A Study On The Technique Of Reconstructing The Ionosphere From Vertical Sounding Data FoF₂

The ionosphere is a time-variable, dispersive, anisotropic and asymmetrical medium. The research of it especially of the F2-layer is very important not only to the short-wave communication and sounding, but also to the electronic countermeasures. This paper emphasizes on reconstructing ionosphere and wants to speculate on thesequential Real-time distribution of F2-layer's critical frequency foF2 in limitregions by making use of the parameters from nine observation stations on mainland China.This paper provides a method which makes use of the Artifical Neural Netwok(ANN) to reconstruct the ionospheric foF2's sequential Real-time distribution inlimit regions, expatiates the process which establishes the ionosphere model by ANN, discusses the influences of the stations' distribution, validates the result by the data that have never been used overseas, and concludes that the root-mean-square (rms) is within 0.7MHz.In this paper the author improves the kriging technique to reconsrtuct the ionosphere. Considering the linear relation between 12-month smoothed relativesunspot number R₁₂ and critical frequency foF2, using International ReferenceIonosphere model (IRI) as the background ionosphere, the author also puts forwards the improved method and process, meanwhile, analyzes some data in the solar activity high year and the solar activity low year, gives examples at four representative times,then obtains the contours of critical frequency foF2 . The contours which isreconstructed by the improved kriging technique is more smooth .The root-mean-square (rms) of the 88.44% examples of the solar activity high year is within 1MHz, and also is the 85.15% examples of the solar activity low year. Under the two kinds of solar activity circumstances, the root-mean-square (rms) of the four representative time is within 0.73MHz. It is indicated that the improved kriging technique is the best method.Then kriging method, the invert distance method, region attenuation multiplier method and update IRI method are compared. The methods are validated by using the same-time-data from the observation stations out of the mainland of China. It is concluded that the improved kriging reconstructing method using the linear relation between Ru and critical frequency foF2, region attenuation multiplier method and update IRI method are all effectual. And it is valuable using the IRI as background ionosphere in reconstruction ionosphere.