Plasma convection and auroral precipitation processes associated with the main ionospheric trough at high latitudes

摘要: Abstract Intervals of F -region electron density depletions associated with the main (mid-latitude) ionospheric trough have been studied using latitude scanning experiments EISCAT UHF radar. From 450 h measurements over a one year period at solar minimum (April 1986–April 1987) local time appearance given is observed to vary by up about 8 h. No seasonal dependence location apparent, but troughs are absent in data from summertime experiments. A weak on K p found, and an empirical model predicting proposed. The shown be more appropriate than other available quantitative models for latitudes covered EISCAT. Detailed studies four individual days show no relationship between magnetic activity observation trough. On all these days, however, edge auroral oval, evidenced enhanced densities E -region, found approximately co-located with, or 1° poleward of, minimum. Simultaneous ion drift velocity that region strong (> several hundred metres per second) westward flow, its boundary located 1°–2° equatorward Within accuracy observations this convection boundary, precipitation independent latitude. relevance results discussed relation theoretical -reregion high latitudes.