Profiles of electron temperature and B_z along Earth's magnetotail

Abstract. We study the electron temperature distribution and the structure of the current sheet along the magnetotail using simultaneous observations from THEMIS spacecraft. We perform a statistical study of 40 crossings of the current sheet when the three spacecraft THB, THC, and THD were distributed along the tail in the vicinity of midnight with coordinates X_B ∈ [−30 R_E, −20 R_E], X_C ∈ [−20 R_E, −15 R_E], and X_D ~ −10 R_E. We obtain profiles of the average electron temperature ⟨T_e⟩ and the average magnetic field ⟨B_z⟩ along the tail. Electron temperature and ⟨B_z⟩ increase towards the Earth with almost the same rates (i.e., ratio ⟨T_e⟩/⟨B_z⟩ ≈ 2 keV/7 nT is approximately constant along the tail). We also use statistics of 102 crossings of the current sheet from THB and THC to estimate dependence of T_e and B_z distributions on geomagnetic activity. The ratio ⟨T_e ⟩/⟨B_z⟩ depends on geomagnetic activity only slightly. Additionally we demonstrate that anisotropy of the electron temperature ⟨T_∥/T_⊥⟩ ≈ 1.1 is almost constant along the tail for X ∈ [−30 R_E, −10 R_E].