Session 6 - Radio observations for Space Weather applications

Hanna Rothkaehl (PAS), Barbara Matyjasiak (PAS), Nicole Vilmer (LESIA)
Monday 18/11, 16:00-17:15
Mozane 789

Radio observations of the Sun and the interplanetary medium provide effective diagnostics on the relevant plasma domains and perturbations that affect them.  In particular, the main originating agents of Space Weather, e.g., solar flares, eruptive prominences, CMEs, ionospheric disturbances, and Solar Wind streams emit radio waves and/or interfere with radio waves from which the resulting signals can be used as proxies in now-casting and/or forecasting activities.  Solar radio indices are used in ionospheric and atmospheric models as indicators of enhanced EUV radiation inputs as well as to identify possible RFIs to radio communication systems and GNSS receivers.  Hence, radio observations from both the ground and from space have an ever-increasing role in Space-Weather applications. 
Both dedicated and non-dedicated radio instruments have been considered in this framework, such as LOFAR and ultimately, the SKA and radio space borne satellite interferometry. 

This session is aimed at providing the state-of-the-art about the operational scenario of radio instruments for Space Weather with special attention to the required services and the forthcoming new facilities as we look to the future.

Talks
Monday November 18, 16:00 - 17:15, Mosane 789

Click here to toggle abstract display in the schedule

Talks : Time schedule

Monday November 18, 16:00 - 17:15, Mosane 789

16:00	Radio Observations for Space Weather Applications	Mann, G et al.	Invited Oral
	Gottfried Mann
	Leibniz-Institut für Astrophysik Potsdam An der Sternwarte 16 D-14482 Potsdam Germany
	The Sun is an active star. Its activity manifests not only in the well-known 11-year Sun spot cycle but also in terms of eruptive events as flares and coronal mass ejections (CMEs). During flares a large amount of stored magnetic energy is suddenly released in the corona and tranfered into local heating of the coronal plasma, mass motion as jets and CMEs, enhanced emissions of electromagnetic radiation from the radio- up to the gamma-ray range, and the production of energetic particles (e.g. electrons, protons, and heavy ions) usually called as solar energetic particle events (SEPs). All these eruptive events are accompanied with an enhanced emission of radio waves called solar radio bursts. The novel radio interferometer LOFAR (LOw Frequency ARray) with its imaging and spectroscopic capabilities is an excellent tool for observing the solar activity with radio-astronomical methods. LOFAR is working in the frequency range 10-240 MHz and, hence, as a dynamic spectroscopic imager of the Sun. Since solar eruptive events can influence the Earth’s environment and our technical civilization, it is important for the mankind to study the solar-terrestrial relationships. Results recently obtained with LOFAR show that solar radio observations especially with LOFAR are an excellent tool for space weather applications.
16:15	Comparing solar flares from SMOS and GOES missions	Cid, C et al.	Oral
	Cid Consuelo[1], Sharma Rahul[1], Flores Manuel[1], Saiz Elena[1], Guerrero Antonio[1]
	[1] Space Weather Research Group. Universidad de Alcala
	Solar flares are powerful releases of electromagnetic energy in the solar atmosphere, which are observed at all wavelengths from decametre radio waves to gamma-rays. In the standard flare model, the energy that powers the solar flares is stored in the nonpotential coronal magnetic fields. This energy is released in the corona by magnetic reconnection, in both, thermal and nonthermal domains. A part of the energy is also spent in heating the lower solar atmosphere (photosphere, chromosphere, transition-region), where the plasma is intensely heated, expand upward, and fill the nearby loop structures. The mutual relationship in between thermal and nonthermal flare emissions was first highlighted by Neupert (1968). Since, soft x-ray and radio emissions, that sample these thermal/nonthermal energy domains associated with flare spectra, are generated entirely by different physical phenomenon, these can provide key insights into the energy distribution for any flare event, important from space weather perspective. We present a systematic search of flares, using the Sun L-band brightness-temperature measurements from MIRAS instrument, onboard the SMOS mission, operating at 1.413 GHz. For the first time, the flare catalogue obtained from MIRAS/SMOS is compared with the events obtained from a systematic search in the 0.1–0.8 nm passband from SXT/GOES. The most relevant events obtained from the cross correlation between both data sets are further analyzed to better our knowledge on the physical mechanisms involved in the flares, while assessing the added value of L-Band Sun measurements for space weather applications.
16:30	The UCSD Iterative Interplanetary Scintillation (IPS) Analysis Operation Using an ENLIL 3-D MHD Model Kernel	Jackson, B et al.	Oral
	Bernard Jackson[1], Dusan Odstrcil[2], Paul Hick[1], Andrew Buffington[1], Munetoshi Tokumaru[3], Mario Bisi[4]
	[1]Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive #0424, La Jolla, CA 92093-0424, USA, [2]Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030, and NASA-Goddard Spaceflight Center, Greenbelt, MD 20771, USA, [3]Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan, [4]United Kingdom Research and Innovation – Science & Technology Facilities Council - Rutherford Appleton Laboratory, RAL Space, Harwell Campus, Oxfordshire, OX11 0QX, United Kingdom
	The University of California, San Diego (UCSD) has developed a time-dependent three-dimensional (3-D) reconstruction technique that provides volumetric maps of density and velocity by iteratively fitting 3-D MHD models to interplanetary scintillation (IPS) observations. This system is compared with NOAA and NASA-provided in-situ measurements and is now being evaluated for use in real time predictions of solar wind parameters on the UCSD website https://ips.ucsd.edu/ENLIL_prediction, in order to validate its operation in different types of conditions. Unlike previous UCSD kinematic modeling, our new tomographic analysis with a 3-D MHD kernel now includes shock processes and the non-radial transport of structure from the inner-boundary source surface at 0.1 AU. Magnetic fields are extrapolated outward from the solar surface to support the iterative procedure, and are shown to provide a low resolution several-day advance prediction of GSM Bz and geomagnetic storms. Used currently with data available from ISEE, Japan, this type programming will be especially important when more data become available from Worldwide IPS Stations (WIPSS) network groups and both spatial and temporal IPS coverage is increased. Our modeling system complements existing operating systems at different world Space Weather Prediction Centers that currently use modeling based primarily on magnetogram observations and US and European spacecraft, and will ensure solar wind prediction robustness in case of different instrumentation failures.
16:45	Assessment of Space Weather effects on navigation applications using radio observations	Berdermann, J et al.	Oral
	Jens Berdermann, Mainul Mohammed Hoque, Martin Kriegel, Daniela Banys, Volker Wilken, Norbert Jakowski
	German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, Germany
	During the past decades a growing number of radio observations are available with the potential to significantly improve monitoring and modelling of the ionosphere. This is important since radio signals transmitted by modern communication, navigation and Earth observation systems are also influenced during propagation through or by reflection at the ionosphere, depending on the used frequency. The combination of ground- and space-based data together with appropriate modelling can provide unique information about the ionosphere. We will present how well established and new ionospheric measuring and observation methods can help to improve our understanding of the ionosphere and its dynamics. Finally, we show the impact of selected Space Weather events on navigation systems and services based on data from radio observations.
17:00	Towards developing a nowcasting solar flare capability using subionospheric VLF radio: Addressing the ICAO call for global aviation	Rodger, C et al.	Oral
	Craig J. Rodger[1], Harriet George[1,2], Mark A. Clilverd[3], Kathy Cresswell-Moorcock[1], James B. Brundell[1], Neil R. Thomson[1]
	[1] Department of Physics, University of Otago, Dunedin, New Zealand, [2] University of Helsinki, Helsinki, Finland, [3] British Antarctic Survey (NERC), Cambridge, United Kingdom
	Solar flares are often the first indicator of a sequence of space weather events that have the potential to impact societal technology. They are linked to processes which disrupt maritime mobile services, emergency responders, land-based high-frequency (HF) communications, and the aviation industry. Amendment 78 to the International Civil Aviation Organization (ICAO) Annex 3 (application date November 2018) identifies solar flares and solar storms as potential hazards that affect communications, navigation, and could pose a radiation risk to aircraft crew and passengers. Because of this ICAO has released a draft Manual of Space Weather Information in Support of Air Navigation. This manual indicates that early warning of solar flare driven HF radio blackout occurrence, duration and severity is a requirement for ICAO. Solar flares of X1 class are identified by ICAO as requiring a moderate space weather advisory of likely weak HF radio communication, while an X10 flare requires a severe advisory due to likely HF radio blackout conditions. Forecasting of solar flare occurrence is an outstanding problem. Predictive techniques using morphological methods based on observed parameters have been developed but currently have low forecast skill scores, particularly for large, infrequent flares. In light of the difficulties in forecasting large solar flares it is imperative that a swift nowcast capability is developed, with the ability to rapidly detect and classify enhanced solar x-ray flux levels. Nowcasting of solar flares needs to identify when a flare has occurred, when it has reached a disruptive size, when it has peaked, how large the fluxes are at the peak, and how long the flare effects will last. In this study we present a technique for analysing very low frequency (VLF) radiowave signals in order to achieve rapid, real-time detection of solar flares for nowcasting by space weather forecast centres, through changes in VLF radio signal propagation conditions. We investigate the reliability of VLF phase and amplitude perturbations, during large solar flares, to determine the x-ray fluxes involved. We identify the most accurate parameterisation needed to develop nowcasting equations relating VLF phase perturbations with longwave x-ray fluxes (0.1-0.8 nm, XL), and show that other relationships involving VLF amplitude perturbations, and shortwave x-ray fluxes (0.05-0.4 nm, XS), are less reliable.

Posters

1	Statistical analysis of medium scale GWs (TIDs) during solar cycle	Rusz, J et al.	p-Poster
	Jan Rusz[1], Jaroslav Chum[1]
	[1] Institute of Atmospheric Physics CAS, Bocni II/1401, 14100 Prague 4, Czech Republic
	The statistical analysis is based on measurements by multi-point continuous Doppler sounding (CDS). The measuring network consists of Doppler sounders in the western half of the Czech Republic. The network consists of at least three spatially separated sounding paths (transmitter-receiver pairs) at each frequency; three different frequencies are used since the last solar maximum in 2014. The apparent horizontal velocity and azimuth of gravity waves were calculated from the time delays observed between Doppler shift time series derived from signals recorded for different measuring paths. The observed parameters are statistically processed and the results from the solar maximum and minimum periods are compared.
2	A new approach to radio observations for forecasting shock arrival	Jebaraj, I et al.	p-Poster
	I. Jebaraj[1,2], J. Magdalenic[1], C. Scolini[1,2], T. Podlachikova[3,4], K. Dissauer[4], J. Pomoell[5], L.Rodriguez[1], E. Kilpua[5], V. Krupar[6][7][8], A. Veronig[4], S. Poedts[2]
	[1]SIDC, Royal Observatory of Belgium, 1180 Brussels, Belgium, [2]CmPA, Department of Mathematics, KU Leuven, 3001 Leuven, Belgium, [3]Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Building 3, Moscow 143026, Russia [ 4]Institute of Physics/IGAM, University of Graz, Graz, Austria [5]University of Helsinki, Helsinki, Finland [6]NASA Goddard Space Flight Center, Greenbelt, MD, USA [7]Universities Space Research Association, Columbia, USA 8Institute of Atmospheric Physics CAS, Prague, Czech Republic
	The disturbed geomagnetic conditions at the Earth, i.e. geomagnetic storms, are mainly driven by the Coronal mass ejections (CMEs) and associated shock waves. Therefore, tracking of CMEs and shocks and predicting their arrival at the Earth is an important scientific topic in the space weather. The shock associated radio emission, so called type II radio bursts, is frequently used to forecast the shock arrival to the Earth. The success of such a forecast is very variable. Forecasting results strongly depend on the source position of the radio emission relative to the CME (CME-flank or CME leading edge). Combination of the ground based and space-based radio observations provide us the unique opportunity to track shock waves starting from the Sun and to the inner heliosphere, and relate these observations with the CME observed in the white light. Herein we present rather novel technique so called radio triangulation, which surpasses the classically used 2D analysis of radio emissions and application of the 1D density models. Using stereoscopic radio observations, so called goniopolarimetric observations from the WAVES instrument onboard WIND, STEREO A and STEREO B, we can identify the source positions of interplanetary radio emission in the 3D space. The obtained results are then compared with the associated CME with the aim to understand if the CME-flank or the CME leading edge is the preferable type II source position. We study the CME/flare event on September 27/28, 2012. The GOES C3.7 flare was associated with the full-halo CME (first seen in the SOHO/LASCO C2 field of view at 23:47 UT) and white light shock observed by all three spacecraft STEREO A, STEREO B, and SOHO. The associated radio event is composed of a groups of type III bursts and two type II bursts with different starting time and frequency. The radio triangulation study shows that the first type II burst seem to be CME-driven, but the second type II occurs significantly higher in the solar corona than the CME, and has unclear origin. Since the radio source positions of the second type II are situated close to the nearby streamer, we believe that the shock wave – streamer interaction is the source of the second type II burst. In this event, using the second type II burst to predict the shock wave arrival at the Earth will be highly unreliable, showing large difference between the observed and predicted shock arrival.
3	Investigation of ionospheric disturbances by continuous HF Doppler sounding	Chum, J et al.	p-Poster
	Jaroslav Chum[1], Jan Lastovicka[1], Jan Rusz[1]
	Institute of Atmospheric Physics CAS, Bocni II/1401, 14100 Prague 4, Czech Republic
	Continuous Doppler sounding (CDS) is a useful tool to investigate short-time fluctuations of plasma at specific heights in the ionosphere; its time resolution is about 10 s, which is much higher than the time resolution of ionospheric sounders that measure ionospheric profile. On the other hand, CDS cannot determine the height of observation. It is therefore useful to combine measurements by CDS and by a nearby ionospheric sounder that can be used to estimate the reflection height of the CDS. Examples of analysis and detection of various ionospheric disturbances such as medium scale travelling ionospheric disturbances caused by gravity waves or infrasound, sudden ionospheric disturbances caused by solar flares or movement of ionospheric plasma induced by electric fields associated with sudden storm commencements and geomagnetic activity will be presented.
4	In situ and remote radio diagnostic of large high latitude ionospheric structures	Rothkaehl, H et al.	p-Poster
	D. Przepórka, B. Matyjasiak, H. Rothkaehl, M. Pożoga, Ł. Tomasik
	CBK PAN , Warsaw, Poland.
	One of the pronounced and highly sensitive to changes in geomagnetic conditions regions of ionosphere is the mid-latitude trough. It is an unique area of the Earth's environment, where different type instabilities and impact from bottom part of the atmosphere and remote region of magnetosphere can meet.The mid-latitude trough manifests itself as a significant depletion in the electron density and electron temperature increase in the sub-auroral region of the topside ionosphere. Especially distinct feature is that the trough properties change accordingly to the geomagnetic storm phase. In particular it moves equatorward with the storm onset, and as the storm develops it narrows and deepens. The aim of this presentation is to show the qualitative and quantitative answer for the question how the geomagnetic activity impacts the mid-latitude trough characteristics. The special emphasis was placed on the description of different reaction of north and south mid-latitude trough for different solar and geomagnetic conditions. The studies are based on the data set gathered by the different radio diagnostics onboard DEMETER, SWARM, COSMIC mission and GNSS diagnostics. .
5	Simultaneous TEC and HF ionospheric scintillation observations from GPS and LOFAR station.	Pozoga, M et al.	p-Poster
	Barbara Matyjasiak, Marcin Grzesiak, Lukasz Tomasik
	Space Research Centre Polish Academy of Sciences
	The mid latitude ionospheric scintillation observed on LBA band (10-90MHz) by PL610 LOFAR station are quite common phenomenon. Due to the dependency of scintillation strength on observed frequency and different size of irregularities contributing to scintillation effect it is difficult to observe it at GNSS frequencies. However, the number of available receivers allows to obtain TEC measurements with 1 second accuracy near predicted pierce point of LOFAR observation. In this work we show the TEC measurements that are co-located with the observations made by LOFAR PL610 station in local mode. We also compare ROTI and scintillation spectra recorded with both instruments. We aim at showing that the combination of measurements can allow a better understanding of the processes responsible for the formation of ionospheric scintillations in mid latitude region.
6	Radio Observations of the Sun and the Solar Corona with LOFAR	Zucca, P et al.	p-Poster
	Pietro Zucca [1] and the LOFAR solar and space weather KSP
	[1] ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo, The Netherlands
	LOFAR imaging capabilities allow for the detailed study of eruptions and transients in the solar corona. A series of recent examples will be shown including Type III, II and IV radio bursts. In particular, a new study on a series of three consecutive type II radio bursts observed with the interferometric mode of LOFAR will be presented. Using core and remote stations a spatial resolution of 15 arcseconds may be achieved. The detailed propagation of the radio bursts and the study of the related fine structures such as the band splitting phenomena will be presented. The presentation includes a discussion of the new observing modes and capabilities of LOFAR for solar observations and a detailed comparison of LOFAR imaging with previous facilities such as the Nancay Radio heliograph.
7	The formation and evolution of a shock driven by a coronal mass ejection in the low corona	Maguire, C et al.	p-Poster
	Ciara A. Maguire[1,2], Eoin P. Carley[1,2], Pietro Zucca and Peter T. Gallagher[2,1]
	[1]School of Physics, Trinity College Dublin, Dublin 2, Ireland [2]School of Cosmic Physics, Dublin Institute for Advanced Studies, Dublin D02 XF85, Ireland [3]ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990, AA Dwingeloo, The Netherlands
	The Sun can produce large-scale energetic events such as coronal mass ejections (CMEs) which can excite shock waves that propagate through the corona. A super-Alfvénic shock can result in particle acceleration and subsequent radio emission, known as a type II burst. To date, the methods used to determine the Alfvénic Mach number of a CME-driven shock have been used independently and the results from each method have not been compared. Here, we compare Alfvénic Mach numbers $M_A$ derived from three different commonly used methods namely: shock geometry, a comparison of CME speed to a model of the coronal Alfvén speed, and the type II substructure method. Here we applied the three methods to the 2017 September 2 event, focusing on the evolution of the CME and shock wave observed in extreme ultra-violet (EUV) by the Solar Ultraviolet Imager (SUVI) telescope on board GOES-16, in white-light by the Large Angle and Spectrometric Coronagraph (LASCO) C2 on board Solar and Heliospheric Observatory (SOHO) and the type II radio burst observed by the Irish Low Frequency Array (I-LOFAR). Within error the Alfvénic Mach numbers derived from the three methods are consistent. The type II radio emission was found to be located at the expanding nose region of the CME, when it reaches a height of $\sim$1.6 R$_\odot$ and $M_A$ of $\sim$1.6. We find that the type II radio emission ceases when the shock front reaches $\sim$2.4 R$_\odot$ despite an increasing $M_A$ (up to 4). We suggest this is a result of a change in shock conditions at $\sim$2 R$_{\odot}$ after which the shock geometry changes, inhibiting electron acceleration and radio emission. These results shows that conditions for producing type II emission are more than just a super-Alfvénic eruption and favourable shock geometry for the acceleration of energetic electrons is required.
8	Lofar4SpaceWeather: Towards Space Weather Monitoring with Europe’s Largest Radio Telescope: Status at Mid Term Review.	Mevius, M et al.	p-Poster
	Maaijke Mevius[1], Eoin Carley[3], Richard Fallows[1], Agnes Mika[1], Nicole Vilmer[2], Peter Gallagher[3], Mario Bisi[4], Joris Verbiest[5], Hanna Rothkaehl[6], Michael Olberg[7], Rene Vermeulen[1]
	[1] Astron, the Netherlands [2] Observatoire de Paris, France [3] Trinity College Dublin (TCD), Ireland [4] RAL Space, UK [5] Bielefeld University, Germany [6] CBK Warsaw, Poland [7] Onsala Space Observatory (OSO), Sweden
	LOFAR is the world's largest low frequency radio telescope, with a dense core in the Eastern part of the Netherlands and many stations distributed both in the Netherlands (with baselines reaching 100s of kms) and Europe wide (with baselines up to 2000 km). The existing infrastructure not only offers a great tool for a variety of radio astronomical observations, but the sensitivity and flexibility of the system also allows for dedicated space weather studies. Lofar4SW is a design study, awarded a grant under the Horizon2020 INFRADEV call, to commence investigations into upgrading LOFAR to enable regular space weather monitoring observations in parallel with radio astronomy operations. The project will have its mid term review in September. In this presentation we will summarize the aims and discus the current status of the Lofar4SW design study and provide an outlook to the space weather science and monitoring capabilites a fully integrated system would enable.
9	Studying the Ionosphere with LOFAR	Mevius, M et al.	p-Poster
	Maaijke Mevius[1], Richard Fallows[1], Andzrej Krankowski[2] Kacper Kotulak[2] Marcin Grzesiak[3], Mariusz Pozoga[3], Barbara Matyjasiak[3], Hanna Rothkaehl[3]
	[1] Astron, the Netherlands [2] UWM Olsztyn, Poland [3] CBK Warsaw, Poland
	The LOw Frequency ARray (LOFAR) is world's largest radio telescope operating at frequencies between 10 and 240 MHz. At these frequencies the ionosphere poses a one of the main challenges in the calibration of the radio astronomical data, since many of the ionospheric effects on electromagnetic radiation scale with wavelength of the signal. What is a challenge for the radio astronomer is a benefit for the ionospheric physicist: the level of details in the information on ionospheric structures that can be extracted from the calibration parameters and dedicated observations is astonishing. The possibilities of ionospheric measurements with Lofar will be illustrated in this presentation. We will elaborate on a few ionospheric studies that were done using Lofar data. These include Traveling Ionospheric Disturbance (TID) detection, a novel method for absolute TEC measurements and studies of scintillation data. We will present a case from August 2013 which shows quite strong scintillation in Cas A above the Dutch array, with the Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) showing two arc structures which may indicate scintillation from two different ionospheric layers. Current indications are that this was likely due to a TID, possibly triggered by minor geomagnetic storm conditions over the Arctic. This scintillation event will be combined with a full GNSS elaboration.
10	Introduction to IRNSS and initial Results of Total Electron Content at Sangli	Shetti, D et al.	p-Poster
	D.J.Shetti[1], M. S. Manjarekar[1], T.S.Vasagade[2]
	[1] Smt Kasturbai Walchand College, Sangli - 416415, [2] Annasaheb Dange College of Engineering and Technology, Ashta – 416301
	IRNSS (Indian Regional Navigation Satellite System) is India’s independent regional navigational satellite system. This system works with two frequencies L5 (1176.45 MHz) and S band (2492.08 MHz). Paper comprises the basic details of IRNSS system first and further extends to present first result of TEC (Total Electron Content) estimation. The estimation of TEC is the major parameter to analyze performance of navigation system. Hence, these results will surely play important role to have an idea of present working scenario of IRNSS with respect to efficiency and effect of space weather on it. All these estimation is carried out using Low Latitude Station, Sangli (16° 52' 0" North, 74° 34' 0" East). IRNSS-UR is the software, used for receiving and extracting data. Codes are developed in MATLAB programming tool for estimating TEC using RINEX 3.03 Data Format. Keywords: IRNSS system, TEC estimation, Estimation of Group delay and Phase Delay for IRNSS
11	Radio bursts of active region AR12740 under solar minimum conditions	Octavian, B et al.	p-Poster
	Octavian Blagoi, Cristian Danescu
	Astronomical Institute of Romanian Academy
	Study of solar radio bursts recorded by e-CALLISTO network of active regions AR12740 under solar minimum conditions. Correlation between x-ray flux, CME and radio burst emissions.