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Forecast scheme for a Dst index based on Fourier extrapolation.

Presentation #211.10 in the session Planetary Space Physics (Poster)

Published onOct 23, 2023
Forecast scheme for a Dst index based on Fourier extrapolation.

Romashets, Vandas, and Majumder (2023) demonstrated that the function Ap(t) can be approximated by a sum of sin and cos with periods T, T/2, T/3,.., T/Nmax where T = 27 days and the maximum number of harmonics used being Nmax=108. Dst index is available hourly, which means that Nmax is 324. In our analysis, we use the data from 27 days preceding the moment at which the forecast should be issued. The coefficients, an and bn, near sin and cos functions are determined by the method of orthogonality. The measure of success is the root mean square of the difference between actual and predicted values of the planetary index Dst in the next three days. We tested the approach on data from 2006-2023 and found that the percentage error is within the range of 15-20 %. The number of harmonics N is the free parameter, which can be adjusted, depending on level of geomagnetic activity. This research was supported by NSF grant 2230363. M. V. acknowledges support from the AV CR grant RVO:67985815 and GACR grant 21-26463S.

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