The ULF wave in the pile-up and dipolarization process
通量堆积和偶极化过程中的超低频波动

A typical substorm process in the night-side near-Earth magnetotail company with the pile-up and depolarization process explored by TC-1 on sep 17,2004.We analyzed the FGM and HIA data(4s resolution)with wavelet and FFT analysis method to understand the low-frequency wave in the pile-up and dipolarization process.The analysis results showed that there are distinctly irregular low-frequency wave in the pile-up and dipolarization process,the main range of the wave frequency is 4~15 mHz,coincident with the Pi-2 pulse.The LF wave of the each magnetic field component in the dipoarization process is distinctly different with that in the pile-up process.During the pileup and dipolarization process,the wave of the temperature and velocity in the direction parallel to the magnetic field is distinctly with that in the direction perpendicular to the magnetic field.It seems the wave of the temperature and velocity in the direction parallel to the magnetic field has good correlation,and the wave of the ions density has good correlation with the wave in the direction parallel to the magnetic field,which means there exist compressive wave in the direction parallel the magnetic field.The exploration by the TC-1 showed that there are distinct increase of the By component in the pile-up process.The ULF wave has closely correlation with increase By component,and may has important effect of the substorm onset.