An EMHD soliton model for small‐scale magnetic holes in magnetospheric plasmas

Small‐scale magnetic holes (SSMHs) in the magnetosphere plasma sheet are investigated in this paper. A developed electron magnetohydrodynamics (EMHD) soliton model is proposed as a new approach to SSMHs formation. The Biermann battery effect is taken into account in resolving the magnetic evolution equation with a slow‐mode solution in the weak nonlinear regime. Statistical investigation of SSMH observation data in the plasma sheet by Cluster is carried out in comparison with the theory. We apply multispacecraft data for distinguishing sheet‐like or cylindrical SSMHs observed and clarified by the solitary wave in the EMHD model. Furthermore, the major parameters, such as amplitude, width, maximum magnetic field perturbation, and perpendicular temperature variation of the SSMHs, are found consistent with the theoretical analysis. Key Points One‐dimensional and 2‐D KdV equations are derived to explain SSMHs in plasma sheet Both sheet‐like and cylindrical SSMHs are identified in observations The KdV soliton solutions consist with statistical observations