The North–South Asymmetry of Soft X-RAY Flare Index During Solar Cycles 21, 22 and 23

Joshi, Bhuwan; Joshi, Anand D.

doi:10.1023/b:sola.0000022977.95023.a7

Cited by 80 publications

(29 citation statements)

References 34 publications

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“…In 1997, 1999 and 2000, when the cycle was in ascending phase, northern hemisphere dominated. The preference for northern hemisphere during the rising and maximum phase of cycle 23 is reported by Ataç andÖzgüç (2001) and Joshi and Joshi (2004) (2001) we find that the variations in N-S asymmetry index during cycle 23 differ from cycle 22 but are similar to cycle 21. There was mostly a southern dominance during cycle 22 while cycle 21 showed northern dominance during the early phases and southern dominance during the later phases.…”

Section: Latitudinal Distribution and N-s Asymmetrysupporting

confidence: 77%

“…There is a strong southern dominance during the solar cycle minima in 1996. This behavior of asymmetry that it peaks at or around the minimum phase of solar activity has been reported in several studies with different manifestations of solar activity (Swinson, Koyama, and Saito 1986;Vizoso and Ballester 1990;Joshi and Joshi 2004). In 1997, 1999 and 2000, when the cycle was in ascending phase, northern hemisphere dominated.…”

Section: Latitudinal Distribution and N-s Asymmetrysupporting

confidence: 76%

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North-south distribution of solar flares during cycle 23

2006

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In this paper, we investigate the spatial distribution of solar flares in the northern and southern hemisphere of the Sun that occurred during the period 1996 to 2003. This period of investigation includes the ascending phase, the maximum and part of descending phase of solar cycle 23. It is revealed that the flare activity during this cycle is low compared to previous solar cycle, indicating the violation of Gnevyshev-Ohl rule. The distribution of flares with respect to heliographic latitudes shows a significant asymmetry between northern and southern hemisphere which is maximum during the minimum phase of the solar cycle. The present study indicates that the activity dominates the northern hemisphere in general during the rising phase of the cycle (1997)(1998)(1999)(2000). The dominance of northern hemisphere is shifted towards the southern hemisphere after the solar maximum in 2000 and remained there in the successive years. Although the annual variations in the asymmetry time series during cycle 23 are quite different from cycle 22, they are comparable to cycle 21.

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Section: Latitudinal Distribution and N-s Asymmetrysupporting

confidence: 77%

Section: Latitudinal Distribution and N-s Asymmetrysupporting

confidence: 76%

North-south distribution of solar flares during cycle 23

2006

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“…For certain solar cycles there may be evidence that the N-S asymmetry evolves with the solar cycle, whereas in general this is not the case. By studying the north-south asymmetry of soft X-ray flare index in cycles 21-23, Joshi & Joshi (2004) found that there exists a real north-south asymmetry in solar flare activity which is not due to random fluctuations, and the hemispheric asymmetry is strengthened during solar minimum. They also found that the hemispheric asymmetry of soft X-ray flare index has a periodic behavior shifted in phase with respect to the solar cycle, and the significant periods of daily asymmetry time series are around 28.26 days, 550.73 days and 3.72 years.…”

Section: Introductionmentioning

confidence: 99%

Statistical properties of solar Hα flare activity

Deng

Xiao-juan

et al. 2017

J. Space Weather Space Clim.

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-Magnetic field structures on the solar atmosphere are not symmetric distribution in the northern and southern hemispheres, which is an important aspect of quasi-cyclical evolution of magnetic activity indicators that are related to solar dynamo theories. Three standard analysis techniques are applied to analyze the hemispheric coupling (north-south asymmetry and phase asynchrony) of monthly averaged values of solar Ha flare activity over the past 49 years (from 1966 January to 2014 December). The prominent results are as follows: (1) from a global point of view, solar Ha flare activity on both hemispheres are strongly correlated with each other, but the northern hemisphere precedes the southern one with a phase shift of 7 months; (2) the long-range persistence indeed exists in solar Ha flare activity, but the dynamical complexities in the two hemispheres are not identical; (3) the prominent periodicities of Ha flare activity are 17 years full-disk activity cycle and 11 years Schwabe solar cycle, but the short-and mid-term periodicities cannot determined by monthly time series; (4) by comparing the non-parametric rescaling behavior on a point-by-point basis, the hemispheric asynchrony of solar Ha flare activity are estimated to be ranging from several months to tens of months with an average value of 8.7 months. The analysis results could promote our knowledge on the long-range persistence, the quasi-periodic variation, and the hemispheric asynchrony of solar Ha flare activity on both hemispheres, and possibly provide valuable information for the hemispheric interrelation of solar magnetic activity.

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“…However, it is well known that there are many differences between northern and southern hemispheres in individual cycles. There has been much interest for many years in describing and understanding such differences (Verma, 1993;Oliver and Ballester, 1994) for solar flares (Garcia, 1990;Joshi and Joshi, 2004), the solar wind (Mursula and Zieger, 2001;Bzowski et al, 2003), long-lived solar filaments (Duchlev, 2001), solar and heliospheric magnetic fields (Bravo and Gonzáles-Esparza, 2000), cosmic-ray propagation (Simpson, Zhang, and Bame, 1996), and geomagnetic activity (Murayama and Nosaka, 1991).…”

Section: Introductionmentioning

confidence: 99%

Simulating Solar Cycles in Northern and Southern Hemispheres by Assimilating Magnetic Data into a Calibrated Flux-Transport Dynamo

et al. 2007

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We use the flux-transport dynamo prediction scheme introduced by Dikpati, de Toma, and Gilman (Geophys. Res. Lett. 33, L05102, 2006) to make separate simulations and predictions of sunspot cycle peaks for northern and southern hemispheres. Despite the division of the data, the skill level achieved is only slightly lower than that achieved for the sum of both hemispheres. The model shows skill at simulating and predicting the difference in peaks between North and South, provided that difference is more than a few percent. The simulation and prediction skill is achieved without adjustment to any parameters of the model that were used when peaks for the sum of North and South sunspot areas was simulated. The results are also very insensitive to the averaging length applied to the input data, provided the simulations and predictions are for peaks defined by averaging the observations over at least 13 rotations. However, in its present form, the model is not capable of skillfully simulating or predicting short-time-scale features of individual solar cycles.

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The North–South Asymmetry of Soft X-RAY Flare Index During Solar Cycles 21, 22 and 23

Cited by 80 publications

References 34 publications

North-south distribution of solar flares during cycle 23

North-south distribution of solar flares during cycle 23

Statistical properties of solar Hα flare activity

Simulating Solar Cycles in Northern and Southern Hemispheres by Assimilating Magnetic Data into a Calibrated Flux-Transport Dynamo

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