Incoherent scatter measurements ofEregion conductivities and currents in the auroral zone

Data taken by the incoherent scatter radar facility at Chatanika, Alaska, have been used to investigate ionospheric conductivities and electrical currents. During quiet days the conductivities appear to vary in a way consistent with ionization arising from solar EUV radiation. At these times the ratio between the height-integrated Hall and Pedersen conductivities is close to 2. In the evening hours, enhancements in the northward electric field are found to precede small increases in the conductivities that, from analysis of electron density profiles, arise from precipitation of 3–10×106 el cm−2 s−1 sr−1 in the energy range 3–20 keV. Strong enhancements of the Hall conductivity relative to the Pedersen conductivity occur during negative bays when the electric field is in a southwestward direction. These enhancements are caused by a relatively strong flux of 1–3×107 el cm−2 s−1 sr−1 in the energy range 15–20 keV. The ionospheric currents calculated in the geomagnetic east-west direction are in good agreement with the H component measured by a nearby magnetometer; this result indicates that the current causing the ground level magnetic fluctuations is a broad horizontal sheet current. The north-south ionospheric current, however, consistently disagrees with the observed D component in a manner that cannot easily be explained unless currents parallel to the earth's magnetic field are present. The parallel currents needed in daytime, however, are directed opposite to the Sqp current system, often inferred to explain the quiet day variations in auroral zone magnetograms. Finally, it is found that the neutral wind is of considerable importance in driving currents during quiet days in the auroral zone. Often these wind-driven currents oppose the current driven by the static electric field.