Simulation of equatorial electron density profiles and their corresponding vertical incidence ionograms

by Quirino Sugon Jr.

I am writing an end of project report which I must send tomorrow.  I need some related literature on the simulation of equatorial electron density profiles and their corresponding vertical incidence ionograms.  Here’s what I found from the web:

M. A. Cervera and T. J. Harris, Modelling the eff ects of ionospheric disturbances on quasi-vertically incident ionograms using 3D magneto-ionic raytracing, URSIGASS 2011. This is by DSTO Australia. I need to talk to them regarding their ionosonde at Manila Observatory. The authors use quasiparabolic (QP) method just like others. Our method is via cosine splines.  They use Hamiltonian ray tracing, which makes the ray paths dependent on the gradient of the refractive index.  But this method will only work for oblique incidence and not for vertical incidence.  That is why the authors clarified that the method is actually quasi-vertical incidence.

Ionospheric Physics Program, Report on the U.S. Program for the International Geophysical Year, by National Academy of Sciences–National Research Council (Washington DC, November 1965), pp. 253-314.  In p. 257 it was mentioned that there were plans to place vertical ionosphere in equatorial countries: Western Pacific, Marianas Islands, Line Islands in East Central Pacific, and South America.  It was mentioned in p. 276 that they use the matrix method of Budden to extract the electron density as a function of true height, using the group refractive index expressed as a matrix.  The true height is computed using matrix inversion. The assumption is monotonic variation of the electron density as a function of height (p. 277).  This is the assumption that we wish to avoid.

L.A. McKinnell and A.W.V. Poole, Efforts to produce realistic ionograms from electron density profiles in the F1 region, URSI Proceedings, General Assembly 2002, p 0017.   They are using neural networks.  But they did not show an actual ionogram.

Carlo Scotto, Electron density profile calculation technique for Autoscala ionogram analysis, Advances in Space Research
Volume 44, Issue 6, 15 September 2009, Pages 756-766. I cannot access the article yet.

Reinisch, B., and H. Xueqin (1983), Automatic calculation of electron density profiles from digital ionograms 3. Processing of bottomside ionograms, Radio Sci., 18(3), 477-492. Parabolic profile shapes are assumed for the E region and the valley between the E and the F layer. The F layer is approximated by a single sum of Chebyshev polynomials, and the entire profile is described by a set of 16 numerical values.

Xuequin Huang, Uncertainty boundaries of electron density profiles deduced from ionograms, University of Massachusetts Lowell, Center for Atmospheric Research (UML-CAR), XI International Digisonde Forum, 30 April to 3 May 2007. The author is using Chebyshev polynomials for the electron density as a function of real height. The presentation mentions spread (range and frequency). I think this is similar to what we are getting, but I am not sure if this refers to the simulation or to the actual data. Construction of the boundary lines requires matrix inversion. Is this the technique of Budden? Ok, he is not using our method.  He is still trying to invert the ionogram to obtain the electron density profile.

The International Satellite for Ionospheric Studies (ISIS) is digitizing its ionograms in the 1960s and 1970s.  There is a TOPIST software for inverting these ionograms for the topside ionosphere.

Xueqin Huang and Bodo Reinisch, Vertical electron density profiles from digisonde ionograms: the average representative profile,  Annali de Geofisica, 39(4), 1996. Similar to that of Xuequin Huang in the previous paper.



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