000004300 001__ 4300
000004300 005__ 20191114110630.0
000004300 0247_ $$2DOI$$a10.3847/1538-4357/ab4990
000004300 037__ $$aSCART-2019-0196
000004300 100__ $$aMathieu, Sophie
000004300 245__ $$aUncertainty Quantification in Sunspot Counts
000004300 260__ $$c2019
000004300 520__ $$aObserving and counting sunspots constitutes one of the longest-running scientific experiments, with first observations dating back to Galileo (around 1610). Today the sunspot number (SN) time series acts as a benchmark of solar activity in a large range of physical models. An appropriate statistical modeling, adapted to the time series' complex nature, is, however, still lacking. In this work, we provide the first comprehensive uncertainty quantification analysis of sunspot counts. We study three components: the number of sunspots (N s ), the number of sunspot groups (N g ), and the composite N c , defined as ${N}_{c}:= {N}_{s}+10{N}_{g}$. Those are reported by a network of observatories around the world and are corrupted by errors of various types. We use a multiplicative framework to provide, for these three components, an estimation of their error distribution in various regimes (short-term, long-term, minima of solar activity). We also propose a robust estimator for the underlying solar signal and fit density distributions that take into account intrinsic characteristics such as overdispersion, excess of zeros, and multiple modes. The estimation of the solar signal underlying the composite N c may be seen as a robust version of the International Sunspot Number (ISN), widely used as a proxy of solar activity. Therefore, our results on N c may help characterize the uncertainty on ISN as well. Our results pave the way for a future monitoring of the observatories in quasi-real time, with the aim of alerting the observers when they start deviating from the network and preventing large drifts from occurring.
000004300 536__ $$aBR/$$c165/$$fA3/VAL-U- SUN
000004300 594__ $$aSTCE
000004300 6531_ $$aSunspot
000004300 6531_ $$aStatistics
000004300 6531_ $$aSunspot counts
000004300 6531_ $$aUncertainties
000004300 700__ $$avon Sachs, Rainer
000004300 700__ $$aRitter, Christian 
000004300 700__ $$aDelouille, Véronique
000004300 700__ $$aLefèvre, Laure
000004300 773__ $$n1$$pThe Astrophysical Journal$$v886$$y2019
000004300 8560_ $$flaure.lefevre@observatoire.be
000004300 85642 $$ahttps://doi.org/10.3847/1538-4357/ab4990
000004300 85642 $$ahttps://iopscience.iop.org/article/10.3847/1538-4357/ab4990
000004300 8564_ $$s3664918$$uhttp://publi2-as.oma.be/record/4300/files/Mathieuetal2019.pdf
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000004300 905__ $$apublished in
000004300 980__ $$aREFERD