scholarly journals Introduction to the physics of solar eruptions and their space weather impact

2019 ◽  
Vol 377 (2148) ◽  
pp. 20190152 ◽  
Author(s):  
Vasilis Archontis ◽  
Loukas Vlahos
Keyword(s):  
Space Weather ◽  
Large Scale ◽  
Interplanetary Space ◽  
Active Regions ◽  
Solar Interior ◽  
Physical Processes ◽  
Weather Impact ◽  
Solar Eruptions ◽  
Earth Connection ◽  
Magnetic Disturbances

The physical processes, which drive powerful solar eruptions, play an important role in our understanding of the Sun–Earth connection. In this Special Issue, we firstly discuss how magnetic fields emerge from the solar interior to the solar surface, to build up active regions, which commonly host large-scale coronal disturbances, such as coronal mass ejections (CMEs). Then, we discuss the physical processes associated with the driving and triggering of these eruptions, the propagation of the large-scale magnetic disturbances through interplanetary space and the interaction of CMEs with Earth's magnetic field. The acceleration mechanisms for the solar energetic particles related to explosive phenomena (e.g. flares and/or CMEs) in the solar corona are also discussed. The main aim of this Issue, therefore, is to encapsulate the present state-of-the-art in research related to the genesis of solar eruptions and their space-weather implications. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

scholarly journals Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180096 ◽  
Author(s):  
A. Vourlidas ◽  
S. Patsourakos ◽  
N. P. Savani
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Technology Development ◽  
Action Plan ◽  
Current Status ◽  
Weather Impact ◽  
Solar Eruptions ◽  
Holding Back ◽  
Open Issues ◽  
Made In

Much progress has been made in the study of coronal mass ejections (CMEs), the main drivers of terrestrial space weather thanks to the deployment of several missions in the last decade. The flow of energy required to power solar eruptions is beginning to be understood. The initiation of CMEs is routinely observed with cadences of tens of seconds with arc-second resolution. Their inner heliospheric evolution can now be imaged and followed routinely. Yet relatively little progress has been made in predicting the geoeffectiveness of a particular CME. Why is that? What are the issues holding back progress in medium-term forecasting of space weather? To answer these questions, we review, here, the measurements, status and open issues on the main CME geoeffective parameters; namely, their entrained magnetic field strength and configuration, their Earth arrival time and speed, and their mass (momentum). We offer strategies for improving the accuracy of the measurements and their forecasting in the near and mid-term future. To spark further discussion, we incorporate our suggestions into a top-level draft action plan that includes suggestions for sensor deployment, technology development and modelling/theory improvements. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

scholarly journals Distinguishing between flaring and nonflaring active regions

2020 ◽  
Vol 639 ◽  
pp. A44
Author(s):  
Soumitra Hazra ◽  
Gopal Sardar ◽  
Partha Chowdhury
Keyword(s):  
Active Region ◽  
Magnetic Flux ◽  
Time Evolution ◽  
Large Scale ◽  
Learning Algorithm ◽  
Active Regions ◽  
Magnetic Helicity ◽  
Magnetic Parameters ◽  
Solar Eruptions ◽  
Very High

Context. Large-scale solar eruptions significantly affect space weather and damage space-based human infrastructures. It is necessary to predict large-scale solar eruptions; it will enable us to protect the vulnerable infrastructures of our modern society. Aims. We investigate the difference between flaring and nonflaring active regions. We also investigate whether it is possible to forecast a solar flare. Methods. We used photospheric vector magnetogram data from the Solar Dynamic Observatory’s Helioseismic Magnetic Imager to study the time evolution of photospheric magnetic parameters on the solar surface. We built a database of flaring and nonflaring active regions observed on the solar surface from 2010 to 2017. We trained a machine-learning algorithm with the time evolution of these active region parameters. Finally, we estimated the performance obtained from the machine-learning algorithm. Results. The strength of some magnetic parameters such as the total unsigned magnetic flux, the total unsigned magnetic helicity, the total unsigned vertical current, and the total photospheric magnetic energy density in flaring active regions are much higher than those of the non-flaring regions. These magnetic parameters in a flaring active region evolve fast and are complex. We are able to obtain a good forecasting capability with a relatively high value of true skill statistic. We also find that time evolution of the total unsigned magnetic helicity and the total unsigned magnetic flux provides a very high ability of distinguishing flaring and nonflaring active regions. Conclusions. We can distinguish a flaring active region from a nonflaring region with good accuracy. We confirm that there is no single common parameter that can distinguish all flaring active regions from the nonflaring regions. However, the time evolution of the top two magnetic parameters, the total unsigned magnetic flux and the total unsigned magnetic helicity, have a very high distinguishing capability.

scholarly journals Sources of solar energetic particles

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180095 ◽  
Author(s):  
Loukas Vlahos ◽  
Anastasios Anastasiadis ◽  
Athanasios Papaioannou ◽  
Athanasios Kouloumvakos ◽  
Heinz Isliker
Keyword(s):  
Solar Corona ◽  
Space Weather ◽  
Solar Flares ◽  
Large Scale ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Plasma Parameters ◽  
Current Sheets ◽  
Solar Eruptions ◽  
Magnetohydrodynamic Simulations

Solar energetic particles are an integral part of the physical processes related with space weather. We present a review for the acceleration mechanisms related to the explosive phenomena (flares and/or coronal mass ejections, CMEs) inside the solar corona. For more than 40 years, the main two-dimensional cartoon representing our understanding of the explosive phenomena inside the solar corona remained almost unchanged. The acceleration mechanisms related to solar flares and CMEs also remained unchanged and were part of the same cartoon. In this review, we revise the standard cartoon and present evidence from recent global magnetohydrodynamic simulations that support the argument that explosive phenomena will lead to the spontaneous formation of current sheets in different parts of the erupting magnetic structure. The evolution of the large-scale current sheets and their fragmentation will lead to strong turbulence and turbulent reconnection during solar flares and turbulent shocks. In other words, the acceleration mechanism in flares and CME-driven shocks may be the same, and their difference will be the overall magnetic topology, the ambient plasma parameters, and the duration of the unstable driver. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

scholarly journals The emergence of magnetic flux and its role on the onset of solar dynamic events

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180387 ◽  
Author(s):  
V. Archontis ◽  
P. Syntelis
Keyword(s):  
Magnetic Flux ◽  
Large Scale ◽  
Spatial Scales ◽  
Active Regions ◽  
Short Review ◽  
The Sun ◽  
Flux Emergence ◽  
Dynamic Events ◽  
Solar Eruptions ◽  
Solar Dynamics

A plethora of solar dynamic events, such as the formation of active regions, the emission of jets and the occurrence of eruptions is often associated with the emergence of magnetic flux from the interior of the Sun to the surface and above. Here, we present a short review on the onset, driving and/or triggering of such events by magnetic flux emergence. We briefly describe some key observational examples, theoretical aspects and numerical simulations, towards revealing the mechanisms that govern solar dynamics and activity related to flux emergence. We show that the combination of important physical processes like shearing and reconnection of magnetic fieldlines in emerging flux regions or at their vicinity can power some of the most dynamic phenomena in the Sun on various temporal and spatial scales. Based on previous and recent observational and numerical studies, we highlight that, in most cases, none of these processes alone can drive and also trigger explosive phenomena releasing considerable amount of energy towards the outer solar atmosphere and space, such as flares, jets and large-scale eruptions (e.g. coronal mass ejections). In addition, one has to take into account the physical properties of the emerging field (e.g. strength, amount of flux, relative orientation to neighbouring and pre-existing magnetic fields, etc.) in order to better understand the exact role of magnetic flux emergence on the onset of solar dynamic events. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

On Space Weather factors which can impact terrestrial physical and biological processes

2020 ◽  
Author(s):  
Olga Stupishina ◽  
Elena Golovina
Keyword(s):  
Human Health ◽  
Space Weather ◽  
Interplanetary Space ◽  
Electromagnetic Spectrum ◽  
Biological Processes ◽  
Weather Factors ◽  
Weather Impact ◽  
Saint Petersburg ◽  
The Impact ◽  
Weather Characteristics

<p>The main idea of our work is to find out the perspective points for the investigation of space factors which can impact physical and biological processes on Earth surface. Some decades ago the complex of those factors was named as “Space Weather”. So the main purpose of our work is to discover the connection between Space Weather and Terrestrial Weather as well as the impact of this environmental complex (Space Weather plus Terrestrial Weather) on biological objects and thereby on the human health.</p><p>The first part of the presented work contains the description of the Space Weather characteristics for the appearance moments of very long-live (more than 10 days) atmosphere pressure systems on different terrestrial latitude locations. These Long-live Pressure Systems (LPS) are interesting for us because some of them (namely anticyclones) can block pressure fields so they can create some dangerous situations for the human health as well as for the human activity. The different terrestrial latitude locations were: (1) Saint-Petersburg (59<sup>o</sup>57‘N, 30<sup>o</sup>19‘E) and (2) Tambov (52<sup>o</sup>43‘N, 41<sup>o</sup>27‘E). This latitude difference in observations is interesting for us because we know about the different affect of Space Weather variations on northern and southern places so we want to study this difference.  The time-intervals were: (1) 1999-2014 years (Saint-Petersburg), (2) 2007-2014 years (Tambov). Space Weather parameters were: (1) global  variations of Solar Activity (SA) parameters; (2) daily characteristics of the SA flare component in various bands of the electromagnetic spectrum; (3) variations of Interplanetary Space characteristics in Earth vicinity; (4) variations of daily statistics of Geomagnetic Field (GMF) characteristics. For the appearance moments of LPS we have discovered the interesting behaviour for follow Space Weather characteristics: variations of all global SA indices, variations of low energy (C-class) X-ray solar flares number, variations of proton fluxes, and variations of GMF parameters daily statistics. Also we have discovered the terrestrial-latitude difference in the atmosphere response on the Space Weather impact.</p><p>The second part of our work contains the results of investigation of environmental (Space Weather plus Terrestrial Weather) impact on human health. This study was done for Saint-Petersburg region (the northern place from the previous point of our investigation). The human health status was indicated by: (1) Cardiac Rhythm Variations (CRV) of patients in the clinic of Medicine Academy, Sudden Cardiac Deaths (SCD) in Research Institute of Emergency Medicine, facts of hard situation in 6 local clinics in different places of Saint-Petersburg and its suburb. We have found out that the dramatic cardiac events (CRV extrema, SCD maxima, hard days in clinics) are connected with variations of solar radio bursts number (the burst type is “noise storm”), the spread daily statistics (coefficient of variation) of GMF z-component and with spread daily statistics (coefficient of oscillation) of air temperature.</p><p>Results of our work may be used as the base for the hazard environmental monitoring.</p>

Observation-based modelling of magnetised CMEs in the inner heliosphere with EUHFORIA

2020 ◽  
Author(s):  
Camilla Scolini ◽  
Jens Pomoell ◽  
Emmanuel Chané ◽  
Stefaan Poedts ◽  
Luciano Rodriguez ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Space Weather ◽  
Interplanetary Space ◽  
Dynamic Pressure ◽  
Weather Prediction ◽  
Primary Source ◽  
Field Orientation ◽  
Weather Impact ◽  
The Impact ◽  
Inner Heliosphere

<p>Coronal Mass Ejections (CMEs) are the primary source of strong space weather disturbances at Earth and other locations in the heliosphere. Understanding the physical processes involved in their formation at the Sun, propagation in the heliosphere, and impact on planetary bodies is therefore critical to improve current space weather predictions throughout the heliosphere. The capability of CMEs to drive strong space weather disturbances at Earth and other planetary and spacecraft locations primarily depends on their dynamic pressure, internal magnetic field strength, and magnetic field orientation at the impact location. In addition, phenomena such as the interaction with the solar wind and other solar transients along the way, or the pre-conditioning of interplanetary space due to the passage of previous CMEs, can significantly modify the properties of individual CMEs and alter their ultimate space weather impact. Investigating and modeling such phenomena via advanced physics-based heliospheric models is therefore crucial to improve the space weather prediction capabilities in relation to both single and complex CME events. </p><p>In this talk, we present our progress in developing novel methods to model CMEs in the inner heliosphere using the EUHFORIA MHD model in combination with remote-sensing solar observations. We discuss the various observational techniques that can be used to constrain the initial CME parameters for EUHFORIA simulations. We present current efforts in developing more realistic magnetised CME models aimed at describing their internal magnetic structure in a more realistic fashion. We show how the combination of these two approaches allows the investigation of CME propagation and evolution throughout the heliosphere to a higher level of detail, and results in significantly improved predictions of CME impact at Earth and other locations in the heliosphere. Finally, we discuss current limitations and future improvements in the context of studying space weather events throughout the heliosphere.</p>

scholarly journals An Insight into Space Weather

2017 ◽  
Vol 2 (1) ◽  
pp. 46-57
Author(s):  
Ashish Mishra ◽  
Mukul Kumar
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Power Grids ◽  
The Sun ◽  
Solar Winds ◽  
The Earth ◽  
Earth Connection ◽  
Insight Into

The present article gives a brief overview of space weather and its drivers. The space weather is of immense importance for the spaceborne and ground-based technological systems. The satellites, the power grids, telecommunication and in severe conditions the human lives are at risk. The article covers the effects of solar transient activities (e.g. Solar flares, Coronal mass ejections and Solar winds etc.) and their consequences on the Earth’s atmosphere. The space weather is the change in the conditions of interplanetary space because of the solar transient activities. We also discussed the importance of the solar wind which is a continuous flow of the charged energy particles from the Sun to the Earth in respect of the space weather. This article also put light on the Sun-Earth connection and effects of the space weather on it. The Earth’s magnetosphere, formed by the interaction of solar wind and Earth’s magnetic field behaves like a shield for the Earth against the solar wind.

scholarly journals Seismic Forecasting of Solar Activity

2002 ◽  
Vol 12 ◽  
pp. 378
Author(s):  
D.C. Braun ◽  
C. Lindsey
Keyword(s):  
Solar Activity ◽  
Space Weather ◽  
Solar Limb ◽  
Active Regions ◽  
Solar Interior ◽  
The Sun ◽  
Near Surface ◽  
Near Earth Space ◽  
Doppler Imager ◽  
East Limb

Computational seismic holography, applied to Solar Oscillations Investigation -Michelson Doppler Imager (SOI-MDI) data fromSOHO, has recently given us the first images of an active region on the far side of the Sun(Lindsey & Braun 2000). The advent of phase-coherent seismic imaging is now allowing us quite literally to look into the solar interior from a local perspective, indeed to see through the solar interior acoustically to its far surface. Solar activity is critical to near-Earth space weather. A great deal of effort has been invested towards the prediction of flares and CMEs, based on the formidable presence of active regions on the near solar surface. Active regions can emerge rapidly from beneath the photosphere or appear on the east limb with relatively little warning. Because of this, the ability to anticipate the appearances of active regions will contribute substantially to forecasts of space weather on time scales of more than about a day. In collaboration with Dr. Phil Scherrer and the MDI team at Stanford University we are currently deriving far-side images from the lower resolution “medium-l” SOI-MDI Dopplergrams, which are obtained continuously through the year and arrive at MDI headquarters within 24 hours of their acquisition by theSOHOspacecraft. We are therefore already capable of locating large far-side active regions and predicting their appearance on the east solar limb to within a few hours more than a week in advance. In addition, ground-based networks such as GONG will soon have the capability for “real-time helioseismology”, and will be routinely monitoring the far surface of the Sun, and perhaps beneath the near surface, for emerging solar activity.

scholarly journals The source and engine of coronal mass ejections

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180094 ◽  
Author(s):  
Manolis K. Georgoulis ◽  
Alexander Nindos ◽  
Hongqi Zhang
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Magnetic Energy ◽  
Active Regions ◽  
Magnetic Polarity ◽  
X Rays ◽  
Polarity Inversion ◽  
Magnetic Flux Ropes ◽  
Causal Sequence

Coronal mass ejections (CMEs) are large-scale expulsions of coronal plasma and magnetic field propagating through the heliosphere. Because CMEs are observed by white-light coronagraphs which, by design, occult the solar disc, supporting disc observations (e.g. in EUV, soft X-rays, Halpha and radio) must be employed for the study of their source regions and early development phases. We review the key properties of CME sources and highlight a certain causal sequence of effects that may occur whenever a strong (flux-massive and sheared) magnetic polarity inversion line develops in the coronal base of eruptive active regions (ARs). Storing non-potential magnetic energy and helicity in a much more efficient way than ARs lacking strong polarity inversion lines, eruptive regions engage in an irreversible course, making eruptions inevitable and triggered when certain thresholds of free energy and helicity are crossed. This evolution favours the formation of pre-eruption magnetic flux ropes. We describe the steps of this plausible path to sketch a picture of the pre-eruptive phase of CMEs that may apply to most events, particularly the ones populating the high end of the energy/helicity distribution, that also tend to have the strongest space-weather implications. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

scholarly journals Ionospheric response to solar and interplanetary disturbances: a Swarm perspective

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180098 ◽  
Author(s):  
G. Balasis ◽  
C. Papadimitriou ◽  
A. Z. Boutsi
Keyword(s):  
Solar Cycle ◽  
Electric Fields ◽  
Space Weather ◽  
Low Earth Orbit ◽  
Topside Ionosphere ◽  
Plasma Instabilities ◽  
Radio Communications ◽  
Weather Impact ◽  
Ionospheric Response ◽  
Solar Eruptions

The ionospheric response to solar and interplanetary disturbances has been the subject of intense study for several decades. For 5 years now, the European Space Agency's Swarm fleet of satellites surveys the Earth's topside ionosphere, measuring magnetic and electric fields at low-Earth orbit with unprecedented detail. Herein, we study in situ the ionospheric response in terms of the occurrence of plasma instabilities based on 2 years of Swarm observations. Plasma instabilities are an important element of space weather because they include irregularities like the equatorial spread F events, which are responsible for the disruption of radio communications. Moreover, we focus on three out of the four most intense geospace magnetic storms of solar cycle 24 that occurred in 2015, including the St Patrick's Day event, which is the strongest magnetic storm of the present solar cycle. We examine the associated ionospheric response at Swarm altitudes through the estimation of a Swarm Dst-like index. The newly proposed Swarm derived Dst index may be suitable for space weather applications. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

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