Multi-spectral analysis of total solar irradiance variations
Abstract
A multi-variate spectral analysis is used to investigate the influence of sunspots by their area and classified according to their age and bright magnetic elements as shown by the full-disk equivalent width of the 1987 nm He-line on the total solar irradiance during 1980 and 1984/85. Most of the power in the spectrum of the SMM/ACRIM irradiance variance is explained by the effect of the complex sunspots groups showing new activity. The correlation with old sunspots is different and in general much lower. During the solar minimum, when only a few active regions are on the sun, the main contribution to the irradiance variations arises from the active network, which is formed by the breakup and dispersion of active regions. After eliminating the effect of sunspots and bright magnetic elements from the irradiance power spectrum, there are still peaks around 9 and 27 days, the strength of which seems to vary with solar activity. This indicates that other large scale effects produce irradiance variations, which may be modulated by same effect as produces solar activity.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1989
- Bibcode:
- 1989A&A...220..272F
- Keywords:
-
- Solar Activity Effects;
- Solar Radiation;
- Spectrum Analysis;
- Sunspot Cycle;
- Twenty-Seven Day Variation;
- Line Spectra;
- Solar Cycles;
- Solar Maximum Mission;
- Solar Physics