SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 14 - JULY 18, 2006
92 SOLAR PHYSICS
Includes solar activity, solar flares, solar radiation and sunspots.
For related information see 93 Space Radiation.
20060020186 NASA Marshall Space Flight Center, Huntsville, AL, USA
On the Relation Between Sunspot Area and Sunspot Number
Wilson, Robert M.; Hathaway, David H.; February 2006; 24 pp.; In English; Original contains black and white illustrations Report No.(s): NASA/TP-2006-214324; M-1158; No Copyright; Avail.: CASI: A03, Hardcopy
Often, the relation between monthly or yearly averages of total sunspot area, A, and sunspot number, R, has been described using the formula A = 16.7 R. Such a simple relation, however, is erroneous. The yearly ratio of A/R has varied between 5.3 in 1964 to 19.7 in 1926, having a mean of 13.1 with a standard deviation of 3.5. For 1875-1976 (corresponding to the Royal Greenwich Observatory timeframe), the yearly ratio of A/R has a mean of 14.1 with a standard deviation of 3.2, and it is found to differ significantly from the mean for 1977-2004 (corresponding to the USAAir Force/National Oceanic and Atmospheric Administration Solar Optical Observing Network timeframe), which equals 9.8 with a standard deviation of 2.1. Scatterplots of yearly values of A versus R are highly correlated for both timeframes and they suggest that a value of R = 100 implies A=1,538 +/- 174 during the first timeframe, but only A=1,076 +/- 123 for the second timeframe. Comparison of the yearly ratios adjusted for same day coverage against yearly ratios using Rome Observatory measures for the interval 1958-1998 indicates that sunspot areas during the second timeframe are inherently too low. Author
Sunspots; Solar Cycles; Standard Deviation; Predictions
Source: NASA
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