Determination of low-latitude electric fields from FUV images
Abstract
Images of the nighttime equatorial airglow arcs are currently being obtained by the far-ultraviolet imager (FUV) onboard the NASA IMAGE satellite. Of all the nightside FUV emissions, the spectrographic imager (SI) is sensitive only to the 135.6-nm emission of O I, produced upon recombination of ionospheric oxygen ions to produce the neutral atom. Imaging periods lasting several hours about the time of satellite apogee allow for the determination of the velocity of drifting plasma density depletions (spread-F) occurring within the airglow arcs. These velocities reflect the ExB drift of low-latitude plasma, under the influence of a vertical electric field. These drift speeds are also self-consistently associated with F-region neutral wind magnitudes. A survey of several months of data produces information regarding the range of electric fields observed, and the spatial and temporal frequency of the appearance of plasma depletions. Also, it is found that spread-F plasma depletions are observed during >80% of the successive 4-6 hour imaging periods, with absences mainly during periods of high magnetic activity.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....4203I