Plasma drift motion in the F-region of the ionosphere using photometric nightglow measurements

Abstract

The equatorial ionospheric plasma irregularities have been studied in the last few years by different ground based (radar, digisonde, GPS, optical instruments) techniques and in situ rocket and satellite measurements. The time evolution and propagation characteristics of these irregularities have been used to study the important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. In this study the plasma drift motion has been inferred in zonal and meridional directions at Kolhapur (16.8°E, 74.2°E, dip latitude 10.6°N) by measuring the OI 630.0 nm intensities at three directions in zenith using tilting filter photometers. Also, the observed zonal plasma drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-93 model to investigate the thermosphere-ionosphere coupling. In general there is good agreement between the model predictions and the observations. The HWM-93 model also reproduces well the altitudinal and latitudinal variations of the neutral wind velocity in the low latitude region. The dominant periodicities observed in OI 630.0 nm intensity fluctuations on a Spread-F night were typically varying between 30 and 50 min.