Application of the HF Doppler observations in studying spread-F

Abstract

In this paper,the applications of the HF Doppler shift observations in the study on ionospheric spread-F are demonstrated with observational cases.These cases show that,the HF Doppler shift observation is continuous so that the evolution process of the ionospheric spread-F can be clearly understood in the view of observation.The HF Doppler frequency shifts are so sensitive to the scattering of the echoes caused by ionospheric irregularities,to the various scale of traveling ionospheric disturbances(TIDs),and to sudden frequency deviation(SFD) caused by solar flare that it has good advantage to investigate the physics mechanism of spread-F and the correlation between the spread-F and the ionospheric background disturbances according to the time series of the ionospheric disturbances in the observational records.The HF Doppler shift can observe the different time scale of the spread-F(from less than 1 hour to more than several hours) completely.It will be avoided to lose in the time series in record the spread-F occurrence and can decide the precision start and end time of the spread-F.Beside the obvious advantage,the HF Doppler also has some limitations in the observation,such as the spatial resolution.With comprehensive observation and data analysis,it is helpful for studying the physical mechanisms of the spread-F and for forecasting the ionospheric disturbances.