Studies of The EEJ From Satellite and Ground Magnetic Data
The EEJ phenomenon was first identified using geomagnetic data. The amplitude of the daily variation of the horizontal magnetic intensity (ΔH) measured at a geomagnetic observatory near the dip-equator is 3–5 fold higher than the variation of data from other regions of Earth. A typical diurnal equatorial observatory data show a peak of strength ~80 nT at 12:00 LT, with respect to the night-time level. Egedal (1947) showed that the enhancement of quiet day solar daily variations in ΔH (Sq(H)) lay within the 50 latitude centered on the dip equator. The mechanism that produced the variation in the magnetic field was proposed as a band of current about 300 km in width flowing over the dip equator.
EEJ studies from satellite data were initiated with the arrival of data from the POGO (Polar Orbiting Geophysical Observatories) series of satellite (1967–1970). The characteristic signature of the EEJ is a sharp negative V-shaped curve in the H field, attaining its minimum within 0.5° of the magnetic dip equator. The magnetic data from satellite missions like Ørsted (1999–present) and CHAMP (2000–present) have vastly improved our knowledge of the EEJ.
Read more about this topic: Equatorial Electrojet
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