caa a22 4500 445347023 CHVBK 20180317142832.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s11207-010-9657-6 doi (NATIONALLICENCE)springer-10.1007/s11207-010-9657-6 The Floor in the Solar Wind Magnetic Field Revisited [Elektronische Daten] [E. Cliver, A. Ling] Svalgaard and Cliver (Astrophys. J. Lett. 661, L203, 2007) proposed that the solar-wind magnetic-field strength [B] at Earth has a "floor” value of ≈4.6 nT in yearly averages, which is approached but not broached at solar minima. They attributed the floor to a constant baseline solar open flux. In both 2008 and 2009, the notion of such a floor was undercut by annual B averages of ≈4 nT. Here we present a revised view of both the level and the concept of the floor. Two independent correlations indicate that B has a floor of ≈2.8nT in yearly averages. These are i) a relationship between solar polar-field strength and yearly averages of B for the last four 11-year minima (B MIN), and ii) a precursor relationship between peak sunspot number for cycles 14 - 23 and B MIN at their preceding minima. These correlations suggest that at 11-year minima, B consists of i) a floor of ≈2.8nT, and ii) a component primarily due to the solar polar fields that varies from ≈0 nT to ≈3 nT. The solar polar fields provide the "seed” for the subsequent sunspot maximum. Removing the ≈2.8 nT floor from B MIN brings the percentage decrease in B between the 1996 and 2009 minima into agreement with the corresponding decrease in solar polar-field strength. Based on a decomposition of the solar wind (from 1972 - 2009) into high-speed streams, coronal mass ejections, and slow solar wind, we suggest that the source of the floor in B is the slow solar wind. During 2009, Earth was in slow solar-wind flows ≈70% of the time. We propose that the floor corresponds to a baseline (non-cyclic or ground state) open solar flux of ≈8×1013 Wb, which originates in persistent small-scale (supergranular and granular) field. Springer Science+Business Media B.V., 2010 Solar wind nationallicence Slow solar wind nationallicence Floor nationallicence Cycle 24 nationallicence Cliver E. Space Vehicles Directorate, Air Force Research Laboratory, Hanscom AFB, MA, USA aut Ling A. Atmospheric Environmental Research, Inc., Lexington, MA, USA aut Solar Physics Springer Netherlands 274/1-2(2011-12-01), 285-301 0038-0938 274:1-2<285 2011 274 11207 https://doi.org/10.1007/s11207-010-9657-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11207-010-9657-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Cliver E. Space Vehicles Directorate, Air Force Research Laboratory, Hanscom AFB, MA, USA aut NATIONALLICENCE 700 1- Ling A. Atmospheric Environmental Research, Inc., Lexington, MA, USA aut NATIONALLICENCE 773 0- Solar Physics Springer Netherlands 274/1-2(2011-12-01), 285-301 0038-0938 274:1-2<285 2011 274 11207 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer