Evolution of the 155 day periodicity in sunspot areas during solar cycles 12 to 21

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169378· OSTI ID:6163875

Lean, J ^[1]

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1. E. O. Hulburt Center for Space Research, Washington, DC (USA)

Sunspot area data during solar cycles 12-21 are examined with both periodogram and evolutionary spectral analysis techniques for evidence of a periodicity near 155 days. This periodicity is found to be present only during epochs of maxium activity, when it modulates the sunspot areas by as much as 15-20 percent of the amplitude of the 11 yr cycle. The 155 day periodicity typically occurs in episodes of from 1 to 3 yr, with sequential episodes often in opposite solar hemispheres; the strengths of these episodes appear to track the general level of solar activity. Comparing the phases of sinusoids fitted to the sunspot area data within individual solar cycles provides evidence for coherency within + or - 8 days of a period at 155 days between solar cycles 19, 20, and 21. However, within any one episode the actual period of the 155 day cycle may drift from 130 to 185 days. 31 refs.

• OSTI ID: 6163875
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 363; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
COMPARATIVE EVALUATIONS
MATHEMATICS
SOLAR ACTIVITY
SOLAR CYCLE
SOLAR FLARES
STARSPOTS
STELLAR ACTIVITY
SUNSPOTS
TIME-SERIES ANALYSIS