scholarly journals Relation between coronal type II bursts, associated flares and CMEs

2008 ◽  
Vol 4 (S257) ◽  
pp. 299-301 ◽  
Author(s):  
George Pothitakis ◽  
Panagiota Preka-Papadema ◽  
Xenophon Moussas ◽  
Constantine Caroubalos ◽  
Constantine Alissandrakis ◽  
...  
Keyword(s):  
Blast Wave ◽  
Radio Burst ◽  
Geophysical Data ◽  
Radio Bursts ◽  
Type Ii ◽  
Complex Events ◽  
Type Ii Bursts

AbstractWe study a sample of complex events; each includes a coronal type II burst, accompanied by a GOES SXR flare and LASCO CME. The radio bursts were recorded by the ARTEMIS-IV radio spectrograph (100-650 MHz range); the GOES SXR flares and SOHO/LASCO CMEs, were obtained from the Solar Geophysical Data (SGD) and the LASCO lists respectively. The radio burst-flare-CME characteristics were compared and two groups of events with similar behavior were isolated. In the first the type II shock exciter appears to be a flare blast wave propagating in the wake of a CME. In the second the type II burst appears CME initiated though it is not always clear if it is driven by the bow or the flanks of the CME or if it is a reconnection shock.

scholarly journals Coronal shocks associated with CMEs and flares and their space weather consequences

2008 ◽  
Vol 4 (S257) ◽  
pp. 61-63
Author(s):  
Marina Laskari ◽  
Panagiota Preka-Papadema ◽  
Constantine Caroubalos ◽  
George Pothitakis ◽  
Xenophon Moussas ◽  
...  
Keyword(s):  
Solar Wind ◽  
Geomagnetic Activity ◽  
Space Weather ◽  
Geophysical Data ◽  
Radio Bursts ◽  
Type Ii ◽  
Geomagnetic Indices ◽  
Complex Events ◽  
Solar Wind Parameters ◽  
Solar Energetic Events

AbstractWe study the geoeffectiveness of a sample of complex events; each includes a coronal type II burst, accompanied by a GOES SXR flare and LASCO CME. The radio bursts were recorded by the ARTEMIS-IV radio spectrograph, in the 100-650 MHz range; the GOES SXR flares and SOHO/LASCO CMEs, were obtained from the Solar Geophysical Data (SGD) and the LASCO catalogue respectively. These are compared with changes of solar wind parameters and geomagnetic indices in order to establish a relationship between solar energetic events and their effects on geomagnetic activity.

scholarly journals Analyzing the propagation of EUV waves and their connection with type II radio bursts by combining numerical simulations and multi-instrument observations

2020 ◽  
Vol 644 ◽  
pp. A90
Author(s):  
A. Koukras ◽  
C. Marqué ◽  
C. Downs ◽  
L. Dolla
Keyword(s):  
Magnetic Field ◽  
Wave Front ◽  
Ray Tracing ◽  
Radio Burst ◽  
Radio Bursts ◽  
Type Ii ◽  
Fast Mode ◽  
Type Ii Radio Bursts ◽  
The Magnetic Field ◽  
Burst Emission

Context. EUV (EIT) waves are wavelike disturbances of enhanced extreme ultraviolet (EUV) emission that propagate away from an eruptive active region across the solar disk. Recent years have seen much debate over their nature, with three main interpretations: the fast-mode magneto-hydrodynamic (MHD) wave, the apparent wave (reconfiguration of the magnetic field), and the hybrid wave (combination of the previous two). Aims. By studying the kinematics of EUV waves and their connection with type II radio bursts, we aim to examine the capability of the fast-mode interpretation to explain the observations, and to constrain the source locations of the type II radio burst emission. Methods. We propagate a fast-mode MHD wave numerically using a ray-tracing method and the WKB (Wentzel-Kramers-Brillouin) approximation. The wave is propagated in a static corona output by a global 3D MHD Coronal Model, which provides density, temperature, and Alfvén speed in the undisturbed coronal medium (before the eruption). We then compare the propagation of the computed wave front with the observed wave in EUV images (PROBA2/SWAP, SDO/AIA). Lastly, we use the frequency drift of the type II radio bursts to track the propagating shock wave, compare it with the simulated wave front at the same instant, and identify the wave vectors that best match the plasma density deduced from the radio emission. We apply this methodology for two EUV waves observed during SOL2017-04-03T14:20:00 and SOL2017-09-12T07:25:00. Results. The simulated wave front displays a good qualitative match with the observations for both events. Type II radio burst emission sources are tracked on the wave front all along its propagation. The wave vectors at the ray-path points that are characterized as sources of the type II radio burst emission are quasi-perpendicular to the magnetic field. Conclusions. We show that a simple ray-tracing model of the EUV wave is able to reproduce the observations and to provide insight into the physics of such waves. We provide supporting evidence that they are likely fast-mode MHD waves. We also narrow down the source region of the radio burst emission and show that different parts of the wave front are responsible for the type II radio burst emission at different times of the eruptive event.

scholarly journals On Split-Band Structure in Type II Radio Bursts from the Sun

1974 ◽  
Vol 57 ◽  
pp. 389-393 ◽  
Author(s):  
S. F. Smerd ◽  
K. V. Sheridan ◽  
R. T. Stewart
Keyword(s):  
Band Structure ◽  
The Sun ◽  
Radio Bursts ◽  
Type Ii ◽  
Band Splitting ◽  
Measured Amount ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Split Band

(Astrophys. Letters). The measured amount of band-splitting, Δf, in the spectra of nine harmonic type II bursts is illustrated in Figure 1. Here, as in previous, smaller samples (Roberts, 1959; Maxwell and Thompson, 1962; Weiss, 1965) Δf is found to increase with frequency, f.

On the Possibility of Radio Emission from Quasi-parallel and Quasi-perpendicular Propagation of Shocks

2000 ◽  
Vol 179 ◽  
pp. 259-262
Author(s):  
A. Shanmugaraju ◽  
S. Umapathy
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Radio Bursts ◽  
Type Ii ◽  
Simple Analysis ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts

AbstractA set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. A simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.

Shock Drift Acceleration and Type II Solar Radio Bursts

1994 ◽  
Vol 11 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Arthur G. Street ◽  
Lewis Ball ◽  
D. B. Melrose
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Shock Front ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Ii Bursts ◽  
Herringbone Structure ◽  
The Magnetic Field

AbstractShock drift acceleration of the electrons which produce herringbone structure in type II bursts is considered. A non-coplanar component of the magnetic field within the shock front and an electric field across the shock are taken into account. A quantitative difficulty with shock drift acceleration is identified, and possible ways of overcoming the difficulty are outlined.

scholarly journals Type II Bursts of Different Subclasses Associated to Transients and Mass Ejection in the Higher Corona

1996 ◽  
Vol 154 ◽  
pp. 203-207
Author(s):  
H.W. Urbarz
Keyword(s):  
Shock Front ◽  
Geophysical Data ◽  
Type Ii ◽  
Type Ii Bursts ◽  
Mass Ejection ◽  
The Relationship

AbstractThe list of mass ejections published in Solar Geophysical Data during the period of Jan. 1981 to Oct. 1987 contains about 1300 Surges, Sprays and Type II bursts. The relationship between the mass ejection events and the shock front events is investigated by means of correlation of time and position. The result shows that type II bursts start as frequently after the mass ejections as prior to them.

scholarly journals Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era

2008 ◽  
Vol 26 (10) ◽  
pp. 3033-3047 ◽  
Author(s):  
N. Gopalswamy ◽  
S. Yashiro ◽  
S. Akiyama ◽  
P. Mäkelä ◽  
H. Xie ◽  
...  
Keyword(s):  
Coronal Mass Ejections ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Western Hemisphere ◽  
Radio Bursts ◽  
Type Ii ◽  
Association Rate ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Weak Shocks

Abstract. Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy). If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH) wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event.

AUTOMATIC RECOGNITION OF CORONAL TYPE II RADIO BURSTS: THE AUTOMATED RADIO BURST IDENTIFICATION SYSTEM METHOD AND FIRST OBSERVATIONS

2010 ◽  
Vol 710 (1) ◽  
pp. L58-L62 ◽  
Author(s):  
Vasili V. Lobzin ◽  
Iver H. Cairns ◽  
Peter A. Robinson ◽  
Graham Steward ◽  
Garth Patterson
Keyword(s):  
Radio Burst ◽  
Automatic Recognition ◽  
Identification System ◽  
Radio Bursts ◽  
Type Ii ◽  
System Method ◽  
Type Ii Radio Bursts

Using supervised machine learning to automatically detect type II and III solar radio bursts

2020 ◽  
Author(s):  
Eoin Carley
Keyword(s):  
Machine Learning ◽  
Radio Burst ◽  
Solar Radio ◽  
Machine Learning Algorithms ◽  
Supervised Machine Learning ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Dynamic Spectra

&lt;p&gt;Solar flares are often associated with high-intensity radio emission known as `solar radio bursts' (SRBs). SRBs are generally observed in dynamic spectra and have five major spectral classes, labelled type I to type V depending on their shape and extent in frequency and time. Due to their morphological complexity, a challenge in solar radio physics is the automatic detection and classification of such radio bursts. Classification of SRBs has become necessary in recent years due to large data rates (3 Gb/s) generated by advanced radio telescopes such as the Low Frequency Array (LOFAR). Here we test the ability of several supervised machine learning algorithms to automatically classify type II and type III solar radio bursts. We test the detection accuracy of support vector machines (SVM), random forest (RF), as well as an implementation of transfer learning of the Inception and YOLO convolutional neural networks (CNNs). The training data was assembled from type II and III bursts observed by the Radio Solar Telescope Network (RSTN) from 1996 to 2018, supplemented by type II and III radio burst simulations. The CNNs were the best performers, often exceeding &gt;90% accuracy on the validation set, with YOLO having the ability to perform radio burst burst localisation in dynamic spectra. This shows that machine learning algorithms (in particular CNNs) are capable of SRB classification, and we conclude by discussing future plans for the implementation of a CNN in the LOFAR for Space Weather (LOFAR4SW) data-stream pipelines.&lt;/p&gt;

Type II Solar Radio Bursts Observed with the Culgoora Radioheliograph during a Flare on 17 June 1968

1968 ◽  
Vol 1 (4) ◽  
pp. 141-142 ◽  
Author(s):  
K. Kai ◽  
D. J. McLean
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Flare Event ◽  
Type Iv ◽  
Type Ii Bursts

On 17 June 1968 we observed a flare event with the 80 MHz Culgoora radioheliograph consisting of a sequence of two type II bursts followed by enhanced emission possibly of type IV. In this paper we shall attempt to summarize some ofthe profuse data collected by the radioheliograph during this event and relate it to data from the radiospectrograph and Hα films of the associated flare (the Hα films were kindly made available by the Division of Physics, CSIRO).

Sign in / Sign up

Export Citation Format

Share Document