Open AccessFirst observational evidence for opposite zonal electric fields in equatorial E and F region altitudes during a geomagnetic storm period
Author(s) -
Tulasi Ram S.,
Balan N.,
Veenadhari B.,
Gurubaran S.,
Ravindran S.,
Tsugawa T.,
Liu H.,
Niranjan K.,
Nagatsuma T.
Publication year - 2012
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2012ja018045
Subject(s) - equatorial electrojet , ionosphere , electrojet , geology , electric field , geophysics , daytime , longitude , f region , geomagnetic storm , earth's magnetic field , anomaly (physics) , atmospheric sciences , latitude , geodesy , physics , magnetic field , quantum mechanics , condensed matter physics
The strong westward electrojet and simultaneous upward drift of the equatorial ionospheric peak observed over South‐East Asia and Indian equatorial regions during the prolonged Dst minimum phase of an intense geomagnetic storm during 14–15 December 2006 are investigated for the altitudinal variation of zonal electric field polarity using ground based and space‐borne observations. The results show first observational evidence for simultaneous existence of daytime westward and eastward zonal electric fields at equatorial E and F region altitudes, respectively, in a wide longitude sector. While the westward electric fields at E region altitudes cause westward electrojet, at the same time, the eastward zonal electric fields at F region altitudes cause the upward drift of the equatorial ionospheric peak and reinforcement of the equatorial ionization anomaly (EIA) even in the topside ionosphere (∼660 km). The reversal of the electric fields is found to occur at ∼280 km height. A clear bifurcation of F region plasma at ∼280 km is evident in the iso‐electron density contours due to these oppositely polarized zonal electric fields, which manifests as an unusually deep cusp between F 1 and F 2 layers on equatorial ionograms.