scholarly journals Commission 10: Solar Activity

2005 ◽  
Vol 1 (T26A) ◽  
pp. 75-88
Author(s):  
Donald B. Melrose ◽  
James A. Klimchuk ◽  
A.O. Benz ◽  
I.J.D. Craig ◽  
N. Gopalswamy ◽  
...  
Keyword(s):  
Solar Activity ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Coronal Loops ◽  
Theoretical Concepts ◽  
Near Earth Space ◽  
Solar Observations ◽  
Extensive List

AbstractCommission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth “space weather”.Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather.The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context.The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses.

scholarly journals Solar Dynamical Processes II

2019 ◽  
Vol 6 (1) ◽  
pp. 1-13
Author(s):  
Ashish Mishra ◽  
Mukul Kumar
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Coronal Holes ◽  
High Energy ◽  
Small Scale ◽  
The Sun ◽  
Dynamical Processes ◽  
Wide Range

The present article is the successor of Solar Dynamical Processes I. The previous article was focused on the Sun, its magnetic field with an emphasis on various dynamical processes occurring on the Sun, e.g. sunspots, prominence and bright points which in turn plays a fundamental role in regulating the space weather. This article is emphasized on the solar dynamical processes and develop an extensive understanding of the various phenomena involved in their origin. The article also covers various models and hypothesis put forward by pioneer scientists on the basis of their observation by space-borne and ground-based instruments. This article shade light over a wide range of dynamical processes e.g., solar flares, coronal mass ejections, solar jets and coronal holes. Solar jets, the small-scale transient activities are found to have association with the other transient activities (e.g., mini-flares and mini-filaments). Flares as well as the coronal mass ejections are responsible for releasing a large amount of high energy charged particles and magnetic flux into the interplanetary space, and are being considered as the main drivers of space weather.

scholarly journals SOLAR SPECTROPOLARIMETER FOR SPACE WEATHER FORECAST

2019 ◽  
Vol 5 (4) ◽  
pp. 21-26
Author(s):  
Evgeniy Ivanov ◽  
Aleksey Gubin ◽  
Sergey Lesovoi ◽  
Ramses Zaldivar Estrada
Keyword(s):  
Solar Activity ◽  
Space Weather ◽  
Linear Polarization ◽  
Coronal Mass Ejections ◽  
Software Defined Radio ◽  
Low Cost ◽  
Weather Forecast ◽  
The Internet ◽  
Type Ii ◽  
Continuous Observation

We propose a project of the meter wavelength range solar spectropolarimeter designed for a ground-based network developing for space weather forecast. The Software-Defined Radio (SDR) solution is chosen to meet such instrument network requirements as specification identity, low cost, possibility of controlling and transmitting data remotely via the Internet. Along with these requirements, the proposed SDR solution allows us to measure Stokes I and V easily, which contrasts the proposed instrument with e-CALLISTO network spectropolarimeters, most of which can record only one linear polarization. Deployment of such instruments at various longitudes will allow continuous observation of type II bursts, often related to coronal mass ejections (CMEs) — the most geoeffective solar activity events that affect the space weather significantly.

scholarly journals Optical instrumentation for chromospheric monitoring during solar cycle 25 at Paris and Côte d’Azur observatories

2020 ◽  
Vol 10 ◽  
pp. 31
Author(s):  
Jean-Marie Malherbe ◽  
Thierry Corbard ◽  
Kevin Dalmasse
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Calibration Method ◽  
Line Profiles ◽  
Short Term ◽  
Optical Instruments ◽  
Dynamic Events

We present the observing program proposed by Paris and Côte d’Azur Observatories for monitoring solar activity during the upcoming cycle 25 and providing near real time images and movies of the chromosphere for space-weather research and applications. Two optical instruments are fully dedicated to this task and we summarize their capabilities. Short-term and fast-cadence observations of the chromosphere will be performed automatically at Calern observatory (Côte d’Azur), where dynamic events, as flare development, Moreton waves, filament instabilities and Coronal Mass Ejections onset, will be tracked. This new set of telescopes will operate in 2021 with narrow bandpass filters selecting Hα and CaII K lines. We present the instrumental design and a simulation of future images. At Meudon, the Spectroheliograph is well adapted to the long-term and low-cadence survey of chromospheric activity by recently improved and optimized spectroscopic means. Surface scans deliver daily (x, y, λ) datacubes of Hα, CaII K and CaII H line profiles. We describe the nature of available data and emphasize the new calibration method of spectra.

The pancaking of coronal mass ejections: an in situ attestation

2020 ◽  
Vol 493 (1) ◽  
pp. L16-L21 ◽  
Author(s):  
Anil N Raghav ◽  
Zubair I Shaikh
Keyword(s):  
Cross Section ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Arrival Time ◽  
Interplanetary Space ◽  
Morphological Evolution ◽  
Circular Cross Section ◽  
Primary Concern ◽  
The Cross

ABSTRACT The interplanetary counterparts of coronal mass ejections (ICMEs) are the leading driver of severe space weather. Their morphological evolution in interplanetary space and the prediction of their arrival time at Earth are the ultimate focus of space weather studies, because of their scientific and technological effects. Several investigations in the last couple of decades have assumed that ICMEs have a circular cross-section. Moreover, various models have also been developed to understand the morphology of ICMEs based on their deformed cross-section. In fact, simulation studies have suggested that the initial circular cross-section flattens significantly during their propagation in the solar wind and this is referred to as ‘pancaking’. However, an observational verification of this phenmenon is still pending and it will eventually be the primary concern of several morphological models. Here, we report the first unambiguous observational evidence of extreme flattening of the cross-section of ICMEs, similar to pancaking, based on in situ measurements of 30 ICME events. In fact, we conclude that the cross-section of ICME flux ropes transformed into a two-dimensional planar magnetic structure. Such a deformed morphological feature not only alters the prediction of their arrival time but also has significant implications in solar-terrestrial physics, the energy budget of the heliosphere, charged particle energization, turbulence dissipation and enhanced geo-effectiveness, etc.

scholarly journals SOLAR SPECTROPOLARIMETER FOR SPACE WEATHER FORECAST

2019 ◽  
Vol 5 (4) ◽  
pp. 26-33
Author(s):  
Evgeniy Ivanov ◽  
Aleksey Gubin ◽  
Sergey Lesovoi ◽  
Ramses Zaldivar Estrada
Keyword(s):  
Solar Activity ◽  
Space Weather ◽  
Linear Polarization ◽  
Coronal Mass Ejections ◽  
Software Defined Radio ◽  
Low Cost ◽  
Weather Forecast ◽  
The Internet ◽  
Type Ii ◽  
Continuous Observation

We propose a project of the meter wavelength range solar spectropolarimeter designed for a ground-based network developing for space weather forecast. The Software-Defined Radio (SDR) solution is chosen to meet such instrument network requirements as specification identity, low cost, possibility of controlling and transmitting data remotely via the Internet. Along with these requirements, the proposed SDR solution allows us to measure Stokes I and V easily, which contrasts the proposed instrument with e-CALLISTO network spectropolarimeters, most of which can record only one linear polarization. Deployment of such instruments at various longitudes will allow continuous observation of type II bursts, often related to coronal mass ejections (CMEs) — the most geoeffective solar activity events that affect the space weather significantly.

The Science of Space Weather: From Bit Flips to Exoplanets

2021 ◽  
Author(s):  
Janet G Luhmann
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Space Weather ◽  
Interplanetary Space ◽  
Planetary Science ◽  
In Situ Measurements ◽  
Space Environment ◽  
The Sun ◽  
Multiple Imaging

<p>While the term ‘space weather’ remains to some synonymous with operational anomalies on spacecraft, communications interruptions, and other practical matters, its broader implications extend across the EGU and beyond. Much of the science underlying space weather has to do with how our star, the Sun, affects the space environment at Earth’s orbit. We are lucky to be living at a time where information from both remote sensing (especially imaging at visible, x-ray and EUV wavelengths) and in-situ measurements (of plasmas, magnetic fields, and energetic particles) have provided unprecedented pictures of the Sun and knowledge of its extended atmosphere, the solar wind. Building on early forays into interplanetary space and deployments of coronagraphs with the Helios and SMM missions in the 70s and 80s, the Ulysses mission reconnaissance far above the ecliptic and the launch of Yohkoh’s and SOHO’s imagers in the 90s, and the long-term ‘monitoring’ of both the Sun and the conditions upstream of the Earth on SOHO, WIND and ACE, the STEREO mission opened a floodgate to research focused on solar activity and its heliospheric and terrestrial consequences. Physics-based, often semi-empirical 3D models increasingly came into widespread use for reconstructing and interpreting the multiple imaging perspectives and multipoint in-situ measurements that the twin STEREO spacecraft, combined with Earth-viewpoint assets (including the GONG ground-based network, and as of 2010, SDO magnetographs), provided on a regular basis. These observations and models together transformed perceptions of phenomena ranging from coronal structure to solar wind sources to eruptive phenomena and consequences, and the tools used to study and forecast them. Now Parker Solar Probe and Solar Orbiter are probing details of the still unexplored regions closer to the Sun than Mercury’s orbit, with the goal of completing that part of the solar/solar wind connection puzzle. And the overall science results from these observations and analysis efforts have not been confined to heliophysics, having especially influenced planetary science and astrophysics. They are seen in recreations of long-past scenarios when our Sun and solar system were evolving, in investigations of solar activity impacts including auroral emissions at the planets,  and in applications to distant planetary systems around other ‘Suns’. That these lofty implications are related to the bit flips and static ‘noise’ first identified with ‘space weather’, provides one of the interesting connections, and still ongoing journeys/stories, within EGU’s research universe.</p>

A DEFT Way to Forecast Solar Flares

2021 ◽  
Vol 922 (2) ◽  
pp. 218
Author(s):  
Larisza D. Krista ◽  
Matthew Chih
Keyword(s):  
Space Weather ◽  
Solar Flares ◽  
Extreme Ultraviolet ◽  
Weather Forecast ◽  
Start Time ◽  
X Ray ◽  
Solar Observations ◽  
Solar Eruptions ◽  
Intensity Changes ◽  
Solar Ultraviolet

Abstract Solar flares have been linked to some of the most significant space weather hazards at Earth. These hazards, including radio blackouts and energetic particle events, can start just minutes after the flare onset. Therefore, it is of great importance to identify and predict flare events. In this paper we introduce the Detection and EUV Flare Tracking (DEFT) tool, which allows us to identify flare signatures and their precursors using high spatial and temporal resolution extreme-ultraviolet (EUV) solar observations. The unique advantage of DEFT is its ability to identify small but significant EUV intensity changes that may lead to solar eruptions. Furthermore, the tool can identify the location of the disturbances and distinguish events occurring at the same time in multiple locations. The algorithm analyzes high temporal cadence observations obtained from the Solar Ultraviolet Imager instrument aboard the GOES-R satellite. In a study of 61 flares of various magnitudes observed in 2017, the “main” EUV flare signatures (those closest in time to the X-ray start time) were identified on average 6 minutes early. The “precursor” EUV signatures (second-closest EUV signatures to the X-ray start time) appeared on average 14 minutes early. Our next goal is to develop an operational version of DEFT and to simulate and test its real-time use. A fully operational DEFT has the potential to significantly improve space weather forecast times.

scholarly journals COMMISSION 10: SOLAR ACTIVITY

2008 ◽  
Vol 4 (T27A) ◽  
pp. 79-103
Author(s):  
James A. Klimchuk ◽  
Lidia van Driel-Gesztelyi ◽  
Carolus J. Schrijver ◽  
Donald B. Melrose ◽  
Lyndsay Fletcher ◽  
...  
Keyword(s):  
Solar Activity ◽  
Coronal Mass Ejection ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Physics ◽  
Scientific Progress ◽  
Magnetic Clouds ◽  
Exciting Time ◽  
Mass Ejection ◽  
Coronal Dimming

Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into the following sections: Photosphere and chromosphere; Transition region; Corona and coronal heating; Coronal jets; flares; Coronal mass ejection initiation; Global coronal waves and shocks; Coronal dimming; The link between low coronal CME signatures and magnetic clouds; Coronal mass ejections in the heliosphere; and Coronal mass ejections and space weather. Primary authorship is indicated at the beginning of each section.

scholarly journals Solar Coronal Mass Ejections

1990 ◽  
Vol 140 ◽  
pp. 16-16
Author(s):  
A. J. Hundhausen ◽  
D. G. Sime ◽  
B. C. Low
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Interplanetary Space ◽  
Field Of View ◽  
Solar Activity Minimum ◽  
Eruptive Prominence ◽  
Activity Maximum ◽  
Mass Ejection

In addition to the more or less steady solar wind, the Sun also ejects mass in highly time dependent events taking place in the corona once every few days at solar activity minimum and as often as three times a day at solar activity maximum (Hundhausen 1988, Low 1986). These events involve large scale reconfiguration of the corona with an expulsion of some 1015g of ionized material into interplanetary space. The High Altitude Observatory (HAO) operates a groundbased internally occulted coronagraph at Mauna Loa, Hawaii, with a field of view of the corona from 1.2 to 2.2R⊙ in heliocentric distance, registering polarization brightness. A second instrument at the same site in Hawaii observes the solar limb in Hα emission to detect chromospheric material from the limb out to 1.5R⊙. HAO also operates an externally occulted coronagraph/polarimeter onboard the NASA Solar Maximum Mission Satellite (SMM) launched in 1980, capitalizing on the advantage of space with a field of view from 1.5 to 6R⊙ to cover the fainter outer corona. Coronal mass ejections involve magnetic field reconfiguration from high in the corona down to the base lying below 1.1R⊙. Important physical insights can be had when simultaneous observations by HAO's three instruments are put together with a common scale and orientation to reveal a mass ejection in the full extent of the solar atmosphere from the limb outward. Combined observations of two mass ejections are presented, one associated with an eruptive prominence and the the other associated with a flare. The significance of these two events is that in both cases, the mass ejection was in fully developed motion and had traveled high into the corona well before the onset of the associated prominence or flare eruption, pointing to an instability in the large scale coronal magnetic field as the underlying cause of the global reconfiguration.

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.

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