scholarly journals Helicity of solar magnetic field from observations

2009 ◽  
Vol 5 (S264) ◽  
pp. 181-190
Author(s):  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Solar Magnetic Field ◽  
Interplanetary Space ◽  
Magnetic Helicity ◽  
Topological Configuration ◽  
The Relationship

AbstractThe helicity is an important quantity to present the basic topological configuration of magnetic field transferred form the solar subatmosphere into the interplanetary space. In this paper, we present the observational solar magnetic field and the relationship with the magnetic helicity.

scholarly journals Observations of magnetic and kinetic helicity proxies

2012 ◽  
Vol 8 (S294) ◽  
pp. 13-24
Author(s):  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Active Regions ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Vector Magnetograms ◽  
Topological Configuration ◽  
The Relationship

AbstractThe helicity is important to present the basic topological configuration of magnetic field in solar atmosphere. The distribution of magnetic helicity in solar atmosphere is presented by means of the observational (vector) magnetograms. As the kinetic helicity in the solar subatmosphere can be inferred from the velocity field based on the technique of the helioseismology and used to compare with the magnetic helicity in the solar atmosphere, the observational helicities provide the important chance for the confirmation on the generation of magnetic fields in the subatmosphere and solar dynamo models also. In this paper, we present the observational magnetic and kinetic helicity in solar active regions and corresponding questions, except the relationship with solar eruptive phenomena.

scholarly journals Helicity transport from solar convection zone to interplanetary space

2012 ◽  
Vol 8 (S294) ◽  
pp. 505-518
Author(s):  
Mei Zhang
Keyword(s):  
Magnetic Field ◽  
Convection Zone ◽  
Interplanetary Space ◽  
Magnetic Helicity ◽  
Solar Photosphere ◽  
Solar Magnetic Fields ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Magnetic Flux Ropes ◽  
Solar Winds

AbstractMagnetic helicity is a physical quantity that describes field topology. It is also a conserved quantity as Berger in 1984 demonstrated that the total magnetic helicity is still conserved in the corona even when there is a fast magnetic reconnection. It is generally believed that solar magnetic fields, together with their helicity, are created in the convection zone by various dynamo processes. These fields and helicity are transported into the corona through solar photosphere and finally released into the interplanetary space via various processes such as coronal mass ejections (CMEs) and solar winds. Here I will give a brief review on our recent works, first on helicity observations on the photosphere and how to understand these observations via dynamo models. Mostly, I will talk about what are the possible consequences of magnetic helicity accumulation in the corona, namely, the formation of magnetic flux ropes, CMEs taking place as an unavoidable product of coronal evolution, and flux emergences as a trigger of CMEs. Finally, I will address on in what a form magnetic field in the interplanetary space would accommodate a large amount of magnetic helicity that solar dynamo processes have been continuously producing.

scholarly journals Magnetic Helicity Estimations in Models and Observations of the Solar Magnetic Field. III. Twist Number Method

2017 ◽  
Vol 840 (1) ◽  
pp. 40 ◽  
Author(s):  
Y. Guo ◽  
E. Pariat ◽  
G. Valori ◽  
S. Anfinogentov ◽  
F. Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Magnetic Field ◽  
Magnetic Helicity ◽  
Twist Number

scholarly journals Magnetic Helicity Estimations in Models and Observations of the Solar Magnetic Field. Part I: Finite Volume Methods

2016 ◽  
Vol 201 (1-4) ◽  
pp. 147-200 ◽  
Author(s):  
Gherardo Valori ◽  
Etienne Pariat ◽  
Sergey Anfinogentov ◽  
Feng Chen ◽  
Manolis K. Georgoulis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Finite Volume ◽  
Solar Magnetic Field ◽  
Finite Volume Methods ◽  
Magnetic Helicity

Introduction to the current status of solar magnetic field measurements in China

2020 ◽  
Author(s):  
Yuanyong Deng
Keyword(s):  
Magnetic Field ◽  
Field Measurement ◽  
Solar Magnetic Field ◽  
Interplanetary Space ◽  
Field Measurements ◽  
Current Status ◽  
Magnetic Field Measurement ◽  
Magnetic Field Measurements ◽  
History Of ◽  
Early Century

<p>Solar magnetic field is a key paramters to understand the solar activity and its influence to the interplanetary space in the solar system. The solar magnetic field measurement is always an enormous challenge to the solar community. We firstly overview the history of solar magnetic field measurement since last early century and analyze the difficulty and progress of pratical methods. Then we introduce an infrared system for the accurate measurement of solar magnetic field (AIMS) and its current progress, which is supported by National Natural Science Foundation of China and also the current ongoing space based projects (ASO-S/FMG) to measure the solar magnetic field in China.</p>

scholarly journals Evolution of relative magnetic helicity

2018 ◽  
Vol 613 ◽  
pp. A27 ◽  
Author(s):  
Shangbin Yang ◽  
Jörg Büchner ◽  
Jan Skála ◽  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Corona ◽  
Magnetic Reconnection ◽  
Interplanetary Space ◽  
New Method ◽  
Magnetic Clouds ◽  
Magnetic Helicity ◽  
Bottom Boundary ◽  
The Magnetic Field

Context. For a better understanding of the dynamics of the solar corona, it is important to analyse the evolution of the helicity of the magnetic field. Since the helicity cannot be directly determined by observations, we have recently proposed a method to calculate the relative magnetic helicity in a finite volume for a given magnetic field, which however required the flux to be balanced separately on all the sides of the considered volume. Aims. We developed a scheme to obtain the vector potential in a volume without the above restriction at the boundary. We studied the dissipation and escape of relative magnetic helicity from an active region. Methods. In order to allow finite magnetic fluxes through the boundaries, a Coulomb gauge was constructed that allows for global magnetic flux balance. The property of sinusoidal function was used to obtain the vector potentials at the 12 edges of the considered rectangular volume extending above an active region. We tested and verified our method in a theoretical fore-free magnetic field model. Results. We applied the new method to the former calculation data and found a difference of less than 1.2%. We also applied our method to the magnetic field above active region NOAA 11429 obtained by a new photospheric-data-driven magnetohydrodynamics (MHD) model code GOEMHD3. We analysed the magnetic helicity evolution in the solar corona using our new method. We find that the normalized magnetic helicity (H∕Φ2) is equal to −0.038 when fast magnetic reconnection is triggered. This value is comparable to the previous value (−0.029) in the MHD simulations when magnetic reconnection happened and the observed normalized magnetic helicity (−0.036) from the eruption of newly emerging active regions. We find that only 8% of the accumulated magnetic helicity is dissipated after it is injected through the bottom boundary. This is in accordance with the Woltjer conjecture. Only 2% of the magnetic helicity injected from the bottom boundary escapes through the corona. This is consistent with the observation of magnetic clouds, which could take magnetic helicity into the interplanetary space. In the case considered here, several halo coronal mass ejections (CMEs) and two X-class solar flares originate from this active region.

Study on Relationship between Power Grid GIC (Geomagnetically Induced Currents) and Interplanetary Disturbances

2013 ◽  
Vol 732-733 ◽  
pp. 726-730 ◽  
Author(s):  
Guan Nan Du ◽  
Lian Guang Liu ◽  
Kai Rang Wang
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Geomagnetic Field ◽  
Interplanetary Space ◽  
Dynamic Pressure ◽  
Comprehensive Analysis ◽  
Single Factor ◽  
Geomagnetically Induced Currents ◽  
Induced Currents ◽  
The Relationship

Geomagnetically induced currents (GIC) are very harmful to the power system and caused by the changes of geomagnetic field. The changing magnetic fields originate from the interplanetary space. Therefore, recognizing the relationship between GIC and interplanetary disturbances is significant for the prediction of GIC. In this paper, we collected 35 GIC events during 1999-2005 and the corresponding interplanetary data observed by ACE satellite to analyze the correlations of various interplanetary parameters with GIC. The results show that there is positive correlation between GIC amplitudes and interplanetary parameters. As a single factor, solar wind dynamic pressure (Pk) correlates best with GIC, while interplanetary electric field (Ey) and interplanetary magnetic field (|B|) also correlate well with GIC. In addition, we investigated the relationships between interplanetary parameters and GIC amplitudes for different intensities (GIC>10A, GIC>20A). Comprehensive analysis shows that Pk and Ey are the most closely parameters related to GIC.

scholarly journals The polar belts of prominence occurence as an indicator of the solar magnetic field reversal

2013 ◽  
Vol 8 (S300) ◽  
pp. 456-457
Author(s):  
Teodor Pintér ◽  
Milan Rybanský ◽  
Ivan Dorotovič
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Solar Magnetic Field ◽  
Interplanetary Space ◽  
Global Field ◽  
The Sun ◽  
Field Reversal ◽  
Global Magnetic Field ◽  
Polarity Change

AbstractThe global magnetic field of the Sun is the determining parameter of spreading the solar wind in the interplanetary space. The global field changes the polarity synchronically with the cycle of solar activity. The interesting indicator of the polarity change are the occurence so-called polar belts of the prominences. The article shows the performance of these belts on observational work from 1975 to 2009. A coordinated effort is suggested for the compilation of data from different observers following the method described by Rušin et al., 1988.

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