Short period fluctuations in the equatorial electrojet electric fields

Abstract

A study is made on the short period fluctuations in the equatorial electrojet parameters at the magnetic equatorial location of Trivandrum (8.5 ºN, 77 ºE; dip 0.5 ºN), during daytime for a number of magnetically quiet days, using coherent VHF backscatter radar observations in the altitude region of 90-115 km. For this study ΔH values at and off equatorial lati-tudes have also been used. The detailed analysis of radar and magnetometer data show the following: (a) Significant fluctua-tion amplitudes in the period range of 25-35 min are present in the radar observations at different range bins over and above the dominant diurnal pattern of the height invariant large scale E-W electric field (E_y). The same periods do manifest when the radar data products are divided into sub-intervals of 1-1.5 h. (b) Values of H also indicate the same periods as that of ra-dar observations. (c) A decrease in the amplitudes of the fluctuating components in H is seen from equator to low latitudes. The implications of the observations in terms of the possible origin of the fluctuations are discussed.