Preferred sunspot longitudes: non-axisymmetry  and differential rotation

Usoskin, Ilya; Berdyugina, S. V.; Poutanen, Juri

doi:10.1051/0004-6361:20053201

Cited by 57 publications

(109 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By filtering the data with this limit, 53% of the CRs shows exactly one significant longitudinal belt; meanwhile, the remaining fraction of the data did not show strong in-homogeneous properties. Many studies have adressed the existence of the co-dominant longitude that has a phase shift of 180°from the dominant peak (Usoskin et al 2005;Zhang et al 2007Zhang et al , 2011a. However, we have found that the secondary AL is not, or is hardly detectable, after applying a high-pass filter to sort out the insignificant peaks.…”

Section: The Methods Of Tracking Almentioning

confidence: 62%

“…DISCUSSION AND CONCLUSION Zhang et al (2008) found that the ALs with half widths of 20°-30°contain 80% of C-flares during the solar minimum and X-flares during solar maximum. The AL was defined by the dynamic reference frame, introduced by Usoskin et al (2005). Hence, their study assumes two detectable and equally strong ALs, separated by 180°.…”

Section: Temporal Properties Of Solar Flares Near Almentioning

confidence: 99%

See 1 more Smart Citation

Active Longitude and Solar Flare Occurrences

Gyenge

Ludmány

Baranyi

2016

ApJ

View full text Add to dashboard Cite

The aim of the present work is to specify the spatio-temporal characteristics of flare activity observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Geostationary Operational Environmental Satellite (GOES) in connection with the behavior of the longitudinal domain of enhanced sunspot activity known as active longitude (AL). By using our method developed for this purpose, we identified the AL in every Carrington Rotation provided by the Debrecen Photoheliographic Data. The spatial probability of flare occurrence has been estimated depending on the longitudinal distance from AL in the northern and southern hemispheres separately. We have found that more than 60% of the RHESSI and GOES flares is located within 36   from the AL. Hence, the most flare-productive active regions tend to be located in or close to the active longitudinal belt. This observed feature may allow for the prediction of the geo-effective position of the domain of enhanced flaring probability. Furthermore, we studied the temporal properties of flare occurrence near the AL and several significant fluctuations were found. More precisely, the results of the method are the following fluctuations: 0.8, 1.3, and 1.8 years. These temporal and spatial properties of the solar flare occurrence within the active longitudinal belts could provide us with an enhanced solar flare forecasting opportunity.

show abstract

Section: The Methods Of Tracking Almentioning

confidence: 62%

Section: Temporal Properties Of Solar Flares Near Almentioning

confidence: 99%

Active Longitude and Solar Flare Occurrences

Gyenge

Ludmány

Baranyi

2016

ApJ

View full text Add to dashboard Cite

show abstract

“…Follow-up studies concerning the preferred locations (longitudes) of sunspot formation delivered inconsistent and partly contradictory results. Even today, the possible number, migration, life times, longterm behavior and the particular method to track them remain a subject of debate (see Berdyugina and Usoskin 2003;Usoskin et al 2005;Pelt et al 2006;Usoskin et al 2007;Weber et al 2013;Gyenge et al 2014). …”

Section: Cyclic Changes Of the Coronal Magnetic Fieldmentioning

confidence: 99%

The magnetic field in the solar atmosphere

Wiegelmann

Thalmann

Solanki

2014

Astron Astrophys Rev

176

125

View full text Add to dashboard Cite

This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quiet Sun and coronal holes.

show abstract

“…-aggregated data (daily Wolf numbers) and correlation analysis (Bogart 1982); -raw heliographic longitudes and longitude-wise binning (Trotter & Billings 1962;Warwick 1965); -transformed (using trial rotation velocity) longitudes and χ 2 statistic (Bai 1987); -transformed (using latitude-dependent rotation velocities) longitudes and pattern matching (Usoskin et al 2005;Pelt et al 2006, hereafter PBKT); -spherical harmonic decomposition and time series analysis of mode amplitudes, phases and phase-walks (Juckett 2003).…”

Section: Introductionmentioning

confidence: 99%

Solar active regions: a nonparametric statistical analysis

Pelt

Korpi

Tuominen

2010

A&A

View full text Add to dashboard Cite

Context. The sunspots and other solar activity indicators tend to cluster on the surface of the Sun. These clusters very often occur at certain longitudes that persist in time. It is of general interest to find new and simple ways to characterize the observed distributions of different indicators and their behaviour in time. Aims. In the present work we use Greenwich sunspot data to evaluate the statistical but not totally coherent stability of the sunspot distribution along latitudes as well as longitudes. The aim was to obtain information on the longitudinal distribution of the underlying spot-generating mechanism rather than on the distribution and migration of sunspots or sunspot groups on the solar surface. Therefore only sunspot groups were included in the analysis, and only the time of their first appearance was used. Methods. We used a simple nonparametric approach to reveal sunspot migration patterns and their persistency. Results. Our analysis shows that regions where spots are generated tend to rotate differentially as the spots and spot groups themselves do. The spatial correlations in activity, however, tend to break down relatively fast, during 7-15 solar rotations. Conclusions. This study provides a challenge for solar dynamo models, as our results indicate that the non-axisymmetric spotgenerating mechanism experiences differential rotation (known as phase mixing in dynamo theory). The new nonparametric method introduced here, completely independent of the choice of the longitudinal distribution of sunspots, was found to be a useful tool for spatio-temporal analysis of surface features.

show abstract

Preferred sunspot longitudes: non-axisymmetry and differential rotation

Cited by 57 publications

References 12 publications

Active Longitude and Solar Flare Occurrences

Active Longitude and Solar Flare Occurrences

The magnetic field in the solar atmosphere

Solar active regions: a nonparametric statistical analysis

Contact Info

Product

Resources

About