The Equatorial Electrojet

The delayed occurrence of equatorial ionospheric F2 layer post-sunset height decreases following auroral-zone substorm onsets

“…3 and 4 of Fejer et al (2008) illustrate these variations for a range of longitudes. As before (Fejer, 2002), the equinoctial events are larger than the events during the June solstice and they increase with solar flux variations consistent with those expected for the electrojet (Reddy, 1989;Bowman and Mortimer, 2009). This suggests that westward electric fields may be associated with these downward movements.…”

Seasonal characterization of the equatorial electrojet height rise over Brazil as observed by the RESCO 50MHz back-scatter radar

“…Transient events which occur under disturbed condition, such as the prompt penetration of magnetospheric electric fields to the equatorial region also serve as a source of large variability in the EEJ processes. See, for example, Reddy (1989) and Abdu et al (2003). In order to quantify the rising feature of the EJC we used an exponential fitting of the form h ¼ h 0 þ xe Dt=t (with the scale unit x being equal to 1 km) for the EJC curves, restricted to the period between 1400 and 1700 LT.…”

“…The equatorial electrojet (EEJ) is an eastward current sheet that flows in the ionospheric plasma at the E layer heights between about 90 and 120 km centered at the magnetic equator and extends in a zone of about 600 km in the north-south direction (Forbes, 1981;Reddy, 1989). The EEJ current can drive plasma instabilities leading to the formation of field-aligned plasma irregularities.…”

Local time and longitude dependence of the equatorial electrojet magnetic effects

“…Most of the ÿrst studies were carried out to explain the generating mechanism of such an intense current ow along the dip-equator (Baker and Martyn, 1953;Chapman and Bartels, 1940). Since the 1970s, some theories and physical models of the ionospheric dynamo have been developed (Sugiura and Cain, 1966;Untiedt, 1967;Sugiura and Poros, 1969;Richmond, 1973;Stening, 1985;Reddy, 1989) in order to explain the mechanism of the EEJ ow and its main features (day to day, seasonal variability, counter-electrojet, electrodynamic processes of coupling with global scale current systems, etc). Another approach to simulate the EEJ has been through the analysis of EEJ magnetic e ects assuming simple current conÿgurations.…”