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Hathaway, David H.; Wilson, Robert M.; Reichmann, E. J.

doi:10.1023/a:1022425402664

Cited by 222 publications

(117 citation statements)

References 16 publications

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“…A similar relationship has been found between cycle periods and cycle amplitudes as seen in the longer record of sunspot numbers (Hathaway, Wilson, & Reichmann 1999Solanki et al 2002). Wang et al (2002) recently found that variations in the (surface) meridional flow are needed in their flux transport models to maintain stable magnetic polarity oscillations (although in their simulations the noted correlation is between current cycle surface flow speed and cycle amplitude).…”

Section: Discussionsupporting

confidence: 69%

Evidence That a Deep Meridional Flow Sets the Sunspot Cycle Period

Hathaway

Nandy

Wilson

et al. 2003

ApJ

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149

119

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Sunspots appear on the Sun in two bands on either side of the equator that drift toward lower latitudes as each sunspot cycle progresses. We examine the drift of the centroid of the sunspot area toward the equator in each hemisphere from 1874 to 2002 and find that the drift rate slows as the centroid approaches the equator. We compare the drift rate at sunspot cycle maximum with the period of each cycle for each hemisphere and find a highly significant anticorrelation: hemispheres with faster drift rates have shorter periods. These observations are consistent with a meridional counterflow deep within the Sun as the primary driver of the migration toward the equator and the period associated with the sunspot cycle. We also find that the drift rate at maximum is significantly correlated with the amplitude of the following cycle, a prediction of dynamo models that employ a deep meridional flow toward the equator. Our results indicate an amplitude of about 1.2 m s À1 for the meridional flow velocity at the base of the solar convection zone.

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Section: Discussionsupporting

confidence: 69%

Evidence That a Deep Meridional Flow Sets the Sunspot Cycle Period

Hathaway

Nandy

Wilson

et al. 2003

ApJ

Self Cite

149

119

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“…All of these indicators show cyclic behavior from days to hundreds of years (Krivova & Solanki 2002;Braun et al 2005;Atac et al 2006;Kilcik et al 2010). Due to their particularly long temporal extension (∼400 years), the ISSN and SSA are the most used solar activity indicators, many of them are strongly correlated with each other (Hathaway et al 2002). The length of the solar cycle varies between 7.4 and 14.8 years and often depends on the method of determination (Usoskin & Mursula 2003).…”

Section: Introductionmentioning

confidence: 99%

Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles

Kılçık

Yurchyshyn

Abramenko

et al. 2011

ApJ

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Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification), and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.

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“…This can provide information about the activity level of an ensuing cycle. The positive correlation between R m and R min is a well-known fact (Hathaway et al 2002). As a natural consequence, the very low level of solar activity at the present time (around the onset of Cycle 24) seems to be followed by a very weak (Svalgaard et al 2005;Schatten 2005), or even the weakest cycle (Li 2009).…”

Section: Introductionmentioning

confidence: 64%

Does a low solar cycle minimum hint at a weak upcoming cycle?

Du¹,

Wang²

2010

Res. Astron. Astrophys.

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The maximum amplitude (R m ) of a solar cycle, in the term of mean sunspot numbers, is well-known to be positively correlated with the preceding minimum (R min ). So far as the long term trend is concerned, a low level of R min tends to be followed by a weak R m , and vice versa. In this paper, we found that the evidence is insufficient to infer a very weak Cycle 24 from the very low R min in the preceding cycle. This is concluded by analyzing the correlation in the temporal variations of parameters for two successive cycles.

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Untitled

Cited by 222 publications

References 16 publications

Evidence That a Deep Meridional Flow Sets the Sunspot Cycle Period

Evidence That a Deep Meridional Flow Sets the Sunspot Cycle Period

Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles

Does a low solar cycle minimum hint at a weak upcoming cycle?

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