Spatial and temporal variations of small-scale plasma turbulence parameters in the equatorial electrojet: HF and VHF radar observational results

The spatial and temporal variations of various parameters associated with plasma wave turbulence in the equatorial electrojet (EEJ) at the magnetic equatorial location of Trivandrum (8.5 N, 77 E; dip 0.5 N) are studied for the first time, using co-located HF (18 MHz) and VHF (54.95 MHz) coherent backscatter radar observations (daytime) in the altitude region of 95–110 km, mostly on magnetically quiet days. The derived turbulence parameters are the mean electron density irregularity strength (δn/n), anomalous electron collision frequency (νe*) and the corrected east-west electron drift velocity (Vey). The validity of the derived parameters is confirmed using radar data at two different frequencies and comparing with in-situ measurements. The behaviour of δ n/n in relation to the backscattered power during weak and strong EEJ conditions is also examined to understand the growth and evolution of turbulence in the electrojet.