scholarly journals ANALYSIS ON CORRELATIONS BETWEEN SUBSURFACE KINETIC HELICITY AND PHOTOSPHERIC CURRENT HELICITY IN ACTIVE REGIONS

2012 ◽  
Vol 761 (1) ◽  
pp. L9 ◽  
Author(s):  
Yu Gao ◽  
Junwei Zhao ◽  
Hongqi Zhang
Keyword(s):  
Active Regions ◽  
Current Helicity

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

scholarly journals Intermittency spectra of current helicity in solar active regions

2018 ◽  
Vol 480 (3) ◽  
pp. 3780-3787 ◽  
Author(s):  
A S Kutsenko ◽  
V I Abramenko ◽  
K M Kuzanyan ◽  
Haiqing Xu ◽  
Hongqi Zhang
Keyword(s):  
Active Regions ◽  
Solar Active Regions ◽  
Current Helicity

scholarly journals A survey of flares and current helicity in active regions

1999 ◽  
Vol 139 (2) ◽  
pp. 311-320 ◽  
Author(s):  
S. D. Bao ◽  
H. Q. Zhang ◽  
G. X. Ai ◽  
M. Zhang
Keyword(s):  
Active Regions ◽  
Current Helicity

scholarly journals Current helicity and magnetic field anisotropy in solar active regions

2015 ◽  
Vol 454 (2) ◽  
pp. 1921-1930 ◽  
Author(s):  
H. Xu ◽  
R. Stepanov ◽  
K. Kuzanyan ◽  
D. Sokoloff ◽  
H. Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Regions ◽  
Solar Active Regions ◽  
Current Helicity

scholarly journals Statistical distribution of current helicity in solar active regions over the magnetic cycle

2013 ◽  
Vol 433 (2) ◽  
pp. 1648-1658 ◽  
Author(s):  
Y. Gao ◽  
T. Sakurai ◽  
H. Zhang ◽  
K. M. Kuzanyan ◽  
D. Sokoloff
Keyword(s):  
Active Regions ◽  
Statistical Distribution ◽  
Magnetic Cycle ◽  
Solar Active Regions ◽  
Current Helicity

Twist of Magnetic Fields in Solar Active Regions

2000 ◽  
Vol 179 ◽  
pp. 245-247
Author(s):  
Hongqi Zhang ◽  
Lirong Tian ◽  
Shudong Bao ◽  
Mei Zhang
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Northern Hemisphere ◽  
General Trend ◽  
Active Regions ◽  
Astronomical Observatory ◽  
Twisted Field ◽  
Current Helicity ◽  
Sunspot Groups

Extended abstractIn the solar atmosphere, the magnetic and current helicity have played an important role in the study of twisted magnetic field. Current helicity parameterh∥=B∥· (∇ ×B)∥and force free factorcan be used to analyze the distribution of twisted field (current helicity) in the photosphere (Seehafer 1990; Pevtsovet al.1995; Bao & Zhang 1998). Bao & Zhang (1998) and Zhang & Bao (1999) computed the photospheric current helicity parameterh∥for 422 active regions, including most of the large ones observed in the period of 1988–1997 at Huairou Solar Observing Station of Beijing Astronomical Observatory.The calculated results (Pevtsovet al.1995; Abramenkoet al.1996; Bao & Zhang 1998) show that most current helicities in sunspot groups in the northern hemisphere show negative sign in the northern hemisphere, while positive in the southern hemisphere, which is consistent with Seehafer’s result (Seehafer 1990). The distribution of current helicity parameterh∥in active regions also shows the butterfly pattern through the solar cycle. And, less than 30% of the active regions do not follow the general trend (Zhang & Bao 1998).

scholarly journals Current helicity constraints in solar dynamo models

2012 ◽  
Vol 8 (S294) ◽  
pp. 313-318
Author(s):  
D. Sokoloff ◽  
H. Zhang ◽  
D. Moss ◽  
N. Kleeorin ◽  
K. Kuzanyan ◽  
...  
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Mean Field ◽  
Active Regions ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Dynamo Model ◽  
Small Scale ◽  
Mean Field Dynamo ◽  
Current Helicity

AbstractWe investigate to what extent the current helicity distribution observed in solar active regions is compatible with solar dynamo models. We use an advanced 2D mean-field dynamo model with dynamo action largely concentrated near the bottom of the convective zone, and dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic 2D mean-field dynamo model with simple algebraic alpha quenching only. Using these numerical models we obtain butterfly diagrams for both the small-scale current helicity and the large-scale magnetic helicity, and compare them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by −A·B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are respectively the dynamo generated mean magnetic field and its vector potential.

Analysis of electric current helicity in active regions on the basis of vector magnetograms

Solar Physics ◽  
1996 ◽  
Vol 168 (1) ◽  
pp. 75-89 ◽  
Author(s):  
V. I. Abramenko ◽  
Tongjiang Wang ◽  
V. B. Yurchishin
Keyword(s):  
Electric Current ◽  
Active Regions ◽  
Vector Magnetograms ◽  
Current Helicity
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