The Rise and Fall of Open Solar Flux During the Current Grand Solar Maximum

Lockwood, Mike; Rouillard, A. P.; Finch, I.

doi:10.1088/0004-637x/700/2/937

Cited by 146 publications

(242 citation statements)

References 27 publications

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“…As this data has been taken during a grand solar maximum (Lockwood, Rouillard, and Finch, 2009) it is not necessarily the case that the conclusions will have been true in the less active times prior to the grand maximum. To test this, the open solar flux and near-Earth magnetic field reconstructed from geomagnetic activity data have been used, employing the sunspot number variations to define the start/end times of the polarity cycle.…”

Section: Discussionmentioning

confidence: 99%

“…We use these data sets to examine the behaviour of the heliospheric magnetic field over six additional, pre-space age polarity cycles. This enables us to test whether this difference in heliospheric parameters during qA>0 and qA<0 polarity cycles is limited to the space-age, which spans the recent grand solar maximum (Solanki et al, 2004;Lockwood, Rouillard, and Finch, 2009;Lockwood et al, 2012), or whether it is a more persistent feature. Geomagnetic reconstruction of the heliospheric field is limited to yearly values because annual variations in factors such as the ionospheric conductivity and Earths dipole tilt influence the coupling between the solar wind and the geomagnetic field.…”

Section: Geomagnetic Reconstructions Of the Pre-space Age Heliospherementioning

confidence: 99%

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The 22-Year Hale Cycle in Cosmic Ray Flux – Evidence for Direct Heliospheric Modulation

2013

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The ability to predict times of greater galactic cosmic ray (GCR) fluxes is important for reducing the hazards caused by these particles to satellite communications, aviation, or astronauts. The 11-year solar cycle variation in cosmic rays is highly correlated with the strength of the heliospheric magnetic field. Differences in GCR flux during alternate solar cycles yield a 22-year cycle, known as the Hale Cycle, which is thought to be due to different particle drift patterns when the northern solar pole has predominantly positive (denoted a qA>0 cycle) or negative (qA<0) polarities. This results in the onset of the peak cosmic ray flux at Earth occurring earlier during qA>0 cycles than for qA<0 cycles and hence the peak being more domed for qA>0 and more sharply peaked for qA<0. In this study, we demonstrate that properties of the large-scale heliospheric magnetic field are different during the declining phase of the qA<0 and qA>0 solar cycles, when the difference in GCR flux is most apparent. This suggests that particle drifts may not be the sole mechanism responsible for the Hale Cycle in GCR flux at Earth. However, it is also demonstrated that these polarity-dependent heliospheric differences are evident during the space-age but much less clear in earlier data: using geomagnetic reconstructions, it is shown that for the period of 1905 -1965, alternate polarities do not give as significant a difference during the declining phase of the solar cycle. Thus we suggest that the 22-year cycle in cosmic ray flux is at least partly the result of direct modulation by the heliospheric magnetic field and that this effect may be primarily limited to the grand solar maximum of the space-age.

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Section: Discussionmentioning

confidence: 99%

Section: Geomagnetic Reconstructions Of the Pre-space Age Heliospherementioning

confidence: 99%

The 22-Year Hale Cycle in Cosmic Ray Flux – Evidence for Direct Heliospheric Modulation

2013

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“…Usoskin et al (2014), who studied solar activity over a period of three millennia, confirmed this subdivision. The reality of the recent (20th century) Grand Maximum is confirmed in critical studies by Solanki et al (2004), Lockwood et al (2009Lockwood et al ( , 2010, Lockwood (2012) and Clette et al (2014), although, after the introduction of the new system of sunspot counting (Clette et al 2014;Svalgaard and Schatten 2016), the maximum is less extreme than was thought before. Clette et al (2014) call it the 'Modern Maximum'.…”

Section: Introductionmentioning

confidence: 88%

“…The Grand Maximum started in 1924 (Duhau and Chen 2002;) while Lockwood et al (2009) place the beginning in 1920. For the end of it find 2008 (cf.…”

Section: Introductionmentioning

confidence: 99%

“…For the end of it find 2008 (cf. our Table 1 later in this paper, and the corresponding text), while Lockwood et al (2009) The period that we are discussing here is the time interval between the past Grand Maximum and a forthcoming Episode of which and de Jager and Duhau (2012) give arguments that it will be of the Regular type. In this paper we will call this transitional period the Transition.…”

Section: Introductionmentioning

confidence: 99%

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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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Variation of the solar magnetic flux spectrum during solar cycle 23

Jin

Wang

2014

JGR Space Physics

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[1] By using the unique database of Solar and Heliospheric Observatory/Michelson Doppler Imager full disk magnetograms from September 1996 to January 2011, covering the entire solar cycle 23, we analyze the time-variability of the solar magnetic flux spectrum and study the properties of extended minimum of cycle 23. We totally identify 11.5 million magnetic structures. It has been revealed that magnetic features with different magnetic fluxes exhibit different cycle behaviors. The magnetic features with flux larger than 4.0 10 19 Mx, which cover solar active regions and strong network features, show exactly the same variation as sunspots; however, the remaining 82% magnetic features which cover the majority of network elements show anti-phase variation with sunspots. We select a criterion that the monthly sunspot number is less than 20 to represent the Sun's low activity status. Then we find the extended minimum of cycle 23 is characterized by the long duration of low activity status, but the magnitude of magnetic flux in this period is not lower than previous cycle. Both the duration of low activity status and the minimum activity level defined by minimum sunspot number show a century period approximately. The extended minimum of cycle 23 shows similarities with solar cycle 11, which preceded the mini-maxima in later solar cycles. This similarity is suggestive that the solar cycles following cycle 23 are likely to have low activity.

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The Rise and Fall of Open Solar Flux During the Current Grand Solar Maximum

Cited by 146 publications

References 27 publications

The 22-Year Hale Cycle in Cosmic Ray Flux – Evidence for Direct Heliospheric Modulation

The 22-Year Hale Cycle in Cosmic Ray Flux – Evidence for Direct Heliospheric Modulation

A Remarkable Recent Transition in the Solar Dynamo

Variation of the solar magnetic flux spectrum during solar cycle 23

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