Statistical Properties of Small-Scale Magnetic Flux Ropes in the Near-Earth Solar Wind

We present a statistical analysis of small-scale magnetic flux ropes (SMFRs) observed in the near-Earth solar wind using data from the Magnetospheric Multiscale (MMS) and Wind spacecraft, identified through an automated Grad–Shafranov reconstruction technique. A total of 2,355 events from MMS1 (2017–2023) and 26,305 from Wind (2004–2022) reveal that SMFRs exhibit characteristics typical of quiet solar wind conditions near 1 AU, have diameters below ∼150 (Formula presented.), and show axial orientations aligned with the Parker spiral. Their occurrence rates (∼1,350 events/year) remain steady without clear solar-cycle dependence, while the magnetic flux and magnetic field magnitude exhibit modest modulation with solar activity. No clear preferred spatial distribution of SMFR occurrence is identified in the near-Earth upstream region. Dynamic pressure variations associated with SMFR event onsets are small ((Formula presented.) nPa), implying that their geoeffectiveness arises primarily from internal magnetic configurations rather than dynamic pressure pulses. Overall, these findings suggest that SMFRs are not transient structures associated with strongly disturbed solar wind conditions, but rather intrinsic components of the solar wind.