scholarly journals The variations of solar magnetic networks over the solar cycle 23

2012 ◽  
Vol 8 (S294) ◽  
pp. 151-152
Author(s):  
Chong Huang ◽  
Yihua Yan ◽  
Yuanyong Deng ◽  
Yin Zhang ◽  
Baolin Tan ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Solar Cycle ◽  
Magnetic Activity ◽  
Watershed Algorithm ◽  
Heliospheric Observatory ◽  
Solar Cycle 23 ◽  
Solar Magnetic Activity ◽  
Doppler Interferometer

AbstractThis work analyzed the morphologic properties of magnetic networks during Carrington Rotations (CRs) 1955 to 2091 by applying the watershed algorithm to magnetograms observed by the Michelson Doppler Interferometer on board the Solar and Heliospheric Observatory spacecraft. We found that the magnetic networks are of fractal and the average fractal dimension is Df=1.253±0.011. We also find that both the fractal dimension and the size of magnetic networks are anti-correlated with the solar magnetic activity.

scholarly journals The future of helioseismology

2009 ◽  
Vol 5 (H15) ◽  
pp. 352-353
Author(s):  
Alexander G. Kosovichev
Keyword(s):  
Solar Cycle ◽  
Physical Properties ◽  
Active Regions ◽  
Magnetic Activity ◽  
Solar Dynamo ◽  
Current Status ◽  
The Sun ◽  
Interior Structure ◽  
Structure And Dynamics ◽  
Solar Magnetic Activity

AbstractHelioseismology has provided us with the unique knowledge of the interior structure and dynamics of the Sun, and the variations with the solar cycle. However, the basic mechanisms of solar magnetic activity, formation of sunspots and active regions are still unknown. Determining the physical properties of the solar dynamo, detecting emerging active regions and observing the subsurface dynamics of sunspots are among the most important and challenging problems. The current status and perspectives of helioseismology are briefly discussed.

scholarly journals What can the annual 10Be solar activity reconstructions tell us about historic space weather?

2018 ◽  
Vol 8 ◽  
pp. A23 ◽  
Author(s):  
Luke Barnard ◽  
Ken G. McCracken ◽  
Mat J. Owens ◽  
Mike Lockwood
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Solar Energetic Particle ◽  
Ground Level ◽  
Magnetic Activity ◽  
Cycle Phase ◽  
Large Space ◽  
Weather Events ◽  
Solar Magnetic Activity

Context: Cosmogenic isotopes provide useful estimates of past solar magnetic activity, constraining past space climate with reasonable uncertainty. Much less is known about past space weather conditions. Recent advances in the analysis of 10Be by McCracken & Beer (2015, Sol Phys 290: 305–3069) (MB15) suggest that annually resolved 10Be can be significantly affected by solar energetic particle (SEP) fluxes. This poses a problem, and presents an opportunity, as the accurate quantification of past solar magnetic activity requires the SEP effects to be determined and isolated, whilst doing so might provide a valuable record of past SEP fluxes. Aims: We compare the MB15 reconstruction of the heliospheric magnetic field (HMF), with two independent estimates of the HMF derived from sunspot records and geomagnetic variability. We aim to quantify the differences between the HMF reconstructions, and speculate on the origin of these differences. We test whether the differences between the reconstructions appear to depend on known significant space weather events. Methods: We analyse the distributions of the differences between the HMF reconstructions. We consider how the differences vary as a function of solar cycle phase, and, using a Kolmogorov-Smirnov test, we compare the distributions under the two conditions of whether or not large space weather events were known to have occurred. Results: We find that the MB15 reconstructions are generally marginally smaller in magnitude than the sunspot and geomagnetic HMF reconstructions. This bias varies as a function of solar cycle phase, and is largest in the declining phase of the solar cycle. We find that MB15's excision of the years with very large ground level enhancement (GLE) improves the agreement of the 10Be HMF estimate with the sunspot and geomagnetic reconstructions. We find no statistical evidence that GLEs, in general, affect the MB15 reconstruction, but this analysis is limited by having too few samples. We do find evidence that the MB15 reconstructions appear statistically different in years with great geomagnetic storms.

scholarly journals Deciphering Solar Magnetic Activity: 140 Years Of The ‘Extended Solar Cycle’ – Mapping the Hale Cycle

2021 ◽  
Author(s):  
Scott William McIntosh ◽  
Robert J Leamon ◽  
Ricky Egeland ◽  
Mausumi Dikpati ◽  
Richard C Altrock ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Magnetic Activity ◽  
Magnetic Cycle ◽  
Fundamental Feature ◽  
Superposed Epoch Analysis ◽  
Consistent Picture ◽  
Solar Magnetic Activity ◽  
Epoch Analysis ◽  
Observational Record ◽  
Sunspot Record

Abstract We investigate the occurrence of the ``extended solar cycle'' (ESC) as it occurs in a host observational data spanning 140 years. Investigating coronal, chromospheric, photospheric and interior diagnostics we develop a consistent picture of solar activity migration linked to the 22-year Hale (magnetic) cycle using superposed epoch analysis (SEA) using previously identified Hale cycle termination events as the key time for the SEA. Our analysis shows that the ESC and Hale cycle, as highlighted by the terminator-keyed SEA, is strongly recurrent throughout the entire observational record studied, some 140 years. Applying the same SEA method to the sunspot record confirms that Maunder's butterfly pattern is a subset of the underlying Hale cycle, strongly suggesting that the production of sunspots is not the fundamental feature of the Hale cycle, but the ESC is. The ESC (and Hale cycle) pattern highlights the importance of 55\degree\ latitude in the evolution, and possible production, of solar magnetism.

Latitudinal dependence of supergranular Area and Fractal dimension

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Paniveni Udayashankar
Keyword(s):  
Fractal Dimension ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Convection Zone ◽  
Magnetic Activity ◽  
The Sun ◽  
Physical Conditions ◽  
Quiet Region ◽  
Latitudinal Dependence ◽  
Shed Light

Abstract: A dependence of the area of supergranular cells with respect to the Latitude is studied and it is found that the cells are situated symmetrically about the ±250 latitude.Fractal dimension of the supergranular cells also shows a marginal latitudinal dependence, variation being in the range 1.6–1.7 in the latitudinal limits of ±300. Fractal dimension D for supergranulation is obtained according to the relation P ∝ AD/2 where ‘A is the area and ‘P’ is the perimeter of the supergranular cells. A difference in the fractal dimension between the active and quiet region cells is noted which is conjectured to be due to the magnetic activity level.Supergranular cells are essentially a manifestation of convective phenomena. They can shed light on the physical conditions in the convection zone of the Sun. Moreover, supergranules play a key role in the transport and dispersal of magnetic fields as it is an important step in our quest to understand the solar cycle.

scholarly journals Modelling solar cycle length based on Poincaré maps for Lorenz-type equations

2010 ◽  
Vol 28 (4) ◽  
pp. 993-1002 ◽  
Author(s):  
H. Lundstedt ◽  
T. Persson
Keyword(s):  
Dynamical Systems ◽  
Solar Cycle ◽  
Dynamic System ◽  
Cycle Length ◽  
Fractal Structure ◽  
Magnetic Activity ◽  
Long Tail ◽  
Solar Magnetic Activity ◽  
General Relations ◽  
Solar Cycle Length

Abstract. Two systems of Lorenz-type equations modelling solar magnetic activity are studied: Firstly a low order dynamic system in which the toroidal and poloidal fields are represented by x- and y-coordinates respectively, and the hydrodynamical information is given by the z coordinate. Secondly a complex generalization of the three ordinary differential equations studied by Lorenz. By studying the Poincaré map we give numerical evidence that the flow has an attractor with fractal structure. The period is defined as the time needed for a point on a hyperplane to return to the hyperplane again. The periods are distributed in an interval. For large values of the Dynamo number there is a long tail toward long periods and other interesting comet-like features. These general relations found for periods can further be physically interpreted with improved helioseismic estimates of the parameters used by the dynamical systems. Solar Dynamic Observatory is expected to offer such improved measurements.

CYCLE LENGTH DEPENDENCE OF STELLAR MAGNETIC ACTIVITY AND SOLAR CYCLE 23

2015 ◽  
Vol 802 (1) ◽  
pp. 67 ◽  
Author(s):  
Hwajin Choi ◽  
Jeongwoo Lee ◽  
Suyeon Oh ◽  
Bogyeong Kim ◽  
Hoonkyu Kim ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Cycle Length ◽  
Magnetic Activity ◽  
Length Dependence ◽  
Solar Cycle 23 ◽  
Stellar Magnetic Activity

scholarly journals An Estimation of Global p-mode Frequencies and Splittings from the IRIS Network Data: 1989–1996

2001 ◽  
Vol 203 ◽  
pp. 97-100 ◽  
Author(s):  
Sh. A. Ehgamberdiev ◽  
A. V. Serebryanskiy ◽  
Sh. S. Khalikov ◽  
E. Fossat ◽  
B. Gelly ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Activity Cycle ◽  
Data Bank ◽  
Magnetic Activity ◽  
Network Data ◽  
Frequency Table ◽  
Solar Magnetic Activity ◽  
Iris Data

The IRIS network has accumulated low-l p-modes data since July, 1989, i.e. one complete solar cycle. Since the last publication of a frequency table (Gelly et al. 1997) the IRIS data bank was not only filled with new data, but also has been supplemented with data from other helioseismology instruments, through cooperative programs. The results of a new estimations of frequencies and splitting obtained from IRIS++ data (Gelly et al. 1998) for period 1989-1996, as well as their variation along the solar magnetic activity cycle are presented.

scholarly journals Deciphering Solar Magnetic Activity: 140 Years of the ‘Extended Solar Cycle’ – Mapping the Hale Cycle

Solar Physics ◽  
2021 ◽  
Vol 296 (12) ◽  
Author(s):  
Scott W. McIntosh ◽  
Robert J. Leamon ◽  
Ricky Egeland ◽  
Mausumi Dikpati ◽  
Richard C. Altrock ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Magnetic Activity ◽  
Magnetic Cycle ◽  
Fundamental Feature ◽  
Superposed Epoch Analysis ◽  
Consistent Picture ◽  
Solar Magnetic Activity ◽  
Epoch Analysis ◽  
Observational Record ◽  
Sunspot Record

AbstractWe investigate the occurrence of the “extended solar cycle” (ESC) as it occurs in a host of observational data spanning 140 years. Investigating coronal, chromospheric, photospheric, and interior diagnostics, we develop a consistent picture of solar activity migration linked to the 22-year Hale (magnetic) cycle using superposed epoch analysis (SEA) and previously identified Hale cycle termination events as the key time for the SEA. Our analysis shows that the ESC and Hale cycle, as highlighted by the terminator-keyed SEA, is strongly recurrent throughout the entire observational record studied, some 140 years. Applying the same SEA method to the sunspot record confirms that Maunder’s butterfly pattern is a subset of the underlying Hale cycle, strongly suggesting that the production of sunspots is not the fundamental feature of the Hale cycle, but the ESC is. The ESC (and Hale cycle) pattern highlights the importance of $55^{\circ }$ 55 ∘ latitude in the evolution, and possible production, of solar magnetism.

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