Probing of the artificial hole in the ionosphere with the HF skywave radar

This paper explains the experiment in which HF skywave radar probed the artificial ionospheric hole, which is caused by the flames of the rocket vertically launched and penetrated the ionosphere. After the rocket had passed through the ionosphere, the minimum time-delay P/sub min/-f on the backscatter ionograms obviously appeared with wave and focusing stripes resulting from the irregular structure etc. The results indicated that there was a low electron density zone, the artificially created hole in the ionosphere along the propagation path. Under the asymmetry quasi-cosine ionospheric hole model, the experimental P/sub min/-f was simulated with the technique of ray tracing. It was deduced that the range size of the hole in the ionosphere along the radar beams was some 573 km and the critical frequency of the center was 2.6 MHz lower than the background critical frequency (12 MHz). The ionospheric environment 350 km away from the launching site was disturbed and the propagation velocity of the ionospheric disturbance was about 50 m/s.