10:45 〜 12:15
[PEM10-P14] Characteristics of the latitudinal position of the SAPS structure using the SuperDARN Hokkaido Pair of radars
キーワード：SuperDARN、Sub-auroral polarization streams、Hokkaido Pair of radars、magnetosphere-ionosphere coupling
Sub-Auroral Polarization Streams (SAPS) are fast flows equatorward of the auroral precipitation region and are one of the most outstanding phenomena in the subauroral ionosphere. Its position provides crucial information for studying the intensity/size of the global ionospheric convection. The latitudinal distribution of SAPS is studied based on the over ten years of observation achieved by the SuperDARN Hokkaido Pair of radars, which are located at the lowest geomagnetic latitudes (< 40 degrees geomagnetic latitude) among the SuperDARN radars. Multi-event study shows that the latitude of the SAPS structure does not always follow the empirical relationship, which could determine the latitude of the SAPS structure as a function of the Dst index and magnetic local time. For example, a detailed analysis of the geomagnetic storm event on Sep 8, 2017, indicates that the SAPS position is located at a significantly lower geomagnetic latitude than the statistically expected position, even though the magnetic local time and Dst geomagnetic activity effects are considered. Possible factors responsible for such an unusual position, including the history of the IMF and the solar wind parameters and occurrence of substorms, will be discussed.