Reconstruction of the Solar Activity in 1000–1700 Based on Auroral Data with Allowance for the Contribution of the Main Magnetic Field of the Earth

A new reconstruction of the number of sunspots (SN) in 1000–1700, along with possible errors, has been obtained based on an analysis of auroral observations at middle and low latitudes and data on the Earth's magnetic field at that time. The intensity and configuration of the main magnetic field of the Earth affect the penetration of the Earth's magnetosphere and atmosphere by aurora-induced, charged, solar-wind particles. Our reconstruction differs from other authors in that we have taken into account this effect on the frequency of auroras. The time variation of the reconstructed SN shows the previously known minima of Oort, Wolf, Spörer, and Maunder. The SN values for 1100–1150 (medieval maximum) are comparable to those observed in the second half of the XX century during the current period of high solar activity. It is shown that SN decreases by approximately two times during the Maunder minimum in comparison with the previous period, but it can reach SN ≈ 40 in some years. Bifurcation and degeneration of the 11-year cycle occurs at the beginning of the Maunder minimum. It can be associated with the difference in solar dynamo modes.