Beer et al. (2003) reconstructed the modulation potential on a multi-millennial timescale using the model computations by Masarik and Beer (1999) and the 10Be data from the GISP2 core in Greenland. This result has been extended, even including the 14C data set, and presently covers the whole Holocene (Vonmoos et al., 2006; Steinhilber et al., 2008).Update Usoskin et al. (2003c) presented the reconstruction of sunspot activity over the last millennium, based on 10Be data from both Greenland and Antarctica, using a physics-based model described in detail in Usoskin et al. (2004). This result reproduces the four known grand minima of solar activity – Maunder, Spörer, Wolf and Oort minima (see Section 4.3). Later Solanki et al. (2004) reconstructed 10-year–averaged sunspot numbers from the 14C content in tree rings throughout the Holocene and estimated its uncertainties (see Figure 15). This result was disputed by Muscheler et al. (2005), whose concurrent model, however, rested on an erroneous normalization, as argued in Solanki et al. (2005). The reconstruction of Solanki et al. (2004) has been recently updated by Usoskin et al. (2006a), using a newer paleomagnetic reconstruction by Korte and Constable (2005), and was later slightly revised (Usoskin et al., 2007), considering an updated model of the solar open magnetic flux by Krivova et al. (2007). Reconstruction of the HMF from 10Be data has been performed by Caballero-Lopez and Moraal (2004), using a model of CR modulation in the heliosphere and a 10Be production model by Webber and Higbie (2003). Recently it was revised (McCracken, 2007) to present a detailed reconstruction of HMF intensity since 1428.
The obtained results are discussed in Section 4.
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