The synthesis of travelling ionospheric disturbance (TID) signatures in HPradar observations using ray tracing

Characteristic signatures are often observed in HF radar range-time-intensi ty plots when travelling ionospheric disturbances (TIDs) are present. These signatures, in particular the variation of the F-region skip distance, hav e been synthesised using a ray tracing model. The magnitude of the skip var iation is found to be a function of the peak electron density perturbation associated with the TID and radar frequency. Examination of experimental ob servations leads to an estimate of the peak electron density perturbation a mplitude of around 25% for those TIDs observed by the CUTLASS radar system. The advantage of using the skip variation over the radar return amplitude as an indicator of density perturbation is also discussed. An example of a dual radar frequency experiment has been given. The investigation of the ef fect of radar frequency on the observations will aid the optimisation of fu ture experiments.