Publication Date:
2015-07-08
Description:
Previous studies suggested that electric and/or magnetic field fluctuations observed in the nighttime topside ionosphere at mid-latitudes generally originate from quiet-time nocturnal medium-scale traveling ionospheric disturbances (MSTIDs). However, decisive evidences for the connection between the two have been missing. In this study we make use of the multi-spacecraft observations of mid-latitude magnetic fluctuations (MMFs) in the nighttime topside ionosphere by the Swarm constellation. The analysis results show that the area hosting MMFs are elongated in the NW-SE (NE-SW) direction in the northern (southern) hemisphere. The elongation direction and the magnetic field polarization support that the area hosting MMFs are nearly field-aligned. All these properties of MMFs suggest that they have close relationship with MSTIDs. Expectation values of root-mean-square (RMS) field-aligned currents (FACs) associated with MMFs are up to about 4 nA/m 2 . MMF coherency significantly drops for longitudinal distances of ≥1°.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics