Statistical Properties of Small-scale Linear Magnetic Holes in the Martian Magnetosheath

Abstract

The small-scale linear magnetic hole (LMH) is a magnetic dip with a size less than or on the order of ρ i (proton gyroradius), which may contribute to turbulence properties in the solar wind and other astrophysical plasmas. Based on one-month measurements of the Mars Atmosphere and Volatile EvolutioN mission, 174 small-scale LMH events in the Martian magnetosheath are used to investigate their statistical properties in this study. Our results show that small-scale linear LMHs are ubiquitous in the Martian magnetosheath, and their occurrence rate is estimated to be approximately 1.5 events per hour based on one-month observations. Compared with the ambient plasma, the averaged magnitude of the magnetic field in these holes can decrease from 6.8–3.5 nT. Nearly 66% of events have a B min / B value in the range of (0.45, 0.75). The duration of small-scale MHs is mainly less than 0.4 s. For 90% of the events, the size along the solar wind flow is less than ρ i . As the rotation angle increases, the occurrence rate of small-scale LMHs decrease. However, the B min / B , size, and duration of small-scale LMHs have no obvious dependence on their rotation angle.