A short-term periodicity near 155 day in sunspot areas
Abstract
Evidence is presented of a nearby 155-day periodicity in the historical record of sunspot areas from 1904 to 1976, rotation by rotation, covering cycles 14 to 20. This suggests that earlier periodicities around 155 days found in other indicators of solar activity during the last three cycles could be connected to the one presented here. Due to the fact that the amount of emerging magnetic flux is directly proportional to sunspot areas, this result also suggests the existence of a periodicity in the emergence of magnetic flux through the solar photosphere. Another peak of about 510-540 days, pointed out in solar flares by several authors, is also present in these results; however, it is not significant at all, because it remains below the level of the 'null continuum'.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1990
- Bibcode:
- 1990A&A...238..377C
- Keywords:
-
- Magnetic Flux;
- Photosphere;
- Solar Activity;
- Solar Flares;
- Sunspot Cycle;
- Sunspots;
- Fast Fourier Transformations;
- Harmonics;
- Power Spectra;
- Solar Rotation;
- Time Series Analysis;
- Solar Physics