Estimating ionospheric currents using one plasma line and NHDS dispersion relation solver

Incoherent Scatter Radar (ISR) measurements provide an independent method to estimate ionospheric currents. We can estimate the ion and electron mean drift velocities from the ion and plasma line data respectively. These velocities together with the electron density can be used to calculate the ionospheric currents along the radar beam direction. Usually, the electron drift velocity is calculated from the Doppler offset between up- and downshifted plasma lines. Here, we propose an alternative method to estimate the electron drift velocity when only up- or downshifted plasma line data is available. We will assume that the electron drift is mainly due to the bulk motion of thermal electrons and use The New Hampshire Dispersion Relation Solver (NHDS) to get an estimate of the theoretical linear resonance frequency at an arbitrary angle to the magnetic field. We will use the ionospheric parameters estimated from the ion line as inputs to NHDS and as the output obtain the mean electron drift velocity. We will also compare the estimated ionospheric current with the one obtained using approximate analytical expression for the resonance frequency.