Evolution of Open Magnetic Flux and Heliospheric Current Sheet-associated Streamer Wind Across Multiple Solar Cycles

During the solar minima of solar cycles 23 and 24, the heliospheric magnetic field and the solar wind were observed to behave much differently than expected. In particular, previous studies showed that the magnetic open flux of the Sun, calculated as the product of the radial component of the Sun’s magnetic field and the squared radial distance from the Sun, was observed to have decreased along with observed changes in solar wind streams, such as solar wind proton density. This was in contrast to the standing theory that the “baseline” of the magnetic open flux should remain constant across the minima. In this work, we examine a range of solar wind parameters across five solar minima in cycles 21, 22, 23, 24, and 25. Using measurements of the heliospheric magnetic field and solar wind proton dynamic data (e.g., proton speed) and heavy ion composition (including charge state and elemental abundances) from the Advanced Composition Explorer (ACE), Geotail, International Sun-Earth Explorer-3 (ISEE-3), Explorer 50 (IMP-8), Wind, and Solar Orbiter spacecraft, we show that these parameters, with special focus on the magnetic open flux, have evolved differently with the solar cycle. In addition, we investigate the width of the Heliospheric Current Sheet (HCS) streamer belt in the recent solar cycle 25 solar minimum using ACE Solar Wind Ion Composition Spectrometer (SWICS) (1.1 and 2.0) and Solar Wind Electron, Proton and Alpha Monitor (SWEPAM) data. With this analysis, we validate the conservation of the Total Open Magnetic Flux (TOMF) proposed in Zhao & Fisk (2011). We also investigate the width of the HCS-streamer belt for the solar cycle 22 minimum. We will summarize our results and discuss the implications on validating the model of the Sun’s open magnetic flux transport proposed in Fisk (2005).