17:15 〜 18:45
[PEM10-P03] Inconsistent Seasonal Variations of the IHFAC at the Morning Sector Observed by the Satellite and Ground Observations
キーワード：IHFAC、Sq電流系
The IHFAC (Inter-Hemispheric Field Aligned Current) is considered to be caused by the inhomogeneity of the potential in the dayside ionosphere, which is dominantly produced by the tidal motion of the neutral wind in the upper atmosphere. In the previous studies, the IHFAC is flowing northward (southward) at the noon (morning) sectors in both the northern summer and autumn, whereas the direction of the IHFAC at the evening sector has uncertainty regardless the season.
In this study, we analyze the magnetic variation data of Magnetic Field (VMF) onboard the Swarm satellites and from the ground stations of MAGDAS organized by Kyushu University. The magnetic data of the VMF were selected in the condition that the position of the satellites is within -5 to 5 degrees in latitude and within 115 to 135 degrees in longitude, where is the just above the DAV station from MAGDAS. In order to evaluate the current intensity and direction in the vertical direction, the eastward component of the magnetic variations is compared between the satellite and the ground.
At the noon sector, the in tensity of eastward component observed by SWARM shows obvious seasonal variations the maximum amplitude of ~20nT in the summer. This is quite consistent with that is observed at DAV. On the other hand, at the morning sector, the east component of magnetic variations observed by SAWRM does not show any clear seasonal dependence, whereas the clear seasonal variations are observed at DAV.
This result indicates that the current source of the IHFAC at the morning sector is quite different that at noon sector. In this paper, we will discuss the possible interpretation of the result of the analysis in terms of the 3D structure of the IHFAC current system.
In this study, we analyze the magnetic variation data of Magnetic Field (VMF) onboard the Swarm satellites and from the ground stations of MAGDAS organized by Kyushu University. The magnetic data of the VMF were selected in the condition that the position of the satellites is within -5 to 5 degrees in latitude and within 115 to 135 degrees in longitude, where is the just above the DAV station from MAGDAS. In order to evaluate the current intensity and direction in the vertical direction, the eastward component of the magnetic variations is compared between the satellite and the ground.
At the noon sector, the in tensity of eastward component observed by SWARM shows obvious seasonal variations the maximum amplitude of ~20nT in the summer. This is quite consistent with that is observed at DAV. On the other hand, at the morning sector, the east component of magnetic variations observed by SAWRM does not show any clear seasonal dependence, whereas the clear seasonal variations are observed at DAV.
This result indicates that the current source of the IHFAC at the morning sector is quite different that at noon sector. In this paper, we will discuss the possible interpretation of the result of the analysis in terms of the 3D structure of the IHFAC current system.