[PEM16-P20] Polarization characteristics of Pc1 pearl structure observed at Kawatabi, Osaki, Miyagi prefecture
キーワード：Pc1, pearl, pulsation, ELF, magnetic variation, polarization
Pc1 geomagnetic pulsations are often found in the ELF magnetic field data obtained by two sets of induction magnetometers EL-12 constructed by Tierra Technica Co. Ltd, placed in North-South and East-West directions at Kawatabi, Osaki, Miyagi prefecture Japan. The magnetic latitude of the observation site is N30 and the L value is about 1.3.
Although the data coverage was not very good, we have found 7 examples of pearl structures, within the frequency range of 1 to 5 Hz. They showed temporal variation of bandwidth such as 0.3 to 1.2Hz, or 0.9 to 1.8 Hz, forming pearl structures in dynamic spectra. The frequency itself also varied with time: they rose in 3 cases found in pre-midnight, and fall in 4 cases in the pre-midnight region.
Polarization of the magnetic variation was examined by using Fourier components of N-S and E-W magnetic field components. We have 4 evens for which E-W and N-S observations were available. The polarization was steady and right-handed for one event, but for the rest, it was variable. One event showed left-handed polarization at higher frequency and right-handed in the lower. Other two events showed alternative polarizations pearl to pearl.
Although the data coverage was not very good, we have found 7 examples of pearl structures, within the frequency range of 1 to 5 Hz. They showed temporal variation of bandwidth such as 0.3 to 1.2Hz, or 0.9 to 1.8 Hz, forming pearl structures in dynamic spectra. The frequency itself also varied with time: they rose in 3 cases found in pre-midnight, and fall in 4 cases in the pre-midnight region.
Polarization of the magnetic variation was examined by using Fourier components of N-S and E-W magnetic field components. We have 4 evens for which E-W and N-S observations were available. The polarization was steady and right-handed for one event, but for the rest, it was variable. One event showed left-handed polarization at higher frequency and right-handed in the lower. Other two events showed alternative polarizations pearl to pearl.