SMOOTHED MONTHLY MEAN SUNSPOT NUMBERS =============================================================================== Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ------------------------------------------------------------------------------- 2014 77.3 78.3 80.8 81.9 80.5 79.7 78.5 75.5 70.8 67.3 65.4 2013 58.7 58.4 57.6 57.9 59.9 62.6 65.5 68.9 73.0 74.9 75.3 75.9 2012 65.5 66.9 66.8 64.6 61.7 58.9 57.8 58.2 58.1 58.6 59.7 59.6 2011 30.9 33.4 36.9 41.8 47.6 53.2 57.3 59.0 59.5 59.9 61.1 63.4 2010 9.3 10.6 12.3 14.0 15.5 16.4 16.7 17.4 19.6 23.2 26.5 28.8 2009 1.8 1.9 2.0 2.2 2.3 2.7 3.6 4.8 6.2 7.1 7.6 8.3 2008 4.2 3.6 3.3 3.4 3.5 3.3 2.8 2.7 2.3 1.8 1.7 1.7 2007 11.9 11.5 10.7 9.8 8.6 7.6 6.9 6.0 5.9 6.0 5.7 4.9 2006 20.8 18.6 17.4 17.1 17.3 16.3 15.2 15.6 15.5 14.2 12.6 12.1 2005 34.6 33.9 33.5 31.6 28.9 28.8 29.1 27.4 25.8 25.5 24.9 23.0 2004 52.0 49.3 47.1 45.5 43.8 41.6 40.2 39.2 37.5 35.9 35.3 35.2 2003 80.8 78.3 74.0 70.1 67.6 65.0 61.8 60.0 59.5 58.2 56.7 54.8 2002 113.5 114.6 113.3 110.5 108.8 106.2 102.7 98.7 94.6 90.5 85.2 82.0 2001 108.7 104.0 104.8 107.5 108.6 109.8 111.7 113.6 114.1 114.0 115.5 114.6 2000 112.9 116.8 119.9 120.8 119.0 118.7 119.8 118.6 116.3 114.5 112.7 112.0 1999 82.6 84.6 83.8 85.5 90.5 93.1 94.3 97.5 102.3 107.8 111.0 111.1 1998 43.7 48.9 53.4 56.5 59.4 62.5 65.5 67.8 69.5 70.5 73.0 77.9 1997 10.5 11.0 13.5 16.5 18.3 20.3 22.6 25.0 28.3 31.8 35.0 39.0 1996 10.4 10.1 9.7 8.5 8.0 8.5 8.4 8.3 8.4 8.8 9.8 10.4 Smoothed Sunspot Number Calculation ----------------------------------- The daily sunspot number has little, if any, relationship to ionospheric variability. However, the most widely used Ionospheric Index, R12, is derived from the daily sunspot numbers. The R12 index is a twelve-month smoothed relative sunspot number. To calculate the R12 index for July 2012 add half of the Jan 2012 value plus the sum of the Feb through Dec 2012 values plus half of the Jan 2013 value and by divide the sum twelve: Example Formula: [(n1/2)+(n2+n3+........n11+n12)+(n13/2)]/12 (where n1 = Jan 2012, n7 = July 2012 and n13 = Jan 2013) Full Data Link: ftp://ftp.ngdc.noaa.gov/STP/space-weather/solar-data/solar-indices/sunspot-numbers/ international/tables/table_international-sunspot-numbers_monthly-smoothed.txt