East-Siberian Center for the Earth's Ionosphere Research (SDC ESCEIR)

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Mathematical modelling and information support subdivision

Maximum usable frequencies on-line prediction

The on-line prediction procedure is based on the Newton interpolation formulae for a uniform distribution of the variable with first, second and third argument powers restrictions (Kurkin V.I. , Polekh N.M., Tchistyakova L.V. MAF operative prognosis for oblique ionosphere sounding// Issledovaniya po geomagnrtismu, aeronomii i phisike Solntsa. - SB RAS publishing, issue. 105., 1997). Interpolating polynomial coefficients are derived by finite differences calculated for a current model extrapolation interval and for past time interval experimental data.

On the basis of this algorithm we develop a computational scheme for real-time on-line prediction, which can perform sequentially the following operations:

• Experimental data processing and accumulation for three sounding runs;
• Experimental MAF three-point smoothing;
• MUF calculation by long-run prognosis model for last run time and for the next 15-minute interval;
• MUF changing for prognosis interval by long-run prognosis model;
• Prediction MUF calculation for the next 15 minutes;
• MUF prediction value output.

These calculations have shown that the linear approximation of the on-line prediction has the best precision when using long-run prediction values independent of the interval and ionospheric disturbance level.

In the figure we present MUF daily variations for different days, for quiet and disturbed geomagnetic conditions.