Fast Detection And Analysis Of Meso-micro Scale Ionospheric Disturbances

Ionospheric disturbance detection and diagnosis has been an important research subject in the ionosphere physics.The continuous development of detection systems and experimental analysis methods can extracte more reliable parameters to reflect the the ionospheric disturbance forms and change characteristics.Measuring the Doppler frequency shift and inversing the normal velocity of electron concentration isosurface of ionospheric echos is an impotant way to study ionospheric disturbances.We work arround this direction and the multi-frequency detection system-PDI platform,which is jointly developed by Chinese Academy of Science and South-Central University for Nationalities,is introduced in the paper.Fast detection and analysis of meso-micro scale ionospheric disturbances has been realized on this platform.The newly developed PDI platform consists of antennas,transmitter,receiver and PC data receiving and processing system.It is portable for mobile observation and temporary array detection.The ionogram minimum detection period is less than 1 minute and the Doppler frequency shift resolution up to 0.039 Hz.It also has strong anti-interference ability and good ionogram observation effect.The parameters can be set flexibly to develop various detection modes and researches such as ionospheric transient changes,etc.On PDI platform,this paper proposes a time-interleaved frequency sweep detection mode,which solves the contradiction between Doppler resolution and detection time in conventional Doppler shift measurement.It can be guarranteed that we will acquire high-resolution Doppler shift at the same time greatly shorten the detection period,in order to realize rapid detection of disturbances.We collect a long-time raw data of the ionosphere based on this new detection method and platform in Wuhan observatory.Through the way to acquire high-precision Doppler frequency shift and the method to inverse the normal velocity of electron concentration isosurface,we obtain the Doppler ionograms and vertical disturbance velocity of O waves.Furthermore,we deduce the real-time changes of ionospheric disturbances with time and space.By wavelet analyses and correloperiodogram analyses on these time domain signals,We extract the relatively accurate disturbance scale and analyze the disturbance excitation sources of each time segment.Preliminary results show that these disturbances are mainly mesoscale TIDs motivated by Polar activities which often appear in winter in central China.This paper also compares the three commonly used inversion methods : equivalent mirror reflection,considering the influence of geomagnetic field and neglecting the influence of geomagnetic field.The results show that the accuracy of the inversion results is the highest when the geomagnetic field is considered,and the ionospheric disturbances have almost the same change trends which is achieved by the three kinds of inversion methods.It indicates that the observation data and the research methods are reliable and stable.At last,this paper discusses the mathematical model and parameter extraction method of non-single ionospheric disturbance field.The 2D profiles changing with time and true height of the disturbance parameters are also presented,which provides an important basis for observing large scale ionospheric disturbances and researching atmospheric meridional wind field.In a word,this paper introduces a new ionospheric radio frequency detection system,and focuses on the discussion of the meso-micro scale ionospheric disturbance information extraction methods.We verify the feasibility of design scheme through a lot of experiments,which provides an effective means for observing and researching the multi-frequency and multi-point propagation characteristics of ionospheric disturbances.