Extended solar-activity cycle

Technical Report · Thu Jun 23 04:00:00 EDT 1988

OSTI ID:5707900

Wilson, P R; Altrock, R C; Harvey, K L; Martin, S F; Snodgrass, H B

The solar cycle has been defined in terms of a sequential periodic variation in sunspot numbers, the period being the interval between successive minima, currently averaging 11.2 years. But a number of observations have indicated that the activity cycle may begin at higher latitudes before the emergence of the first sunspots of the new cycle. Here results are reported from sunspot cycle 21 concerning the ephemeral active regions, the coronal green-line emission and the torsional oscillation signal, which confirm the earlier suggestions. The appearance of a high-latitude population of ephemeral active regions in the declining phases of sunspot cycle 21, is reported with orientations that tend to favor those for cycle 22 rather than 21. Taken together, these data indicate that sunspot activity is simply the main phase of a more-extended cycle that begins at high latitudes before the maximum of a given sunspot cycle and progresses towards the equator during the next 18-22 yr, merging with the conventional 'butterfly diagram' (the plot of the latitudes of emerging sunspots against time) as it enters sunspot latitudes. This extended cycle may be understood in the perspective of a model of giant convective rolls that generate dynamo waves propagating from pole to equator.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5707900
• Report Number(s): AD-A-205324/7/XAB; AFGL-TR-89-0047
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
EMISSION SPECTRA
MAPPING
OSCILLATIONS
SIGNALS
SOLAR ACTIVITY
SOLAR CORONA
SOLAR CYCLE
SPECTRA
STARSPOTS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
SUNSPOTS
VARIATIONS
WAVE PROPAGATION