On the Sun's General Magnetic Field

Cowling, T. G.

doi:10.1093/mnras/105.3.166

Cited by 174 publications

(88 citation statements)

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“…In fact, for starting the dynamo loop, flux transport dynamo models need a seed field at the tachocline-convective layer boundary. Also, a relic field appears to be essentially necessary for having the radiative interior rotating as a rigid body and evidences indicating that his field is pointing southward have been provided since Cowling (1945) suggested its existence (reviews in Mursula et al 2001, Duhau and. The persistence of a negative polar field component at the transition, as found here, gives further support to these findings.…”

Section: Pulsations?mentioning

confidence: 99%

A Remarkable Recent Transition in the Solar Dynamo

et al. 2016

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We summarize the major aspects of the remarkable, fairly long lasting period (∼ 2005 to ∼ 2010) of low solar activity, that we will call the Transition. It is the transitional stage between the Grand Maximum of the 20th century and a forthcoming (most probably Regular) episode of solar activity. The various kinds of activity in the functioning of the equatorial components of the solar dynamo before and during the Transition are summarized. While the behavior of unipolar magnetic regions and their rest-latitudes already gave very early indications -mid 20th century -of the forthcoming Transition, more such indications became available around 1995 and the main part of it occurred between 2005 and 2010. Some of the inferences are discussed. We submit the hypothesis that the solar tachocline undergoes pulsations and we present some helioseismic evidences. In that scenario we find that its equatorial part has moved downward over a fairly small semi-amplitude (∼ 0.03 solar radii) during the time of the Transition. There are several indications, apart from this 'pulsation', that the tachocline may even be pulsating with still smaller amplitudes in more modes. We speculate about the physical mechanism(s).

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Section: Pulsations?mentioning

confidence: 99%

A Remarkable Recent Transition in the Solar Dynamo

et al. 2016

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“…There have been attempts to extend the sunspot series back in time extrapolating the statistical properties of the WSN record (e.g., Nagovitsyn, 1997;De Meyer, 1998;Rigozo et al, 2001). Such models construct, e.g., a modulated carrier frequency or a multi-harmonic representation of the measured SN, which is then extrapolated backward in time.…”

Section: Indirect Solar Proxiesmentioning

confidence: 99%

“…This relates to the reversal of the global magnetic field of the Sun with the period of 22 years. It is often considered that the 11-year Schwabe cycle is the modulus of the sign-alternating Hale cycle (e.g., Sonett, 1983;Bracewell, 1986;Kurths and Ruzmaikin, 1990;De Meyer, 1998;Mininni, Gomez, and Mindlin, 2001). A hierarchy of sunspot cycles was presented, e.g., by Mordvinov and Kuklin (1999).…”

Section: Cyclicities In Solar Activitymentioning

confidence: 99%

“…Such an asymmetry can be naturally explained if one assumes a weak constant magnetic field in the bottom of the convection zone. A relic magnetic field can survive in the Sun due to the high conductivity in the solar interior (Cowling, 1945;Sonett, 1983). Some evidences favouring this idea have been presented earlier (Sonett, 1983;Bravo and Stewart, 1995;Boruta, 1996).…”

Section: -Year Cycle In Sunspot Activitymentioning

confidence: 99%

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Long-Term Solar Cycle Evolution: Review of Recent Developments

Usoskin¹,

Мурсула

2003

Solar Physics

153

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Abstract. The sunspot number series forms the longest directly observed index of solar activity and allows to trace its variations on the time scale of about 400 years since 1610. This time interval covers a wide range from seemingly vanishing sunspots during the Maunder minimum in 1645 -1700 to the very high activity during the last 50 years. Although the sunspot number series has been studied for more than a century, new interesting features have been found even recently. This paper gives a review of the recent achievements and findings in long-term evolution of solar activity cycles such as determinism and chaos in sunspot cyclicity, cycles during the Maunder minimum, a general behaviour of sunspot activity during a great minimum, the phase catastrophe and the lost cycle in the beginning of the Dalton minimum in 1790s and persistent 22-year cyclicity in sunspot activity. These findings shed new light on the underlying physical processes responsible for sunspot activity and allow a better understanding of such empirical rules as the Gnevyshev-Ohl rule and the Waldmeier relations.

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“…The ohmic decay timescale of a large-scale dipolar field embedded in the radiative interior is much larger than the estimated age of the Sun (Cowling 1945, Garaud 1999, so that a fraction of the magnetic flux initially frozen within the accreting protostellar gas is likely to persist today (Chapter 8). In parallel, according to the standard dynamo field theory, magnetic fields are thought to be constantly generated by fluid motions within the solar interior (Chapter 14).…”

Section: Magnetic Fields In the Tachoclinementioning

confidence: 99%

Magnetic confinement of the solar tachocline

Garaud¹

2007

The Solar Tachocline

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Two distinct classes of magnetic confinement models exist for the solar tachocline. The "slow tachocline" models are associated with a large-scale primordial field embedded in the radiative zone. The "fast tachocline" models are associated with an overlying dynamo field. I describe the results obtained in each case, their pros and cons, and compare them with existing solar observations. I conclude by discussing new lines of investigation that should be pursued, as well as some means by which these models could be unified or reconciled.

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On the Sun's General Magnetic Field

Cited by 174 publications

References 0 publications

A Remarkable Recent Transition in the Solar Dynamo

A Remarkable Recent Transition in the Solar Dynamo

Long-Term Solar Cycle Evolution: Review of Recent Developments

Magnetic confinement of the solar tachocline

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