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2 Acta Geophysica

2 2007

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The IRI model residual difference and the new method of N(h)-profile determination

Maltseva O.A., Poltavsky O.S., Shlyupkin A.S.

Acta Geophysica

2007

Vol. 55, no. 3

441-458

The effectiveness of performance of the HF radio communication systems depends in many aspects on the accuracy of description of ionospheric conditions. One of possibilities of such a description is to use the IRI model. In the paper it is shown that discrepancies of the model N(h)-profile shape and the real shape can make a contribution to errors of description of ionospheric conditions by means of the IRI model. A residual difference (RD) remains even after adjusting the IRI model to the real-time parameters of foF2 and hmF2. These differences are esti-mated for the N(h)-profiles calculated from ionograms by the traditional method POLAN and the new method NeXtYZ. Estimates are given for the influence of these differences on the prediction accuracy of such parameters as the maximum usable frequency and the distance D between transmitters and receivers. An attempt was made to decrease the residual difference along the HF path by means of an analytical function approximating RD.

MOF/MUF behavior over one European path

Maltseva O.A., Barabashov B.G., Rodionova V.T., Shlyupkin A.S.

Acta Geophysica

2007

Vol. 55, no. 3

424-440

Many applications of HF propagation via the ionosphere (e.g. bearing-fingers, single station location, emergency systems and so on) demand an accurate description of ionospheric conditions. The International Reference Ionosphere (IRI) model is very often used for such a description. A lot of publications were devoted to the verification and improvement of this model. But most of them were based on data from vertical sounding (VS). Not so many comparisons with oblique sounding results have been reported. Specifically, this concerns parameters of the maximum usable frequency (MUF) and a ground range, D. In this paper errors of MUF and D determination by means of the IRI model are estimated on the example of the MOF data on Inskip–Rome path for December 2003. Adaptation of the model to current conditions by means of VS and total electron content TEC-GPS data is used to reduce these errors.