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To calculate the 13-month smoothed monthly mean sunspot number, which is commonly used to calculate the minima and maxima of solar cycles, a tapered-boxcar smoothing function is used. For a given month m {\displaystyle m} , with a monthly sunspot number of R m {\displaystyle R_{m}} , the smoothed monthly mean R s {\displaystyle R_{s}} can be ...
Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. [1]
Solar cycle 23 lasted 11.6 years, beginning in May 1996 and ending in January 2008. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 120.8 (March 2000), and the minimum was 1.7. [29] A total of 805 days had no sunspots during this cycle. [30] [31] [32]
English: The daily sunspot number from 1945-01-02 to 2017-06-30, and its power spectral analysis. There are two prominent peaks corresponding to its 27-day cycle and 11-year cycle. See "The 27-day signal in sunspot number series and the solar dynamo" (JL Le Mouël, MG Shnirman, EM Blanter - Solar Physics, 2007)
A prediction for Sunspot Cycle 24 (2008-2020) gives a smoothed sunspot number maximum of about 66 in the Summer of 2013. Current observations make this the smallest sunspot cycle since records began in the 1750s. [1] Solar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle.
Sunspot number is correlated with the intensity of solar radiation over the period since 1979, when satellite measurements became available. The variation caused by the sunspot cycle to solar output is on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W·m −2 compared with 1366 W·m −2 for the average solar constant).
Four solar flares occurred within 5 days from sunspot AR 12192, which is both the largest sunspot of solar cycle 24 and the largest since 1990. On October 19 there was a major X1.1-class solar flare. On October 22 an M8.7-class flare was followed by an X1.6 event.
Changes in carbon-14 concentration in the Earth's atmosphere, which serves as a long term proxy of solar activity.. This figure summarizes sunspot number observations. Since c. 1749, continuous monthly averages of sunspot activity have been available and are shown here as reported by the Solar Influences Data Analysis Center, World Data Center for the Sunspot Index, at the Royal Observatory of ...