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Now showing items 1 - 16 of 16

  • Solar radio emission as a disturbance of aeronautical radionavigation

    Marque, Christophe   Klein, Karl-Ludwig   Monstein, Christian   Opgenoorth, Hermann   Pulkkinen, Antti   Buchert, Stephan   Krucker, Saem   Van Hoof, Rudiger   Thulesen, Peter  

    On November 4th, 2015 secondary air traffic control radar was strongly disturbed in Sweden and some other European countries. The disturbances occurred when the radar antennas were pointing at the Sun. In this paper, we show that the disturbances coincided with the time of peaks of an exceptionally strong (similar to 10(5) Solar Flux Units) solar radio burst in a relatively narrow frequency range around 1 GHz. This indicates that this radio burst is the most probable space weather candidate for explaining the radar disturbances. The dynamic radio spectrum shows that the high flux densities are not due to synchrotron emission of energetic electrons, but to coherent emission processes, which produce a large variety of rapidly varying short bursts (such as pulsations, fiber bursts, and zebra patterns). The radio burst occurs outside the impulsive phase of the associated flare, about 30 min after the soft X-ray peak, and it is temporarily associated with fast evolving activity occurring in strong solar magnetic fields. While the relationship with strong magnetic fields and the coherent spectral nature of the radio burst provide hints towards the physical processes which generate such disturbances, we have so far no means to forecast them. Well-calibrated monitoring instruments of whole Sun radio fluxes covering the UHF band could at least provide a real-time identification of the origin of such disturbances, which reports in the literature show to also affect GPS signal reception.
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  • Solar radio bursts as a tool for space weather forecasting

    Klein, Karl-Ludwig   Matamoros, Carolina Salas   Zucca, Pietro  

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  • Solar radio emission as a disturbance of aeronautical radionavigation

    Marqué, Christophe   Klein, Karl-Ludwig   Monstein, Christian   Opgenoorth, Hermann   Pulkkinen, Antti   Buchert, Stephan   Krucker, Säm   Van Hoof, Rudiger   Thulesen, Peter  

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  • Acceleration and Propagation of Solar Energetic Particles

    Klein, Karl-Ludwig   Dalla, Silvia  

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  • A method for the automated detection of solar radio bursts in dynamic spectra

    Salmane, Houssam   Weber, Rodolphe   Abed-Meraim, Karim   Klein, Karl-Ludwig   Bonnin, Xavier  

    The variability of the solar corona, including flares and coronal mass ejections, affects the space environment of the Earth (heating and ionization of the atmosphere, magnetic field disturbances, and bombardment by high-energy particles). Electromagnetic emissions are the first signatures of a solar eruptive event which by modifying the electron density in the ionosphere may affect airborne technology and radio communications systems. In this paper, we present a new method to detect automatically radio bursts using data from the Nancay Decametre Array (NDA) in the band 10 MHz-80 MHz. This method starts with eliminating unwanted signals (Radio-Frequency Interference, RFI and Calibration signals) by analyzing the dynamic spectrum of the signal recorded in time. Then, a gradient median filter is applied to smooth and to reduce the variability of the signal. After denoising the signal, an automated solar radio burst detection system is applied. This system is based on a sequential procedure with adaptive constant-false-alarm rate (CFAR like detector) aimed to extract the spectra of major solar bursts. To this end, a semi-automatic software package is also developed to create a data base of all possible events (type II, III, IV or other) that could be detected and used for our performance assessment.
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  • Catalogue of 55-80 MeV solar proton events extending through solar cycles 23 and 24

    Paassilta, Miikka   Raukunen, Osku   Vainio, Rami   Valtonen, Eino   Papaioannou, Athanasios   Siipola, Robert   Riihonen, Esa   Dierckxsens, Mark   Crosby, Norma   Malandraki, Olga   Heber, Bernd   Klein, Karl-Ludwig  

    We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the Solar and Heliospheric Observatory/the Energetic and Relativistic Nuclei and Electron experiment (SOHO/ERNE). In addition to ERNE proton and heavy ion observations, data from the Advanced Composition Explorer/Electron, Proton and Alpha Monitor (ACE/EPAM) (near-relativistic electrons), SOHO/EPHIN (Electron Proton Helium Instrument) (relativistic electrons), SOHO/LASCO (Large Angle and Spectrometric Coronagraph) (coronal mass ejections, CMEs) and Geostationary Operational Environmental Satellite (GOES) soft X-ray experiments are also considered and the associations between the particle and CME/X-ray events deduced to obtain a better understanding of each event. A total of 176 solar energetic particle (SEP) events have been identified as having occurred during the time period of interest; their onset and solar release times have been estimated using both velocity dispersion analysis (VDA) and time-shifting analysis (TSA) for protons, as well as TSA for near-relativistic electrons. Additionally, a brief statistical analysis was performed on the VDA and TSA results, as well as the X-rays and CMEs associated with the proton/electron events, both to test the viability of the VDA and to investigate possible differences between the two solar cycles. We find, in confirmation of a number of previous studies, that VDA results for protons that yield an apparent path length of 1 AU < s less than or similar to 3 AU seem to be useful, but those outside this range are probably unreliable, as evidenced by the anticorrelation between apparent path length and release time estimated from the X-ray activity. It also appears that even the first-arriving energetic protons apparently undergo significant pitch angle scattering in the interplanetary medium, with the resulting apparent path length being on average about twice the length of the spiral magnetic field. The analysis indicates an increase in high-energy SEP events originating from the far-eastern solar hemisphere; for instance, such an event with a well-established associated GOES flare has so far occurred three times during cycle 24 but possibly not at all during cycle 23. The generally lower level of solar activity during cycle 24, as opposed to cycle 23, has probably caused a significant decrease in total ambient pressure in the interplanetary space, leading to a larger proportion of SEP-associated halo-type CMEs. Taken together, these observations point to a qualitative difference between the two solar cycles.
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  • Exploring the potential of microwave diagnostics in SEP forecasting:The occurrence of SEP events

    Zucca, Pietro   Nunez, Marlon   Klein, Karl-Ludwig  

    Solar energetic particles (SEPs), especially protons and heavy ions, may be a space-weather hazard when they impact spacecraft and the terrestrial atmosphere. Forecasting schemes have been developed, which use earlier signatures of particle acceleration to predict the arrival of solar protons and ions in the space environment of the Earth. The UMASEP (University of MAlaga Solar particle Event Predictor) scheme forecasts the occurrence and the importance of an SEP event based on combined observations of soft X-rays, their time derivative and protons above 10 MeV at geosynchronous orbit. We explore the possibility to replace the derivative of the soft X-ray time history with the microwave time history in the UMASEP scheme. To this end we construct a continuous time series of observations for a 13-month period from December 2011 to December 2012 at two microwave frequencies, 4.995 and 8.8 GHz, using data from the four Radio Solar Telescope Network (RSTN) patrol stations of the US Air Force, and feed this time series to the UMASEP prediction scheme. During the selected period the Geostationary Operational Environmental Satellites (GOES) detected nine SEP events related to activity in the western solar hemisphere. We show that the SEP forecasting using microwaves has the same probability of detection as the method using soft X-rays, but no false alarm in the considered period, and a slightly increased warning time. A detailed analysis of the missed events is presented. We conclude that microwave patrol observations improve SEP forecasting schemes that employ soft X-rays. High-quality microwave data available in real time appear as a significant addition to our ability to predict SEP occurrence.
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  • The first SEPServer event catalogue similar to 68-MeV solar proton events observed at 1 AU in 1996-2010

    Vainio, Rami   Valtonen, Eino   Heber, Bernd   Malandraki, Olga E.   Papaioannou, Athanasios   Klein, Karl-Ludwig   Afanasiev, Alexander   Agueda, Neus   Aurass, Henry   Battarbee, Markus   Braune, Stephan   Droege, Wolfgang   Ganse, Urs   Hamadache, Clarisse   Heynderickx, Daniel   Huttunen-Heikinmaa, Kalle   Kiener, Juergen   Kilian, Patrick   Kopp, Andreas   Kouloumvakos, Athanasios   Maisala, Sami   Mishev, Alexander   Miteva, Rositsa   Nindos, Alexander   Oittinen, Tero   Raukunen, Osku   Riihonen, Esa   Rodriguez-Gasen, Rosa   Saloniemi, Oskari   Sanahuja, Blai   Scherer, Renate   Spanier, Felix   Tatischeff, Vincent   Tziotziou, Kostas   Usoskin, Ilya G.   Vilmer, Nicole  

    SEPServer is a three-year collaborative project funded by the seventh framework programme (FP7-SPACE) of the European Union. The objective of the project is to provide access to state-of-the-art observations and analysis tools for the scientific community on solar energetic particle (SEP) events and related electromagnetic (EM) emissions. The project will eventually lead to better understanding of the particle acceleration and transport processes at the Sun and in the inner heliosphere. These processes lead to SEP events that form one of the key elements of space weather. In this paper we present the first results from the systematic analysis work performed on the following datasets: SOHO/ERNE, SOHO/EPHIN, ACE/EPAM, Wind/WAVES and GOES X-rays. A catalogue of SEP events at 1 AU, with complete coverage over solar cycle 23, based on high-energy (similar to 68-MeV) protons from SOHO/ERNE and electron recordings of the events by SOHO/EPHIN and ACE/EPAM are presented. A total of 115 energetic particle events have been identified and analysed using velocity dispersion analysis (VDA) for protons and time-shifting analysis (TSA) for electrons and protons in order to infer the SEP release times at the Sun. EM observations during the times of the SEP event onset have been gathered and compared to the release time estimates of particles. Data from those events that occurred during the European day-time, i.e., those that also have observations from ground-based observatories included in SEPServer, are listed and a preliminary analysis of their associations is presented. We find that VDA results for protons can be a useful tool for the analysis of proton release times, but if the derived proton path length is out of a range of 1 AU < s less than or similar to 3 AU, the result of the analysis may be compromised, as indicated by the anti-correlation of the derived path length and release time delay from the associated X-ray flare. The average path length derived from VDA is about 1.9 times the nominal length of the spiral magnetic field line. This implies that the path length of first-arriving MeV to deka-MeV protons is affected by interplanetary scattering. TSA of near-relativistic electrons results in a release time that shows significant scatter with respect to the EM emissions but with a trend of being delayed more with increasing distance between the flare and the nominal footpoint of the Earth-connected field line.
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  • Solar Particle Acceleration Radiation and Kinetics (SPARK) A mission to understand the nature of particle acceleration

    Matthews, Sarah A.   Williams, David R.   Klein, Karl-Ludwig   Kontar, Eduard P.   Smith, David M.   Lagg, Andreas   Krucker, Sam   Hurford, Gordon J.   Vilmer, Nicole   MacKinnon, Alexander L.   Zharkova, Valentina V.   Fletcher, Lyndsay   Hannah, Iain G.   Browning, Philippa K.   Innes, Davina E.   Trottet, Gerard   Foullon, Clare   Nakariakov, Valery M.   Green, Lucie M.   Lamoureux, Herve   Forsyth, Colin   Walton, David M.   Mathioudakis, Mihalis   Gandorfer, Achim   Martinez-Pillet, Valentin   Limousin, Olivier   Verwichte, Erwin   Dalla, Silvia   Mann, Gottfried   Aurass, Henri   Neukirch, Thomas  

    Energetic particles are critical components of plasma populations found throughout the universe. In many cases particles are accelerated to relativistic energies and represent a substantial fraction of the total energy of the system, thus requiring extremely efficient acceleration processes. The production of accelerated particles also appears coupled to magnetic field evolution in astrophysical plasmas through the turbulent magnetic fields produced by diffusive shock acceleration. Particle acceleration is thus a key component in helping to understand the origin and evolution of magnetic structures in, e.g. galaxies. The proximity of the Sun and the range of high-resolution diagnostics available within the solar atmosphere offers unique opportunities to study the processes involved in particle acceleration through the use of a combination of remote sensing observations of the radiative signatures of accelerated particles, and of their plasma and magnetic environment. The SPARK concept targets the broad range of energy, spatial and temporal scales over which particle acceleration occurs in the solar atmosphere, in order to determine how and where energetic particles are accelerated. SPARK combines highly complementary imaging and spectroscopic observations of radiation from energetic electrons, protons and ions set in their plasma and magnetic context. The payload comprises focusing-optics X-ray imaging covering the range from 1 to 60 keV; indirect HXR imaging and spectroscopy from 5 to 200 keV, gamma-ray spectroscopic imaging with high-resolution LaBr3 scintillators, and photometry and source localisation at far-infrared wavelengths. The plasma environment of the regions of acceleration and interaction will be probed using soft X-ray imaging of the corona and vector magnetography of the photosphere and chromosphere. SPARK is designed for solar research. However, in addition it will be able to provide exciting new insights into the origin of particle acceleration in other regimes, including terrestrial gamma-ray flashes (TGF), the origin of gamma-ray bursts, and the possible existence of axions.
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  • Comprehensive Characterization of Solar Eruptions with Remote and In-Situ Observations, and Modeling: The Major Solar Events on 4 November 2015

    Cairns, Iver H.   Kozarev, Kamen A.   Nitta, Nariaki V.   Agueda, Neus   Battarbee, Markus   Carley, Eoin P.   Dresing, Nina   Gómez-Herrero, Raúl   Klein, Karl-Ludwig   Lario, David   Pomoell, Jens   Salas-Matamoros, Carolina   Veronig, Astrid M.   Li, Bo   McCauley, Patrick  

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  • Book Review: Karl-Ludwig Klein (ed.), Energy Conversion and Particle Acceleration in the Solar Corana, Lecture Notes in Physics

    M. Ya Marov   C. D. Garmany   André Heck   A. Schadee and D. McNally   et al.  

    Book Review: Karl-Ludwig Klein (ed.), Energy Conversion and Particle Acceleration in the Solar Corana, Lecture Notes in Physics
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  • Book Review: Karl-Ludwig Klein (ed.), Energy Conversion and Particle Acceleration in the Solar Corana, Lecture Notes in Physics

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  • Book Review: Karl-Ludwig Klein (ed.), Energy Conversion and Particle Acceleration in the Solar Corana, Lecture Notes in Physics

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  • [Lecture Notes in Physics] Energy Conversion and Particle Acceleration in the Solar Corona Volume 612 || Particle Acceleration by Magnetic Reconnection

    Klein, Karl-Ludwig  

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  • [Lecture Notes in Physics] Energy Conversion and Particle Acceleration in the Solar Corona Volume 612 || Particle Acceleration Processes in Cosmic Plasmas

    Klein, Karl-Ludwig  

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  • [AIP High-energy solar phenomena—A new era of spacecraft measurements - Waterville Valley, New Hampshire (USA) (Mar 1993)] AIP Conference Proceedings - Energetic electron injection into the high corona during the gradual phase of flares: Evidence against acceleration by a large scale shock

    Klein, Karl-Ludwig   Trottet, Ge?rard  

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