t > 3 hours, Bz < -5 nT), and that Alfvén wave-related Bs intervals are geoeffective. We find that the contribution of Bs intervals from ICMEs decreases significantly with radial distance due to their over-expansion. This means that CIR-related Bs intervals dominate at 5.3 AU.