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 L-PP s) and both solar wind parameters and geomagnetic indices (thereafter L-PP 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 (T-lag s) and second at high T-lag 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.