Auroral electrojet oval

Abstract

The auroral electrojet is enhanced in the polar ionosphere associated with charged particle precipitation and fieldaligned currents during substorms. In this paper the geometry of the elctrojet is determined by using the ionospheric equivalent current systems for every 5 minutes during March 18 and 19, 1978. The latitudinal and local time shifts of the oval are examined. Possible relationship of the electrojet oval with expansion of the auroral oval and the fieldaligned current belts during substorms are discussed. The electrojet oval in the polar region consists of westward and eastward electrojets, varying with AE index. As the magnetic activity increases, the westward electrojet has distinct latitudinal shifts in different local time sectors: it shifts poleward around the midnight (23:00-03:00 MLT), while moves equatorward in the morning sector (03:00-10:00 MLT) and afternoon sector (20:00-23:00 MLT. The eastward electrojet includes two insulated parts: a higher-latitude part around 80• latitude in the nighttime sector (21:00-03:00 MLT) and a lower-latitude part between 60• -70• latitudes in other local time sectors. As AE index increases, the higher-latitude part of the eastward electrojet expands eastward from 03:00 to 08:00 MLT, while the lower-latitude part shows a equatorward shift in the afternoon sector, which is more or less similar to the westward electrojet.

Large‐amplitude GPS TEC variations associated with Pc5–6 magnetic field variations observed on the ground and at geosynchronous orbit

“…In addition, the Iqaluit magnetometer ( Figure 1) observed a decrease in the downward magnetic field (not shown), suggesting that the electrojet current was centered somewhere between Sanikiluaq and Iqaluit. Chen et al [2003] predicted an enhanced eastward current, centered at about 70°magnetic latitude in the post noon sector, for similar levels of auroral activity. Beginning around 17:20 UTC, coincident with appearance of Pc5-6 activity in GOES 13 measurements, significant Pc5-6 variations of up to 50 nT appeared in mainly the eastward (y) and downward (z) magnetic field in Sanikiluaq.…”

Uncertainty in magnetic activity indices

“…During the substorm expansion phase, the auroral electrojets shifted poleward or/and equatorward [7][8][9][10] . In some strong substorms, the electrojet moved beyond the AE-station belt.…”

Analysis of auroral electrojet magnetic indices

“…The AuroralElectrojet is an enhanced electric current in the polar ionosphere associated with charged particle precipitation and field aligned currents during substorms (Chen et al, 2003). A substorm sometimes referred to as a magnetosphericsubstorm or an Auroralsubstorm is a brief disturbance in the Earth's magnetosphere that causes energy to be released from the 'tail' of the magnetosphere and injected into the high latitude ionosphere.…”