scholarly journals Signature of the turbulent component of the solar dynamo on active region scales and its association with flaring activity

2021 ◽  
Vol 507 (3) ◽  
pp. 3698-3706
Author(s):  
Valentina I Abramenko
Keyword(s):  
Spatial Scales ◽  
Active Regions ◽  
Convective Zone ◽  
Solar Dynamo ◽  
Solar Cycles ◽  
Dynamo Action ◽  
Turbulent Dynamo ◽  
Time Period

ABSTRACT It is a challenging problem to obtain observational evidence of the turbulent component of solar dynamo operating in the convective zone because the dynamo action is hidden below the photosphere. Here we present results of a statistical study of flaring active regions (ARs) that produced strong solar flares of an X-ray class X1.0 and higher during a time period that covered solar cycles 23 and 24. We introduced a magneto-morphological classification of ARs, which allowed us to estimate the possible contribution of the turbulent component of the dynamo into the structure of an AR. We found that in 72 per cent of cases, flaring ARs do not comply with the empirical laws of the global dynamo (frequently they are not bipolar ARs or, if they are, they violate the Hale polarity law, the Joy law, or the leading sunspot prevalence rule). This can be attributed to the influence of the turbulent dynamo action inside the convective zone on spatial scales of typical ARs. Thus, it appears that the flaring is governed by the turbulent component of the solar dynamo. The contribution into the flaring from these AR ‘violators’ (irregular ARs) is enhanced during the second maximum and the descending phase of a solar cycle, when the toroidal field weakens and the influence of the turbulent component becomes more pronounced. These observational findings are in consensus with a concept of the essential role of non-linearities and turbulent intermittence in the magnetic fields generation inside the convective zone, which follows from dynamo simulations.

scholarly journals Magnetic power spectrum in the undisturbed solar photosphere

2020 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Valentina Abramenko ◽  
Olga Kutsenko
Keyword(s):  
Power Spectrum ◽  
Power Spectra ◽  
Active Regions ◽  
Reliable Estimate ◽  
Small Scale ◽  
Solar Photosphere ◽  
Dynamo Action ◽  
Quiet Sun ◽  
Turbulent Dynamo ◽  
Wide Range

Using the magnetic field data obtained with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), an investigation of magnetic power spectra in the undisturbed solar photosphere was performed. The results are as follows. 1) To get a reliable estimate of a magnetic power spectrum from the uniformly distributed quiet-sun magnetic flux, a sample pattern of no less than 300 pixels length should be adopted. With smaller patterns, energy on all observable scales might be overestimated. 2) For patterns of different magnetic intensity (e.g., a coronal hole, a quiet-sun area, an area of supergranulation), the magnetic power spectra in a range of (2.5-10) Mm exhibit very close spectral indices of about -1. The observed spectrum is more shallow than the Kolmogorov-type spectrum (with a slope of -5/3) and it differs from steep spectra of active regions. Such a shallow spectrum cannot be explained by the only direct Kolmogorov’s cascade, but it can imply a small-scale turbulent dynamo action in a wide range of scales: from tens of megameters down to at least 2.5 Mm. On smaller scales, the HMI/SDO data do not allow us to reliably derive the shape of the spectrum. 3) Data make it possible to conclude that a uniform mechanism of the small-scale turbulent dynamo is at work all over the solar surface outside active regions.

scholarly journals Toward a classification of the Central Pacific El Niño

2012 ◽  
Vol 3 (2) ◽  
pp. 979-998
Author(s):  
M. Pascolini-Campbell ◽  
D. Zanchettin ◽  
O. Bothe ◽  
C. Timmreck ◽  
D. Matei ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Central Pacific ◽  
Natural Climate Variability ◽  
Central Pacific El Niño ◽  
Robust Identification ◽  
Time Period ◽  
Natural Climate

Abstract. We investigate the various methods currently available for distinguishing between the Central Pacific (CP) El Niño (or "El Niño Modoki") and the canonical El Niño by considering 10 different methods and 5 sea surface temperature (SST) datasets from 1880 to 2010. Years which are classified as CP El Niños with the greatest convergence between method and SST dataset are considered to provide a more robust identification of these events. The results identify 13 yr which are classified the most consistently as CP events: 1885/1886, 1914/1915, 1940/1941, 1958/1959, 1963/1964, 1968/1969, 1977/1978, 1986/1987, 1991/1992, 2002/2003, 2003/2004, 2004/2005 and 2009/2010. Our findings also indicate the persistence of CP events throughout the time period investigated, inciting the role of multidecadal natural climate variability in generating CP El Niños.

scholarly journals Magnetic helicity of solar active regions

2008 ◽  
Vol 4 (S257) ◽  
pp. 133-143
Author(s):  
A. Nindos
Keyword(s):  
Unique Feature ◽  
Interplanetary Space ◽  
Active Regions ◽  
Convective Zone ◽  
Magnetic Helicity ◽  
Solar Eruptions ◽  
History Of ◽  
Ideal Tool ◽  
The Magnetic Field

AbstractMagnetic helicity is a quantity that describes the linkage and twistedness/shear in the magnetic field. It has the unique feature that it is probably the only physical quantity which is approximately conserved even in resistive MHD. This makes magnetic helicity an ideal tool for the exploration of the physics of eruptive events. The concept of magnetic helicity can be used to monitor the whole history of a CME event from the emergence of twisted magnetic flux from the convective zone to the eruption and propagation of the CME into interplanetary space. In this article, I discuss the sources of the magnetic helicity injected into active regions and the role of magnetic helicity in the initiation of solar eruptions.

scholarly journals Rogue Active Regions and the Inherent Unpredictability of the Solar Dynamo

2018 ◽  
Vol 13 (S340) ◽  
pp. 307-312 ◽  
Author(s):  
Kristóf Petrovay ◽  
Melinda Nagy
Keyword(s):  
Solar Activity ◽  
Tilt Angle ◽  
Active Regions ◽  
Surface Flux ◽  
Transport Modeling ◽  
Current Understanding ◽  
Solar Cycles ◽  
Flux Transport ◽  
New Developments

AbstractNew developments in surface flux transport modeling and theory of flux transport dynamos have given rise to the notion that certain large active regions with anomalous properties (location, tilt angle and/or Hale/non-Hale character) may have a major impact on the course of solar activity in subsequent years, impacting also on the amplitude of the following solar cycles. Here we discuss our current understanding of the role of such “rogue” active regions in cycle-to-cycle variations of solar activity.

Flux emergence rate of active regions as a probe for turbulent dynamo action

2018 ◽  
Vol 13 (S340) ◽  
pp. 299-300
Author(s):  
Aleksandr S. Kutsenko ◽  
Valentina I. Abramenko
Keyword(s):  
Magnetic Flux ◽  
Numerical Simulations ◽  
Flux Tube ◽  
Active Regions ◽  
Magnetic Flux Tube ◽  
Flux Emergence ◽  
Dynamo Action ◽  
Turbulent Dynamo ◽  
Emergence Rate ◽  
The Difference

AbstractWe analyze the flux emergence rate of solar active regions (ARs). Numerical simulations by other authors suggest that the flux emergence rate depends on the AR’s twist. To prove this statement observationally, we make a comparison of the flux emergence rate and twist of 215 emerging ARs. Our results confirm that the correlation exists: the higher the twist the higher the flux emergence rate of an AR. We suppose that the difference in the twist can be caused by chaotic influence of the convective plasma motions on the lifting magnetic flux tube.

Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results

1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo
Keyword(s):  
Solar Activity ◽  
Energy Balance ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
General Problem ◽  
Solar Rotation ◽  
Active Regions ◽  
Physical Conditions ◽  
Dynamic Phenomena

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.

Raiders Activity on the Market for Corporate Control as a Product of Coercive Entrepreneurship Evolution

2007 ◽  
pp. 80-92
Author(s):  
A. Kireev
Keyword(s):  
Corporate Control ◽  
Role Of Government ◽  
Market For Corporate Control ◽  
Basic Characteristics

The paper studies the problem of raiders activity on the market for corporate control. This activity is considered as a product of coercive entrepreneurship evolution. Their similarities and sharp distinctions are shown. The article presents the classification of raiders activity, discribes its basic characteristics and tendencies, defines the role of government in the process of its transformation.

ASPECTS IN BUILDING A COMPANY WEB-SITE AND ITS ROLE FOR THE DEVELOPMENT OF BUSINESS

2018 ◽  
pp. 117-124
Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva
Keyword(s):  
Life Cycle ◽  
Web Site ◽  
The Internet ◽  
A Company ◽  
The Web ◽  
Design Construction ◽  
Made In ◽  
Site Types

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.

POLÍTICAS DE ESCALA E A CONFORMAÇÃO DE ESTRATÉGIAS-REDE DAS AÇÕES COLETIVAS NO ESPAÇO SISALEIRO DA BAHIA

GEOgraphia ◽  
2018 ◽  
Vol 19 (41) ◽  
pp. 39
Author(s):  
Agripino Souza Coelho Neto
Keyword(s):  
Political Action ◽  
Spatial Scales ◽  
Spatial Behavior ◽  
Collective Actions ◽  
Collective Behaviors ◽  
Rural Workers ◽  
Scale Levels ◽  
Scale Network ◽  
Comme Point

Resumo: O presente texto pretende analisar o papel das ações coletivas (associações, cooperativas e sindicatos de agricultores) no acionamento e na ativação das escalas geográficas para o desenvolvimento de suas atividades. O estudo foi realizado no Espaço Sisaleiro da Bahia (Brasil), onde um conjunto significativo de associações e cooperativas de agricultores e sindicatos de trabalhadores rurais tem se organizado em torno das escalas espaciais para viabilizar sua ação político-institucional e econômico-produtiva. A ação desses coletivos organizados em rede tem permitido a conformação e o fortalecimento de novas escalas de ação política, como no caso da criação do conselho territorial para viabilização da implantação de políticas de governo. Cooperativas, associações e sindicatos se apoiam nas escalas para compor organizações em diferentes níveis escalares (escala local, escala regional, escala do estado federado e escala nacional), buscando fortalecer seus propósitos e ampliar seu poder de barganha e influência. Analisando o comportamento espacial dessas variadas modalidades de ações coletivas, é possível considerar que elas desenvolvem políticas de escala, ou seja, a escala passa a significar muito mais que uma categoria de análise, mas se torna uma categoria da prática social e política. Nesse sentido, parte-se do pressuposto de que os grupos humanos produzem e tornam efetivas suas próprias escalas visando a alcançar suas metas e organizar seus comportamentos coletivos. Palavras-chave: Escala. Rede. Cooperativismo. Associativismo. Sindicalismo. Espaço Sisaleiro da Bahia. SCALE POLICIES AND THE DEVELOPMENT OF NETWORK STRATEGIES OF COLLECTIVE ACTIONS IN THE SISAL REGION OF BAHIA (BRAZIL)Abstract: This paper aims to analyze the role of collective initiatives of associations, cooperatives and farmers’ unions in the mobilization and activation of geographical scales for the development of their activities. The study was conducted in the Sisal Region of Bahia (Brazil), where a significant number of farmers associations and cooperatives and rural workers’ unions have been organizing their actions around spatial scales to enable their political-institutional and economic-productive influence. The gathering and action of these organized groups in a network have allowed the establishment and strengthening of new scales of political action, as seem in the case of the creation of a territorial council to facilitate the implementation of government policies. Cooperatives, associations, and unions rely on scales to form organizations at different scale levels (local, regional, federal and national scales), seeking to strengthen their performance and increase their bargaining power and influence. After analyzing the spatial behavior of these various forms of collective actions, it’s reasonable to say that they develop scale policies, which means the scale becomes more than a category of analysis, but also a category of social and political practice. In this sense, it’s assumed that human groups produce and utilize the scales in order to reach their goals and organize their own collective behaviors. Keywords: Scale. Network. Cooperativism. Associativism. Syndicalism. Sisal Region of Bahia. POLITIQUES D’ÉCHELLE ET FORMATION DES STRATÉGIES-RÉSEAU DES ACTIONS COLLECTIVES DANS LA RÉGION DU SISAL DE L’ÉTAT DE BAHIA Resumé: Cet article analyse le rôle des actions collectives (associations, coopératives et syndicats d’agriculteurs) dans la prise en compte et l’utilisation des échelles géographiques pour le développement de leurs activités. L’étude a été menée dans la région du sisal à Bahia (Brésil), où un ensemble important d’associations et de coopératives d’agriculteurs et de syndicats de travailleurs ruraux se sont organisés autour d’échelles spatiales pour que puisse être mise en place leur action politique et institutionnelle, économique et productive. L’action de ces groupements organisés en réseaux a permis la conformation et le renforcement de nouvelles échelles d’action politique, comme lors de la création du conseil territorial, pour permettre la mise en œuvre des politiques gouvernementales. Les coopératives, les associations et les syndicats prennent les échelles comme point de départ pour former des organisations à différents niveaux scalaires (échelle locale, échelle régionale, échelle fédérée et échelle nationale), dans le but de renforcer leurs objectifs et d’accroître leur pouvoir de négociation et d’influence. Si nous analysons le comportement spatial de ces diverses formes d’action collective il est possible de considérer qu’ils développent des politiques d’échelle, à savoir l’échelle vient signifier bien plus qu’une catégorie d’analyse, puisqu’elle devient une catégorie de la pratique sociale et politique. En ce sens, on suppose que les groupes humains produisent et rendent efficaces leurs propres échelles pour atteindre leurs objectifs et organiser leurs comportements collectifs. Mots-clés: Échelle. Réseau. Coopérativisme. Associations. Syndicalisme. Région du sisal de l’État de Bahia.

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