JapaneseGEMSIS-Ionosphere
Inductive Model of Global Electric Potential
We have developed an inductive scheme for the purpose of reconstructing the storm-time electric potential using data from the SuperDARN radars, including data from the recently developed SuperDARN Hokkaido radar. The Hokkaido radar covers a wide range of area from middle to high latitudes, enabling us to observe the wide spread distribution of the storm-time electric potential.
With data from the SuperDARN radars and ground-based magnetic observatories, an inductive model of the electric potential has been developed to reconstruct the electric potential during magnetic storms.
In addition to the modeling, observations were made for the storm-time convection electric field in the inner to outer magnetosphere on the nightside using THEMIS data. This study provided observational evidence that convection electric fields of different properties coexist and occupy spatially adjacent regions with sharp boundaries during a storm main phase.
Ionospheric Convection and Fast Flows in the Magnetotail
A statistical study was undertaken in order to understand how fast plasma flows, often occurring in the magnetotail, couple to ionospheric convection/electric fields, by combining satellite observations with their conjugate SuperDARN observations on the ground. The statistics revealed that magnetotail flows induce ionospheric flows with flow shears in some cases, or without shears in others.
Response of the Ionospheric Convection to the Interplanetary Magnetic Field
The research work focused on the temporal evolution of ionospheric flows in the auroral to subauroral latitude ionosphere, primarily by utilizing the SuperDARN data. Detailed examination of the SuperDARN data has clarified that significant antisunward flows emerge on the lower latitude side of the auroral oval in association with IMF northward turnings following weak southward IMF periods. This implies that the partial ring current and associated Region-2 type field-aligned current system has evolved even under a weak southward IMF condition.