The ionospheric signatures of rapid subauroral ion drifts

摘要: Subauroral ion drifts (SAID) are latitudinally narrow regions of rapid westward drift located in the evening sector and centered on equatorward edge diffuse aurora. Observations SAID as identified by meters Atmosphere Explorer C Dynamics B spacecraft utilized to determine their effect F region composition, relationship mid-latitude trough, temporal evolution. At altitudes near peak a deep ionization trough is formed large where O{sup +} concentration considerably depleted NO{sup enhanced, while at higher signature mitigated or even absent. have been observed last longer than 30 min but less 3 hours, latitudinal width often becomes narrower time progresses. The plasma flows more invariant latitude increases. Poleward SAID, flow is, average, throughout auroral zone evening, midnight it eastward.