Solar surface rotation: N-S asymmetry and recent speed-up

Zhang, L.; Мурсула, К.; Usoskin, Ilya

doi:10.1051/0004-6361/201425169

Cited by 20 publications

(14 citation statements)

References 37 publications

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“…The study has supported southern activity dominated predictions of Verma (1992) and Li et al (2009a) for the current cycle. Zhang et al (2015) studied N-S asymmetry of X-ray flares of class B and higher, during solar cycle 24. They found that the asymmetry was fairly constant and negative (i.e., SH dominant) and SH rotates faster than the NH.…”

Section: Resultsmentioning

confidence: 99%

“…The solar N-S asymmetry is considered as one of the most interesting properties of solar activity and studied in many manifestations of solar activity such as flares, prominences, sunspots, filaments, etc. (Howard 1974;Roy 1977;Yadav et al 1980;Swinson et al 1986;Ballester 1987, 1990;Carbonell et al 1993;Oliver and Ballester 1994;Joshi 1995;Javaraiah and Gokhale 1997;Verma 2000;Ataç and Özgüç 2001;Temmer et al 2002;Joshi and Joshi 2004;Ballester et al 2005;Javaraiah and Ulrich 2006;Zaatri et al 2006;Temmer et al 2006;Carbonell et al 2007;Li et al 2009a,b;Gigolashvili et al 2011;Chowdhury et al 2013;Chandra et al 2013;Obridko et al 2014;Joshi et al 2015;Zhang et al 2015;Javaraiah 2016;Bruevich and Yakunina 2017;Deng et al 2017;Gurgenashvili et al 2017;Xie et al 2018;El-Borie et al 2019;Li et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

Joshi¹,

Chandra

2020

Open Astronomy

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Here we present the results of the study of the north-south (N-S) distribution and asymmetry of GOES soft X-ray (SXR) flares during solar cycle 24. The period of study includes ascending, maximum and descending phases of the cycle. During the cycle double-peaked (2011, 2014) solar maximum has occurred. The cycle peak in the year 2011 is due to B-class flares excess activity in the northern hemisphere (NH) whereas C and M class flares excess activity in the southern hemisphere (SH) supported the second peak of the cycle in 2014. The data analysis shows that the SXR flares are more pronounced in 11 to 20 degree latitudes for each hemisphere. Cumulative values of SXR flare count show northern excess during the ascending phase of the cycle. However, in the descending phase of the cycle, southern excess occurred. In the cycle a significant SH dominated asymmetry exists. Near the maximum of the cycle, the asymmetry enhances pronouncedly and reverses in sign.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

Joshi¹,

Chandra

2020

Open Astronomy

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“…Bai (1987Bai ( , 1988 analysed the coordinates of energetic solar flares based of 5 years of time period and concluded that longitudinal spatial distribution is non-homogeneous. Zhang et al (2007Zhang et al ( , 2008Zhang et al ( , 2015 concluded that the dominant and co-dominant AL contains 80% of C-and X-flares. In GY16, we conducted a similar study based on four solar cycles and we did not find significant co-dominant activity; instead, we found that only the dominant AL contains 60% of the solar flares.…”

Section: Solar Non-axisymmetric Activitymentioning

confidence: 99%

Active Longitude and Coronal Mass Ejection Occurrences

Gyenge

Singh

Kiss

et al. 2017

ApJ

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The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (AL). In order to reveal the connection between the AL and CME spatial occurrences, here we investigate the morphological properties of active regions. The first morphological property studied is the separateness parameter, which is able to characterise the probability of the occurrence of an energetic event, such as solar flare or CME. The second morphological property is the sunspot tilt angle. The tilt angle of sunspot groups allows us to estimate the helicity of active regions. The increased helicity leads to a more complex built-up of the magnetic structure and also can cause CME eruption. We found that the most complex active regions appear near to the AL and the AL itself is associated with the most tilted active regions. Therefore, the number of CME occurrences is higher within the AL. The origin of the fast CMEs is also found to be associated with this region. We concluded that the source of the most probably CME-capable active regions is at the AL. By applying this method we can potentially forecast a flare and/or CME source several Carrington rotations in advance. This finding also provides new information for solar dynamo modelling.

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“…Here, the spectral bands are centered at the power peaks above the red-noise level of the global wavelet spectrum. Zhang et al (2015) applied a differentially rotating reference system to determine the bestfit annual values of the differential rotation parameters of active longitudes of solar X-ray flares and sunspots in 1977-2012, and found that the rotation of both hemispheres has been speeding up at roughly the same rate since the late 1990s, with the southern hemisphere rotating slightly faster than the northern hemisphere. Joshi et al (2015) investigated the temporal evolution and north-south asymmetry in the occurrence of soft X-ray flare index during solar cycles 21-23.…”

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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Solar surface rotation: N-S asymmetry and recent speed-up

Cited by 20 publications

References 37 publications

North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

Active Longitude and Coronal Mass Ejection Occurrences

Statistical properties of solar Hα flare activity

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