Problems in Forecasting of the Decennial Solar Activity in Terms of TSI by the Method of Analogs

Abstract

Reconstruction and forecasting the data series of total solar irradiation (TSI) is one of the most urgent scientific problems at the moment. In this paper, we review three reconstructions of TSI based on the data of cosmogenic ¹⁴C and ¹⁰Be isotopes and sunspots and tested their predictability by a modified analog method for a one-step prediction of decadal averages. The data of cosmogenic isotopes allow us to estimate changes of the open magnetic flux of the Sun, the magnitude of which is indirectly associated with TSI changes. We establish that the quality of the TSI forecast decreases if we consider a composite timeseries compiled from different data sources. In particular, the analog method does not work for reconstruction, various parts of which were recovered according to cosmogenic isotopes, the number of sunspots, and also according to modern satellite observations. However, at the same time, it operates for reconstructions recovered using cosmogenic isotopes for the whole series. Thus, the predictability of the series manifests the presence of a nonlinear deterministic component and is one of the criteria of the quality of reconstructions.