LONG-TERM TRENDS IN SUNSPOT MAGNETIC FIELDS

Abstract

Recent studies indicate that a maximum field strength in sunspots shows a gradual decrease over the last several years. By extrapolating this trend, Penn & Livingston proposed that sunspots may completely disappear in the not-so-distant future. To verify these recent findings, we employ historic synoptic data sets from seven observatories in the former USSR covering the period from 1957 to 2011 (from 1998 to 2011, observations were taken at only one observatory). Our results indicate that while sunspot field strengths rise and wane with solar cycle, there is not a long-term trend that would suggest a gradual decrease in sunspot magnetic fields over the four and a half solar cycles covered by these observations.