ABSTRACT We explore the links between averaged sunspot numbers (SSN) and a modulus summary curve (MSC) of two largest eigenvectors solar background magnetic field (SBMF) derived from principal component analysis. MSC has rather close correspondence with whole set SSN revealing cycle timings, duration, maxima times for cycles 12–24, 6, 7, −4, −3, while few in mid-18th mid-19th centuries there ar...