Accurate and Robust Sensing of the Ionosphere With Uncoded Long Pulse ISR Measurements: 2. Differential Drift Inversions Using Lag Profile Phase Data

Abstract A method of estimating heavy (O + ) and light (H + and He + ) ion drift velocities in the topside F‐region ionosphere using Arecibo uncoded long pulse data is presented. We show that multi‐ion drift velocity estimation using long pulse ACF phase data requires accurate knowledge of ionospheric state parameters, such as temperatures and compositions, that can be independently estimated using power spectral fitting techniques. We describe a three‐stage fitting procedure utilizing spectral and ACF phase models to mitigate the range ambiguity effects caused by long pulse transmissions. The procedure provides comprehensive ionospheric state parameter estimates including drift velocities of different ionic species. Results of ion drift measurements over a 63‐hr interval in September 2016 are presented. The results, covering 200–1,000 km altitude range with 5‐min time and 6 km range resolution, exhibit events of substantial counter‐streaming of the heavy and light ions during post‐sunset and pre‐sunrise periods.