Evidence of MLT propagation of the plasmapause inferred from THEMIS data

The cross-correlation analysis is applied to the comprehensive database of THEMIS plasmapause crossings (6840 LPP s) and both solar wind parameters and geomagnetic indices (thereafter LPP indicators). We estimate MLTs of the plasmapause formation and further monitor the motion of the new plasmapause at high MLT resolution. Our results show that plasmapause is firstly formed within 23-07 MLT and then propagates around the Earth with the velocity estimated to amounts for 1.10 and 0.45 of the corotation velocity in sectors 07-15 MLT and 15-23 MLT, respectively. Two branches within 23-07 MLT are identified, one at low time lags (Tlag s) and second at high Tlag s which we relate to the formation of the new plasmapause and to the propagation of the plasmapause formed one MLT-cycle before. This study can be used to improve the current understanding of the plasmapause formation and propagation.