Pl. Blelly et D. Alcayde, ELECTRON HEAT-FLOW IN THE AURORAL IONOSPHERE INFERRED FROM EISCAT-VHFOBSERVATIONS, J GEO R-S P, 99(A7), 1994, pp. 13181-13188
At auroral latitudes the electron heat flow resulting from solar EUV h
eating, as well as magnetospheric energy input, are important paramete
rs which drive the thermal electron structure of the upper ionosphere.
A method is presented which allows a determination from EISCAT-VHF ob
servations of the heat flow at two altitudes, typical of the collision
-dominated F2 region and of the topside ionosphere. EISCAT midwinter a
nd near-summer observations are used to illustrate the method: diurnal
and seasonal variations of solar origin are evidenced, with peculiar
enhancements at sunrise and sunset that are interpreted as a delay bet
ween the F2 level and topside terminator passage. Perturbations of mag
netospheric origin are then discussed. One of them is characteristic o
f low-altitude energy inputs. Others correspond to high-altitude energ
y inputs through heat flow variations and are interpreted as upward cu
rrents of the order of 14 muA m-2.