Sunspot areas and solar irradiance variations during 1980
Abstract
The realibility of daily measurements of sunspot areas made at the Space Environment Laboratories (SEL, Boulder, Colorado) is tested by comparison with measurements from other observatories, and they are found to be typically consistent to within 9 percent. The calculated visibility loss of sunspot due to poor seeing is no more than 13 percent of the projected sunspot areas. The resulting systematic error in derived solar constant values (S) will be less than 0.007 percent, although random measurement errors for sunspot areas can lead to corresponding random errors in the solar constant of as much as + or - 0.05 percent on 5 percnt of the days. The dominant contributor to short-term variations in S is the direct effect of sunspot blocking. A Goddard Space Flight Center interpretation of solar constant variations has used simulated sunspot areas that are systematically higher than the SEL measurements by 46 percent, which is well outside the expected range of measurement error or underestimation due to visibility losses.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1983
- DOI:
- 10.1086/161581
- Bibcode:
- 1983ApJ...275..878H
- Keywords:
-
- Periodic Variations;
- Solar Constant;
- Solar Flux Density;
- Sunspots;
- Error Analysis;
- Irradiance;
- Radiation Measurement;
- Tables (Data);
- Solar Physics