Bifractality and Cross-over Behavior Observed in Solar Wind Intermittency by Parker Solar Probe: Rank Ordered Analysis and Partition Function Approach

We verify the level of multifractality of the solar wind magnetic field fluctuations (energy density and components) measured by the Parker Solar Probe (PSP) during its first perihelion (01-09.11.2018), recently reported in literature. Two different complementary fractal approaches, namely the Rank Ordered Multifractal Analysis (ROMA, Chang and Wu 2008) and the Partition Function Multifractal Analysis (PFMA, Halsey et al. 1986) are applied, for the first time, on the same data set. ROMA considers the raw fluctuations at all scales, grouped according to their rank; PFMA provides a multifractal spectrum from a measure extracted from data and assumed to be the result of a multiplicative process. The methodology provides new insights on the multifractality close to the Sun (at 0.17-0.23 au), and complements other studies of the same dataset, at close distances from the Sun, and at solar minimum.At 0.17 au, a cross-over is identified at a narrow range of scales centered on ~4 s (corresponding to a spatial scale of ~1400 km) separating two sub-ranges of inertial scales, with different statistical and fractal properties. The cross-over is detected by four different approaches (1) flatness behavior, (2) structure functions power law scaling, (3) change of turbulence regime across the inertial range, (4) change of the ROMA spectra over the two inertial scale-ranges. Left-skewed asymmetry of PFMA multifractal spectra further supports the complexity of the underlying dynamics dominated by large fluctuations. Conversely, the lack of right-skewed multifractal spectra at 0.17 au, as detected in the outer heliosphere, underline the different state of fluctuations near the Sun. The results have been recently accepted for publication in the Astrophysical Journal (Teodorescu et al., 2026). Chang, T., & Wu , C.C. 2008, PhRvE, 77, 045401. doi:10.1103/PhysRevE.77.045401Halsey, T. C., Jensen, M. H., Kadanoff, L. P. et al. 1986, PhRvA, 33, 1141–1151. doi:10.1103/PhysRevA.33.1141Teodorescu, E., Wawrzaszek, E., Echim, M., 2026, ApJ, DOI: 10.3847/1538-4357/ae3185