Session 9 - The role of solar radio observations in Space Weather science
Jasmina Magdalenic (ROB), Alexander Nindos (Univ. of Ioannina), Manuela Temmer (Uni-Graz)
Wednesday 29/11, 9:45 - 13:00
solar radio emission, eruptive events, space weather
Solar eruptive events such as coronal mass ejections (CMEs) and flares, and associated shock waves are the most frequent drivers of disturbed space weather conditions. Since, both flares and CMEs emit radio emission, solar radio observations bring an important additional information to studies of eruptive events and correspondingly to space weather studies. Radio observations bring information about the energy release, the configuration of flare-CME source regions including the position of open magnetic field lines and their connectivity to the Earth, about the particle acceleration and transport, and the origin of solar energetic particle (SEP) events. Radio observations are also unique means of tracking CME-driven shock waves all the way from the low corona through the inner heliosphere, and they can provide information on the ambient coronal parameters.
This session aims to promote the importance of radio observations in space weather studies and introduce them to the wider heliospheric/space weather communities. The session is open to all space weather studies that exploit solar radio observations and to all studies of radio observations relevant to space weather.
From Monday noon to Wednesday morningTalks
Wednesday November 29, 09:45 - 11:00, Mercator
Wednesday November 29, 11:45 - 13:00, MercatorClick here to toggle abstract display in the schedule
Talks : Time scheduleWednesday November 29, 09:45 - 11:00, Mercator
Wednesday November 29, 11:45 - 13:00, Mercator
|09:45||Radio observations of solar flare electron acceleration||Battaglia, M et al.||Invited Oral|
| ||Marina Battaglia|
| ||University of Applied Sciences and Arts Northwestern Switzerland|
| ||Solar flares are one of the main drivers of space weather and are often linked to CME’s. They efficiently release large amounts of magnetic energy in seconds to minutes and convert it into accelerated particles (electrons and ions) and heating of all layers of the solar atmosphere. The signatures of accelerated electrons are most readily observed in radio and X-ray wavelengths. Radio observations of solar flares provide invaluable information on the acceleration region, as well as electron propagation close to the Sun and away from the Sun. Thus they are crucial for our understanding of solar flares. I will discuss how radio observations, in combination with X-ray data and observations at other wavelengths, can be used to study flare accelerated electrons and present recent highlights from studies using data from observatories such as the VLA and the Nancay Radio Heliograph.|
|10:05||Study of the signature of a coronal shock with LOFAR and multi-viewpoint observations, space weather implications.||Zucca, P et al.||Oral|
| ||Pietro Zucca, Diana Morosan, Peter T. Gallagher, Richard Fallows, Alexis Rouillard, Jasmina Magdalenic, Christian Vocks, Christophe Marqué, Karl-Ludwig Klein, and Gottfried Mann |
| ||Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, The Netherlands; Astrophysics Research Group, School of Physics, Trinity College Dublin, 2 Dublin, Ireland; Institut de Recherche en Astrophysique et Planetologie, 9 Ave. du Colonel Roche 31028, Toulouse Cedex 4, France; Solar-Terrestrial Center of Excellence, SIDC, Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Brussels, Belgium; Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany; Observatoire de Paris, LESIA, Paris, France|
| ||Type II radio bursts are evidence of shocks in the solar atmosphere emitting radio waves ranging from metric to kilometric lengths. These shocks may be associated with coronal mass ejections (CMEs) reaching super-Alfv enic speeds. These radio signature are key to understand the relationship between CMEs and shock waves and to define the input for space weather modelling and to forecast the arrival time of shocks and CMEs on Earth.
Radio imaging of the decameter wavelengths is now possible with the Low Frequency Array (LOFAR), opening a new radio window to study coronal radio shocks leaving the inner solar corona and entering the interplanetary medium and understand their association with CMEs.
Here, we study a coronal shock associated with a CME and type II radio burst to determine the location where the shock is triggered in relation to the propagating CME, the ambient medium Alfvén speed and the orientation of the coronal magnetic field. The type II shock imaging and spectra were obtained using 91 simultaneous tied-array beams of LOFAR while the CME was observed and triangulated using multi-viewpoint observations including the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO).
Using the tied array beam observing mode of LOFAR we were able to locate the type II radio shock position between 45 and 75 MHz and relate it to the expanding flank of a CME leaving the inner corona. With the key help of the multi-viewpoint observations, the radio emission associated with the type II burst was found to be located at the flank of the CME in a region where the mach number is between 1.5 to 2.0 and the shock geometry is quasi-perpendicular. These parameters will contribute to the modelling of the propagation of shocks and CMEs for space weatherer purposes.|
|10:20||Coronal mass ejections and their interplanetary radio signatures||Pohjolainen, S et al.||Invited Oral|
| ||Silja Pohjolainen|
| ||Tuorla Observatory, University of Turku, Finland|
| ||Coronal mass ejections (CMEs) from the Sun can create a variety of radio signatures during their propagation in the interplanetary medium, and identifying these can help to predict shock arrivals and geomagnetic storms. During periods of high solar activity several CMEs can be launched close to each other, both spatially and temporally, and therefore interactions between the masses and/or shocks can occur. Changes in the propagation velocities and plasma densities, during and after merging of the plasma structures, can sometimes be observed directly in the radio emission. In some cases there may also be indirect evidence of the CME and shock wave propagation, as later-accelerated particle beams are observed to stop near the CME leading front, even if the shock itself leaves no trace in the radio dynamic spectrum. The source of solar energetic particles (SEPs) may also be linked to the evolution of the CME structures. The 3D-view provided by the radio instruments onboard STEREO A, STEREO B, and Wind spacecrafts - even without real radio imaging - has helped us to understand how the features observed at decameter-hectometer waves are associated with the propagating disturbances in the interplanetary space.|
|10:40||Multi-viewpoint Observations of a Widely Distributed Solar Energetic Particle Event: the Role of EUV Waves and Shock Signatures||Nindos, A et al.||Oral|
| ||Alexander Nindos, Athanasios Kouloumvakos, Spiros Patsourakos, Angelos Vourlidas, Anastasios Anastasiadis, Alexander Hillaris, Ingmar Sandberg|
| ||Physics Department, University of Ioannina, Greece; The Johns Hopkins University, Applied Physics Laboratory, United States; Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Greece; Department of Physics, University of Athens, Greece|
| ||On 2012 March 7, two large eruptive events occurred in the same active region within 1 hr from each other. Each consisted of an X-class flare, a coronal mass ejection (CME), an extreme-ultraviolet (EUV) wave, and a shock wave. The eruptions gave rise to a major solar energetic particle (SEP) event observed at widely separated (∼120 degrees) points in the heliosphere. From multi-viewpoint energetic proton recordings we determine the proton release times at STEREO B and A (STB, STA) and the first Lagrange point (L1) of the Sun–Earth system. Using EUV and white-light data, we determine the evolution of the EUV waves in the low corona and reconstruct the global structure and kinematics of the first CME's shock, respectively. We compare the energetic proton release time at each spacecraft with the EUV waves' arrival times at the magnetically connected regions and the timing and location of the CME shock. We find that the first flare/CME is responsible for the SEP event at all three locations. The proton release at STB is consistent with arrival of the EUV wave and CME shock at the STB footpoint. The proton release time at L1 was significantly delayed compared to STB. Three-dimensional modeling of the CME shock shows that the particle release at L1 is consistent with the timing and location of the shock's western flank. This indicates that at L1 the proton release did not occur in low corona but farther away from the Sun. However, the extent of the CME shock fails to explain the SEP event observed at STA. A transport process or a significantly distorted interplanetary magnetic field may be responsible.|
|11:45||Simultaneous Near-Sun Observations of a Moving Type IV Radio Burst and the Associated White-Light Coronal Mass Ejection||Krishnan, H et al.||Oral|
| ||K. Hariharan, R. Ramesh, C. Kathiravan, T.J. Wang|
| ||National Centre for Radio Astrophysics; Indian Institute of Astrophysics; Department of Physics, The Catholic University of America and NASA Goddard Space Flight Center|
| ||We present rare contemporaneous low-frequency (< 100 MHz) imaging, spectral, and polarimetric observations of a moving type IV radio burst that had close spatio-temporal association with a white-light coronal mass ejection (CME) near the Sun. We estimate the electron density near the burst region from white-light coronagraph polarized brightness (pB) images of the CME as well as the two-dimensional radio imaging observations of the
thermal free-free emission at a typical radio frequency such as 80 MHz. We analyze the burst properties such as the degree of circular polarization, the spectral index, and fine structures using the radio polarimeter and the radio spectral observations. The obtained results suggest that second harmonic plasma emission from the enhanced electron density in the leading edge of the CME is the cause of the radio burst. We determine the strength of the coronal magnetic field (B) for the first time based on this interpretation. The estimated value
(B ≈ 1 gauss) in the CME leading edge at a heliocentric distance of ≈ 2.2 R agrees well with the similar B values reported earlier based on other types of observations.|
|12:00||Solar radio bursts as space weather hazard and as a space weather prediction tool||Klein, K et al.||Invited Oral|
| ||Karl-Ludwig Klein|
| ||LESIA, Observatoire de Paris and CNRS|
| ||Solar flares and the liftoff of coronal mass ejections (CMEs) may be accompanied by the acceleration of electrons to largely suprathermal energies. These electrons emit radio waves through the gyrosynchrotron process or through collective plasma emission. The radio emission is a potential space weather hazard, when it is intense enough to compete with radio signals used for communication and navigation. It may also be used as a space weather prediction tool. In this presentation both aspects of radio emission will be addressed. An introductory overview of solar radio emission and its relationship with flares will be given. This includes the illustration of a major solar radio burst on 2015 November 04, which was apparently the source of perturbations of air traffic control radar in Sweden. Then two studies will be summarised where radio bursts at frequencies of a few GHz are used for the prediction of the arrival of CMEs and solar energetic particles (SEP) at Earth.
This work is supported by the ANR/ASTRID/DGA project ORME (Observations Radio astronomiques pour la Météorologie de l’espace, contract No. ANR-14-ASTR-0027), by the HESPERIA project, funded by the European Union’s Horizon 2020 research and innovation program under grant agreement No 637324, and by the Centre National d’Etudes Spatiales (CNES).
|12:20||The Radio Telescope LOFAR as a Novel Tool for Space Weather||Mann, G et al.||Oral|
| ||Gottfried Mann and Christian Vocks|
| ||Leibniz-Institut fuer Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany|
| ||Since 2009, LOFAR (Low Frequency Array) is operating as a novel radio telescope working in the frequency range 10-250 MHz. LOFAR was originally designed by ASTRON in the Netherlands. Presently, it consists of 24 core and 14 remote stations in the Netherlands and additionally 13 international ones distributed over central Europe. The radio signals of each individual station are transferred via a high data rate link (10 Gbit/s) to Groningen, where they are correlated to radio maps of the sky by means of a super-computer. The science with LOFAR is organized in terms of key science projects. One of them is called “Solar Physics and Space Weather with LOFAR”.
LOFAR is able to observe the solar radio radiation in the low (10-90 MHz) and high (110-250 MHz) band range. Therefore, LOFAR is a highly interesting tool for observing the solar activity. LOFAR really works as a dynamic spectroscopic imager of the Sun as demonstrated by the solar event on June 23, 2012. With LOFAR fast electron motions can be tracked in the solar corona. Hence, LOFAR is highly appropriate as a tool for Space Weather, especially in the low band range, since the radio radiation in this range is emitted in the outer corona, where the sources of Space Weather, as e.g. coronal mass ejections and shock waves, are located.
In the next few years, an upgrade of LOFAR called LOFAR2.0 is intended. For solar observations LOFAR2.0 would allow to observe the Sun simultaneously in both the low and high frequency band. LOFAR2.0 offers the possibility to create routinely radio images of the Sun and simultaneously dynamic radio spectra. That would be very interesting for a regular monitoring of the solar activity in the radio range. That would deliver information on the solar activity in addition to observations of the Sun in other spectral ranges. Thus, LOFAR2.0 will be a unique tool for Space Weather science.
The talk will be presented on behalf of all members of the solar and space weather key science project.|
|12:35||3D-MHD Modeling Using Interplanetary Scintillation (IPS) Observations||Jackson, B et al.||Oral|
| ||Bernard V. Jackson, Hsiu-Shan Yu, P. Paul Hick, Andrew Buffington, Mario M. Bisi, Dusan Odstrcil, Tae. Kim, Nick Pogorelov, Munetoshi Tokumaru, Jaehun Kim, and Jongyeon Yun|
| ||University of California, San Diego, United States; Science & Technology Facilities Council - Rutherford Appleton Laboratory, United Kingdom; George Mason University, Fairfax, Virginia, and NASA-Goddard Spaceflight Center, United States; Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville (UAH), Huntsville, AL, United States; Institute for Space-Earth Environmental Research, Nagoya University, Japan; Korean Space Weather Center, South Korea, National Radio Research Agency, South Korea; Space Environment Laboratory, Seoul, South Korea|
| ||The University of California, San Diego has developed an iterative remote-sensing time-dependent three-dimensional (3D) reconstruction technique which provides volumetric maps of density, velocity, and magnetic field. We have applied this technique in near real time for over 15 years with a kinematic model approximation to fit data from ground-based interplanetary scintillation (IPS) observations. Our modeling concept extends volumetric data from an inner boundary placed above the Alfvén surface out to the inner heliosphere. We now use this technique to drive 3D-MHD models at their inner boundary and generate output 3D data files that can be fit to remotely-sensed observations (in this case IPS observations), and iterated. To facilitate this process, we have developed a traceback from input 3D-MHD volumes to yield an updated boundary in density, temperature, and velocity, which also includes magnetic-field components. Here we will show examples of this analysis using the ENLIL 3D-MHD and the University of Alabama Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS) heliospheric codes.|
|12:50||The Worldwide Interplanetary Scintillation (IPS) Stations (WIPSS) Network: Initial Results from the October 2016 Space-Weather Campaign||Bisi, M et al.||Oral|
| ||Mario M. Bisi, Bernard V. Jackson, Richard A. Fallows, Munetoshi Tokumaru, Ernesto Aguilar-Rodriguez[5,6,7], J. Americo Gonzalez-Esparza[5,6,7], Julio C. Mejia-Ambriz[5,6,7], Igor Chashei, Sergey Tyul’bashev, John Morgan, Periasamy K. Manoharan, Oyuki Chang, Hsiu-Shan Yu, Dusan Odstrcil[11,12], David Barnes, and Biagio Forte.|
| ||STFC-RAL Space, UK; CASS-UCSD, CA, USA; ASTRON, NL; ISEE, Nagoya University, Japan; SCiESMEX, MX; MEXART, MX; UNAM, MX; Pushchino Radio Observatory, Russia; Curtin University, WA, Australia; TIFR, Ooty, India; GMU, VA, USA; NASA GSFC, MD, USA; University of Bath, UK.|
| ||Observations of interplanetary scintillation (IPS) are used to provide a global measure of velocity and density as well as indications of changes in the plasma and magnetic-field rotations along each observational line of sight. There exists (since late-2014) a well-defined IPS Common Data Format (IPSCDFv1.0 – with IPSCDFv1.1 rollout expected in mid-/late-2017) which has implemented by much of the global IPS space-weather community. The new Worldwide IPS Stations (WIPSS) Network aims to bring together the worldwide real-time-capable IPS observatories, as well as those used on a campaign-only basis, with well-developed and tested analyses techniques. If observations of IPS are formally inverted into a three-dimensional (3-D) tomographic reconstruction (such as using the University of California, San Diego – UCSD – kinematic model and reconstruction technique), then source-surface magnetic fields can be propagated out to the Earth (and beyond) as well as in-situ data also being incorporated into the reconstruction. By combining IPS data from multiple observing locations, we can increase both the spatial and temporal coverage across the whole of the inner heliosphere. Currently, the tomography has been undertaken near-operationally since around 2000 using IPS data only from the Institute for Space-Earth Environmental Research (ISEE) (formerly STELab/STEL), Nagoya University, Japan, and has been used scientifically since the 1990s. During October 2016, a unique opportunity arose whereby the European-based LOw Frequency ARray (LOFAR) novel “software” radio telescope was used to make nearly four weeks of continuous observations of IPS as a heliospheric space-weather pilot campaign. In addition, the Murchison Widefield Array (MWA) in Western Australia was also used for imaging observations of IPS during much of the same period. This LOFAR-WIPSS-MWA campaign was expanded into a true global effort to include observations of IPS from many other IPS-capable/IPS-dedicated WIPSS Network systems. IPS data from LOFAR, ISEE, MEXART, and where practicable, other WIPSS Network and/or the MWA are used in this study from which we present some initial findings from both a scientific and operational point of view.|
|1||Constraining the solar coronal magnetic field strength using split-band type II radio burst observations||Krishnan, H et al.||e-Poster|
| ||P. Kishore, R. Ramesh, K. Hariharan, C. Kathiravan, and N. Gopalswamy|
| ||Indian Institute of Astrophysics; National Centre for Radio Astrophysics; Code 671, Solar Physics Laboratory, NASA/GSFC|
| ||We report on low-frequency radio (85–35 MHz) spectral observations of four different type II radio bursts, which
exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely
associated with a white-light coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic
field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the location of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the de-projected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the de-projected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa|
|2||The Dawn of Solar Physics and Space Weather studies with the Sardinia Radio Telescope: Imaging of the Chromosphere in the Millimeter Range, a Feasibility Study ||Pellizzoni, A et al.||e-Poster|
| ||Alberto Pellizzoni, Noemi Iacolina, Alessandro Navarrini, Giuseppe Valente, Elise Egron, Mauro Messerotti|
| ||INAF - Osservatorio Astronomico di Cagliari; Italian Space Agency (ASI); INAF - Osservatorio Astronomico di Trieste|
| ||The Sardinia Radio Telescope (SRT, www.srt.inaf.it) is a 64-m diameter radio telescope with Gregorian configuration located on the Sardinia island (Italy), and is designed to observe in the 0.3-116 GHz frequency range from different focal positions (primary, Gregorian and Beam waveguides). At present, receivers are available for observers in the 0.3-26.5 GHz range including a K-band seven-beam dual-polarization cryogenic receiver at the Gregorian focus. The SRT offers advanced technology with the implementation of an active surface on the primary mirror, allowing to compensate the gravitational deformations of the backup structure and to flatten the antenna efficiency versus elevation resulting in optimal spectral-polarimetric imaging performances.
In the perspective of the implementation of a new Q-band multi-feed cryogenic receiver (33 - 50 GHz) for the Gregorian focus, full imaging of the solar chromosphere can be obtained through on-the-fly scans in a few minute exposure with an angular resolution of less than 30 arcsec. Mapping the brightness temperature of the radio free-free emission in the millimeter range is an effective tool for characterising the vertical structure of the solar chromosphere. This application will be suitable for solar physics studies (e.g. measurement of the brightness temperature of the the sunspot umbra) and will contribute to space weather monitoring networks.
Early solar imaging tests related to this project will be performed by mid 2018 in K-band, after thermal and electrical assessment of the SRT set-up, in order to prevent structural damaging and saturation of the receivers during solar exposures. |
|3||Radio observations as input for the ESPERTA model to forecast moderate-to-extreme solar proton events||Laurenza, M et al.||p-Poster|
| ||Monica Laurenza, Tommaso Alberti, and Edward W. Cliver|
| ||INAF-IAPS, Via del Fosso del Cavaliere, 100, I-00133, Roma, Italy; Dipartimento di Fisica, Università della Calabria, Ponte P. Bucci, Cubo 31C, 87036, Rende (CS) Italy; National Solar Observatory, 3665 Discovery Drive, Boulder, CO, 80303, USA|
| ||The ESPERTA (Empirical model for Solar Proton Event Real Time Alert) proton event forecast tool was developed to predict solar proton events (SPEs) with peak intensity >10 pfu (i.e., ≥S1 events, where S1 refer to minor storms on the NOAA Solar Radiation Storms scale), by using three input parameters for ≥M2 SXR flares: the heliographic longitude, the soft X-ray (SXR) fluence and the ~1 MHz radio fluence as indicator of particle escape as well as a measure of flare size (which is usually ascribed solely to the SXR fluence). The evaluation of ESPERTA provided a Probability of Detection (POD) of 62% for all the >10 MeV events, from 1995-2014, with a false alarm rate (FAR) of 39% and a median (minimum) warning time of ~4.8 (0.4) h. Moreover, the radio fluence was found to be a more efficient parameter in distinguishing between the SEP associated events from the not associated ones. In addition, the ESPERTA model was modified to predict only >100 pfu (i.e., ≥S2 events, moderate to extreme) proton events, which produce both biological and space operations impacts and increased effects on HF propagation in the polar regions. The obtained verification measures are the following: POD of 79% (41/52) and a FAR of 23% (12/53) for the 1995-2014 interval with a median (minimum) warning time of ~1.5 (~0.2) h based on predictions made at the time of the S1 threshold crossing. Finally, results showed that the median radio fluence for flares associated with ≥S2 events is generally increased of about one order of magnitude with respect to those associated with S1 events.|
|4||Impact of the 2015 November 04 solar radio burst on Air Traffic operations||Marqué, C et al.||p-Poster|
| ||C. Marqué, K. -L. Klein, C. Monstein, H. Opgenoorth, S. Buchert, A. Pulkkinen, S. Krucker, R. Van Hoof, P. Thulesen|
| ||Royal Observatory of Belgium; Observatoire de Paris; ETH Zurich; SSI; NASA; FHNW; Belgocontrol; Air Greenland|
| ||We investigate the reasons of air traffic disturbances that occurred on November 4th, 2015 and show that an intense solar radio burst is the likely source of problems encountered by air traffic radar systems. We show that the sudden rise in solar radio flux density is linked to the occurrence of fine spectral radio structures hinting at a coherence emission process. From a multi wavelength analysis, we discuss which flaring conditions might trigger such strong radio emission.
|5||Active region jets on August 25, 2011||Magdalenic, J et al.||p-Poster|
| ||L. Harra, S. Matthews, D. Berghmans, V. Krupar, D. Mueller|
| ||Solar-Terrestrial Center of Excellence – SIDC, Royal Observatory of Belgium, Belgium; University College London (UCL) MSSL, UK; Institute of Atmospheric Physics ASCR, Czech Republic; European Space Agency - ESTEC, Netherlands|
| ||Solar coronal jets are impulsive, collimated features, observed at different energies. Jets are seen on the Sun at all scales - from those occurring in coronal holes to those in active regions.
This study is focused on the active region jets which occur regularly at small-scale, but can also occur on a larger scale related to CMEs and SEPs. The aim of the study is to determine why the jets occurred in this particular active region, what their dynamics are, and possibly to predict what we might see with Solar Orbiter.
Understanding the process of jets requires spectral and imaging data across different energy regimes. Therefore, we selected well observed series of jets which occurred on August 25, 2011, in the active region NOAA 1271 (located near the western solar limb).
First results of the multiwavelength study show that the repeated jets observed on August 25, originate from the western part of the active region and were associated with a small flux emergence. Due to the existence of open field lines but also a large transequatorial loop system (closed field lines), some of the type III radio bursts associated with jets propagated to the interplanetary space and some did not.
In the first radio triangulation study of radio emission associated with jets, we employed goniopolarimetric measurements taken simultaneously from STEREO A and WIND spacecraft. The reconstructed propagation paths of the interplanetary type III bursts associated with jets indicate that the fast electron beams are propagating towards the Earth, but the path does not completely coincide with the Parker spiral. This deviation in the propagation path of the electron beams associated with jets is probably due to the influence of a nearby coronal hole. |
|6||Multi-instrument observations of an X9.3 flare||Dammasch, I et al.||p-Poster|
| ||I. E. Dammasch, M. Dominique, J. Magdalenic, C. Marqué|
| ||Royal Observatory of Belgium|
| ||The radiometer LYRA on PROBA2 observed the X9.3 flare of 06 Sep 2017, the strongest flare of this solar cycle. We found flare signatures in all of LYRA's spectral channels: Lyman-alpha (120-123nm), Herzberg continuum (190-222nm), as well as EUV and SXR. These observations will be compared with GOES observations, and radio observations, by the local HUMAIN station, of the same event.
|7||Real-Time Alert System for GNSS Signal Degradation Caused by Solar Radio Bursts.||Chevalier, J et al.||p-Poster|
| ||Jean-Marie Chevalier, Nicolas Bergeot|
| ||Royal Observatory of Belgium|
| ||Intense solar radio bursts (SRBs) emitted at L-band frequencies are a source of radio frequency interference (RFI) for Global Navigation Satellite Systems (GNSS) and consequently impact the quality of the GNSS signal reception. Such space weather events are critical for GNSS-based applications requiring real-time high-precision positioning. Despite the fact that solar observatories routinely monitor solar radio emissions, the direct impact of SRB at the GNSS frequencies are not determined in real-time.
To remedy to this shortcoming, the Royal Observatory of Belgium (ROB) started to monitor in near-real time the carrier-to-noise density (C/N0) observations from regional GNSS networks. The monitoring consists in estimating abnormal fade of the C/N0 for each GNSS satellite-receiver pair with respect to the normal quiet state defined as the C/N0 median of the seven previous satellite repeat ground tracks. To distinguish the C/N0 fade due to SRBs among all other potential radio frequency interferences and ionospheric scintillations, we estimate a unique <ΔC/N0> fade over the regional network at the L1 and L2 frequencies at each epoch (30s). It allows detecting and quantifying the impact of SRBs on GNSS signal quality at a regional level.
To validate this method, the degradation of GPS and GLONASS C/N0 on the GNSS stations of the entire EUREF Permanent Network (EPN) was investigated during 11 intense SRBs close to the GNSS frequencies occurring between 1999 and 2015 in the sunlit of Europe. The analysis shows that: (1) the most intense SRB reached a <ΔC/N0> fade of 12 dB.Hz and the least intense SRB was detected with 1 dB.Hz <ΔC/N0> fade, while during quiet time the <ΔC/N0> remains stable at 0.0±0.1 dB.Hz level; (2) GPS and GLONASS ΔC/N0 fades agree at the 0.1±0.2 dB.Hz level.
Finally, a near-real time 4-level index warning system indicating the impact of a SRB on GNSS signal reception is now operational at ROB for the European region using real-time data of the EPN. It already permitted detecting the last SRB event of the 6th September 2017 with a C/N0 fade of -6.2±1.6 dB.Hz. In addition, first results for South America and Africa, obtained using GNSS data from the real-time IGS network, will also be shown.|
|8||Radio observations of recent solar flares from ESA Soil Moisture and Ocean Salinity (SMOS) Mission||Casella, D et al.||p-Poster|
| ||Raffaele Crapolicchio[1,2], Daniele Casella, Christophe Marqué|
| ||ESA-ESRIN; Serco spa; Royal Observatory of Belgium|
| ||Soil Moisture and Ocean Salinity (SMOS) is an Earth Explorer European Space Agency (ESA) mission launched in November 2009, in excellent operational status with plans to continue its operational phase beyond 2019.
The payload of SMOS consists of the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) instrument, a passive microwave 2-D interferometric full polarization radiometer, operating at 1.413 GHz (wavelength of 21 cm). The interferometry technology, initially developed for radio-astronomy, provides the opportunity to measures polarimetric microwave emissions from Earth's surface to map levels of land soil moisture and sea surface salinity with a spatial resolution of about 50km from space.
The SMOS mission is based on a sun-synchronous orbit (dusk-dawn 6am/6pm) with a mean altitude of 758 km and an inclination of 98.44°. SMOS has a 149-days repeat cycle with an 18-days sub-cycle and a revisit time of 3 days. Due to the orbit geometry and the size of the MIRAS’s antennae the Sun appears in the antenna field of view and direct Sun observation is captured by MIRAS for the full Stokes vector on the antenna plane with a temporal sampling of 3.6 seconds.
Direct observation of the Sun is actually minimized or cancelled in order to increase the accuracy of the geophysical retrievals at level 2. However, the retrieved L-band Sun brightness temperature (unit is Kelvin) available inside the SMOS Level-1b user product (L1b) is a valuable L-band radio signal that can be further used for research in the fields of solar observation and space weather.
The poster presents the preliminary results of a comparison exercise between SMOS Sun brightness temperature and measurements based on ground solar radio telescopes for a series of Sun flares events occurred in September 2017. The comparison of the two data sets has shown a strong timing correlation and an impressive correspondence in the burst amplitude. This preliminary results encourage to further extend the research activity to improve the accuracy of SMOS Sun radio observation and to further exploit the richness of SMOS dataset in term of uniformity and long-term of the measurements and the short timeliness (within 3 hours) for space weather application.