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Titolo:
Does the poleward migration rate of the magnetic fields depend on the strength of the solar cycle?
Autore:
Makarov, VI; Tlatov, AG; Sivaraman, KR;
Indirizzi:
Pulkovo Observ, St Petersburg 196140, Russia Pulkovo Observ St Petersburg Russia 196140 St Petersburg 196140, Russia Indian Inst Astrophys, Bangalore 560034, Karnataka, India Indian Inst Astrophys Bangalore Karnataka India 560034 , Karnataka, India
Titolo Testata:
SOLAR PHYSICS
fascicolo: 1, volume: 202, anno: 2001,
pagine: 11 - 26
SICI:
0038-0938(2001)202:1<11:DTPMRO>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
MERIDIONAL FLOW; POLAR FIELDS; DIFFERENTIAL ROTATION; ACTIVE REGIONS; NEUTRAL LINE; SUN; FEATURES; PERIOD; PHOTOSPHERE; EVOLUTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Makarov, VI Pulkovo Observ, St Petersburg 196140, Russia Pulkovo Observ St Petersburg Russia 196140 rg 196140, Russia
Citazione:
V.I. Makarov et al., "Does the poleward migration rate of the magnetic fields depend on the strength of the solar cycle?", SOLAR PHYS, 202(1), 2001, pp. 11-26

Abstract

We present the pattern of the polar magnetic reversal for cycle 23 derivedfrom H alpha synoptic charts and have also included the reversals of the earlier cycles 18-22 for comparison. At the beginning of a new cycle (i.e., soon after the polar reversal) the zonal boundaries of unipolar magnetic regions of opposite polarities (seen as filament bands on the synoptic charts) appear close to and on either side of the equator continuing through the years of minimum indicating the onset of the cancellation of flux at these low latitudes. The cycle thus starts with cancellation of flux close to theequator and ends with the polar reversal or flux cancellation near the poles. The filament bands just below the polemost ones migrate and reach latitudes 35 degrees -45 degrees by the time of polar reversal and become the polemost, once the polar reversal has taken place. During the years of minimum that follow, these filament bands remain more or less stagnant at the latitudes 35 degrees -45 degrees except for occasional slow migration towards the equator. The migration to the poles starts at a low speed of 3 m s(-1) only when the spot activity has risen to a significant level and then it accelerates to 30 m s(-1) at the peak of the activity. It takes 3-4 years forthe polemost bands to reach the poles moving at these high speeds. We quantify this possible cause and effect phenomenon by introducing the concept of the 'strength of the solar cycle' and represent this by either of a set of three parameters. We show that the velocity of poleward migration is a linear function of the 'strength of the solar cycle'.

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Documento generato il 04/07/20 alle ore 15:06:12