Dual-Channel Energy and Mass Coupling Between the Solar Wind and Magnetotail Plasma Sheet: Insights From Machine Learning-Based Partitioning

Utilizing joint observations from the Magnetospheric Multiscale (MMS) and OMNI spanning from 2017 to 2021, we investigate the response of the Earth's plasma sheet (PS) to solar wind (SW) forcing. The PS is divided into three key regions in the downtail (X < −10 R_E, Geocentric Solar Magnetospheric), that is, the current sheet (CS), central plasma sheet (CPS), and plasma sheet boundary layer, using a hybrid filter–decision tree model (HFDTM). The PSs of different regions were analyzed under four upstream SW speed and interplanetary magnetic field (IMF) conditions: low-speed northward (LSNW), low-speed southward (LSSW), high-speed northward (HSNW), and high-speed southward (HSSW). For each regime, we perform a comprehensive statistical analysis of key physical parameters, including the convective electric field (E_CY), kinetic electric field (E_K), and ion density (n_i) and temperature (T_i). Our main finding are as follows: (a) Ec_Y in the plasma sheet shows a monotonic increase with rising SW–E_CY0 across all 3 PS regions under southward IMF, but ambiguous correlation with SW under northward IMF; (b) n_i shows a strong correlation with the solar wind under both IMF orientations, particularly during low-speed conditions; and (c) E_K and T_i consistently display weak correlations across all regimes, highlighting the dominant role of internal processes in plasma sheet evolution. These results support a dual-path coupling mechanism between the solar wind and the magnetosphere, characterized by persistent mass loading across all regimes, and an energy transfer pathway that is strong under the southward IMF but weak and primarily governed by internal energy relaxation processes under northward IMF.