Magnetospheric convection and the high-latitudeF₂ionosphere

Abstract

Behavior of the polar ionospheric F-layer as it is convected through the cleft, over the polar cap and through the night side F-layer trough zone is investigated. Passage through the cleft adds of the order of 2 x 10 s ions cm" 3 in the vicinity of the F 2 peak and redistributes the ionization above approximately kdO km altitude to conform with an increased electron temperature. The redistribution of ionization above kOO km altitude forms the "averaged" Plasma ring seen at 1000 km altitude.The F-layer is also raised of the order of 20 km in altitude by the convection electric field. The time required for passage across the polar cap (25°) is about the same as that required for the F-layer peak concentration to decay by e. The F-layer response to passage through the night side soft electron precipitation zone should be similar to but less than its response to passage through the cleft. The exception is that the layer will be lowered in altitude by the convection electric field.

Statistical analysis of ionospheric mid-latitude trough over the Northern Hemisphere derived from GPS total electron content data

“…Several mechanisms have been proposed to explain the trough in the pre-midnight sector. The first mechanism is plasma stagnation and decay of ionization in darkness in a region where corotation and convection electric fields counteract each other (e.g., Knudsen 1974;Spiro et al 1978;Collis and Häggström 1988;and Hedin et al 2000). Another mechanism for the trough formation during periods of enhanced geomagnetic activity is related to large poleward electric field events, which are also called subauroral ion drifts (SAIDs).…”

On the diurnal variability in F2-region plasma density above the EISCAT Svalbard radar

“…Knudsen (1974) suggested that F region plasma convected through the cusp to flow across the polar cap from midday towards night side auroral latitudes, would lead to a tongue of enhanced ionization across the polar cap (TOI).…”

Spatial structure of summertime ionospheric plasma near magnetic noon

“…In this instance, it was suggested that there may be sufficient time for the plasma density to build-up if sunward convecting fluxtubes move along the cusp region for tens of minutes before turning anti-sunward into the polar cap. However, it is now widely accepted that the bulk of the ionisation within the polar cap originates from the transport of photoionisation from sub-auroral latitudes, and not direct soft particle precipitation in the vicinity of the cusp (Knudsen, 1974;Kelly and Vickrey, 1984;Whalen, 1994). Foster (1984) presented average maps of convection and F-region electron density at auroral latitudes from the Chatanika radar.…”