a) FIELDS magnetic field data in RTN coordinates. The magnitude, |B|, is shown in black. b) Radial component of magnetic field normalized to field magnitude B_R/|B|. Large-scale inversions in B_R known as SBs are observed. c) SWEAP SPAN velocity measurements in RTN coordinates. |V| is shown in black. d) Computed dHT frame speed, V_dHT, Alfvén speed, V_A, and average wind speed, V_sw, and η = (V_A/V_sw)².