ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/maxmin.new MINIMA AND MAXIMA OF SUNSPOT NUMBER CYCLES =============================================================================== Sunspot Year Smallest Year Largest Rise Fall Cycle Cycle of Smoothed of Smoothed to Max to Min Length Number Min* Monthly Mean** Max* Monthly Mean** (Yrs) (Yrs) (Yrs) ------------------------------------------------------------------------------- - 1610.8 -- 1615.5 -- 4.7 3.5 8.2 - 1619.0 -- 1626.0 -- 7.0 8.0 15.0 - 1634.0 -- 1639.5 -- 5.5 5.5 11.0 - 1645.0 -- 1649.0 -- 4.0 6.0 10.0 - 1655.0 -- 1660.0 -- 5.0 6.0 11.0 - 1666.0 -- 1675.0 -- 9.0 4.5 13.5 - 1679.5 -- 1685.0 -- 5.5 4.5 10.0 - 1689.5 -- 1693.0 -- 3.5 5.0 8.5 - 1698.0 -- 1705.5 -- 7.5 6.5 14.0 - 1712.0 -- 1718.2 -- 6.2 5.3 11.5 - 1723.5 -- 1727.5 -- 4.0 6.5 10.5 - 1734.0 -- 1738.7 -- 4.7 6.3 11.0 - 1745.0 -- 1750.3 92.6 5.3 4.9 10.2 1 1755.2 8.4 1761.5 86.5 6.3 5.0 11.3 2 1766.5 11.2 1769.7 115.8 3.2 5.8 9.0 3 1775.5 7.2 1778.4 158.5 2.9 6.3 9.2 4 1784.7 9.5 1788.1 141.2 3.4 10.2 13.6 5 1798.3 3.2 1805.2 49.2 6.9 5.4 12.3 6 1810.6 0.0 1816.4 48.7 5.8 6.9 12.7 7 1823.3 0.1 1829.9 71.7 6.6 4.0 10.6 8 1833.9 7.3 1837.2 146.9 3.3 6.3 9.6 9 1843.5 10.5 1848.1 131.6 4.6 7.9 12.5 10 1856.0 3.2 1860.1 97.9 4.1 7.1 11.2 11 1867.2 5.2 1870.6 140.5 3.4 8.3 11.7 12 1878.9 2.2 1883.9 74.6 5.0 5.7 10.7 13 1889.6 5.0 1894.1 87.9 4.5 7.6 12.1 14 1901.7 2.6 1907.0 64.2 5.3 6.6 11.9 15 1913.6 1.5 1917.6 105.4 4.0 6.0 10.0 16 1923.6 5.6 1928.4 78.1 4.8 5.4 10.2 17 1933.8 3.4 1937.4 119.2 3.6 6.8 10.4 18 1944.2 7.7 1947.5 151.8 3.3 6.8 10.1 19 1954.3 3.4 1957.9 201.3 3.6 7.0 10.6 20 1964.9 9.6 1968.9 110.6 4.0 7.6 11.6 21 1976.5 12.2 1979.9 164.5 3.4 6.9 10.3 22 1986.8 12.3 1989.6 158.5 2.8 6.8 9.7 23 1996.4*** 8.0 2000.3*** 120.8 4.0 ------------------------------------------------------------------------------- Mean Cycle Values: 6.1 113.2 4.7 6.3 11.0 ------------------------------------------------------------------------------- *When observations permit, a date selected as either a cycle minimum or maxi- mum is based in part on an average of the times extremes are reached in the monthly mean sunspot number, in the smoothed monthly mean sunspot number, and in the monthly mean number of spot groups alone. Two more measures are used at time of sunspot minimum: the number of spotless days and the frequency of occurrence of "old" and "new" cycle spot groups. **The smoothed monthly mean sunspot number is defined here as the arithmetic average of two sequential 12-month running means of monthly mean numbers. ***May 1996 marks the mathematical minimum of Cycle 23. October 1996 marks the consensus minimum determined by an international group of solar physicists. April 2000 marks the mathematical maximum of Cycle 23. However, several other solar indices (e.g., 10.7 cm solar radio flux) recorded a higher secondary maximum in late 2001.