Relationships between relative sunspot numbers and air temperature

Abstract

Monthly means of relative sunspot numbers (1749-1991) and temperature anomalies of the two hemispheres (1851-1987 for the northern and 1858-1987 for the southern hemisphere) have been analysed by means of spectral methods. All series contain signals of an approximately 11-year period cycle. Amplitudes and lengths of this cycle are time dependent. Therefore, stationary approaches often fail. The appropriately filtered curves of sunspot cycle frequency and long-term evolution of air temperature show a high correspondence in wide time intervals. Thus, the varying sun cycle period turns out to be a good indicator for the long-term temperature history on Earth (at least for the investigated period). This result is similar to that of Friis-Christensen and Lassen (1991) obtained with other methods of analysis (for the northern hemisphere).

Keywords

• relative sunspot numbers
• sunspot cycle
• northern hemisphere
• sonnenfleckenrelativzahlen
• sonnenfleckenzyklus
• nordhemisphäre