Session 12 - Thermosphere and Ionosphere : Irregular dynamics and structures as a response to Space Weather Events
Mirko Piersanti (University of L'Aquila), Massimo Materassi (CNR, Italy)
Friday 9/11, 09:00-10:30 & 11:15-12:45
MTC 00.15, Small lecture room
The Thermosphere – Ionosphere system is a medium highly structured on many time and spatial scales. On the one hand, it shows rather stable and robust large patterns of convection and currents (such as Sudden Impulses current convection pattern); on the other hand, high and low latitudes show very irregular, highly time-variable small scale patterns (namely, plasma turbulence causing scintillation on trans-ionospheric L-band signals, plasma bubbles, large scale travelling ionospheric disturbance). Both the exact mechanism of response to external drivers, and the role played by the thermosphere (in terms of neutral wind, atmospheric waves and plasma drift) in generating Ionosphere irregularities is not completely understood yet.
In the last two decades, the interest in Ionospheric irregularities at different time and space scales has been growing fast, because of the considerable effects on the manmade technological infrastructure such as: geomagnetically induced currents, or the threats to performance of the satellite communication and navigation. Since those irregularities are due to the presence and variability of plasma structures in the ionosphere, understanding physical mechanisms that regulate the formation of the latter and their dynamics, as a result of magnetosphere-ionosphere-thermosphere coupling, is crucial to develop reliable prediction models and mitigation techniques, in order to be able to tackle the effect on technological systems.
This Session solicits and welcomes contributors to make the point on their research about how such multiscale patterns respond to the Sun activity and to the ionosphere-thermosphere interaction. Such a subject is very relevant from a technological point of view as both radio communications and industrial facilities may be vulnerable to plasma turbulence and ionospheric induced currents at ground, respectively.
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Talks : Time scheduleFriday November 9, 09:00 - 10:30, MTC 00.15, Small lecture room| 09:00 | On the Role of Dynamical Complexity and Turbulence in the Ionosphere | Consolini, G et al. | Invited Oral | | | Giuseppe Consolini | | | INAF-Istituto di Astrofisica e Planetologia Spaziali, 00133 Roma, Italy | | | In the last twenty years it has been realized that several processes and phenomena occurring in circumterrestrial plasmas are characterized by dynamical features that cannot be simply understood in terms of classical fluid and MHD approaches. In particular, it has been shown that dynamical complexity and turbulence are phenomena that play a fundamental role in generating the multiscale features of these plasma media. Here, the meaning and the role that dynamical complexity and turbulence might take part in generating multiscale structures in the Earth’s ionosphere, are discussed in relationship with their relevance to Space Weather studies. Some recent results on the ionospheric plasma turbulence by ESA-Swarm mission will also be presented and discussed. | | 09:30 | Investigating dynamical complexity in the topside ionosphere using information-theoretic measures | Balasis, G et al. | Oral | | | Georgios Balasis[1], Adamantia Zoe Boutsi[1], Constantinos Papadimitriou[1] | | | [1]National Observatory of Athens | | | Recently, many novel concepts originated in dynamical systems or information theory have been developed, partly motivated by specific research questions linked to geosciences, and found a variety of different applications. This continuously extending toolbox of nonlinear time series analysis highlights the importance of the dynamical complexity to understand the behavior of the complex Earth's system and its components. Here, we propose to apply such new approaches, mainly a series of entropy methods to the time series of the Earth's magnetic field measured by the Swarm constellation. Swarm is an ESA mission launched on November 22, 2013, comprising three satellites at low Earth polar orbits. The mission delivers data that provide new insight into the Earth's system by improving our understanding of the Earth's interior as well as the near-Earth electromagnetic environment. We show successful applications of methods originated in information theory to quantitatively studying complexity in the dynamical response of the topside ionosphere, at Swarm altitudes, to space weather events. | | 09:45 | New capabilities for prediction of high-latitude ionospheric scintillation: A novel approach with machine learning | Mcgranaghan, R et al. | Oral | | | Ryan McGranaghan[1,2], Anthony Mannucci[1], Brian Wilson[1], Chris Mattmann[1] | | | [1]NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, [2]University Corporation for Atmospheric Research, Boulder, CO, USA | | | Space weather has a wide-reaching impact on technological systems. Among the critical affected technologies are those dependent on radio signals propagating through the complex, variable ionosphere, especially those from Global Navigation Satellite Systems (GNSS). Complexity and multi-scale variability (in both time and space) characterize the ionosphere and threaten the integrity of GNSS signals. However, these signals also provide better spatial coverage at a higher cadence than any single ionospheric data set. We present a new data-driven approach to the prediction of ionospheric disturbances to GNSS signals, specifically scintillation, by taking advantage of years of GNSS scintillation data. These data are used to train a supervised machine learning classification model known as a support vector machine (SVM) [1]. We focus for the first time on high-latitudes, where space weather effects are most direct and no prediction capability currently exists. We show through robust quantitative metrics (i.e., beyond the conventional visual assessment) that this method produces a high degree of accuracy in predicting high-latitude scintillation with one-hour lead times based on the current state of the ionosphere, geomagnetic environment, and solar wind.
We discuss the use of this new predictive capability as a predictive benchmark and the manner in which this work embodies the future of space weather by placing focus on prediction, taking a data-driven approach, and leveraging state-of-the-art techniques that can evolve traditional approaches in lieu of the growing and complex space weather observational system.
| | 10:00 | Solar Activity and Space Weather Effects on Earth's Thermosphere | Berrilli, F et al. | Oral | | | Francesco Berrilli, Carlo Cauli, Mija Lovric, Alberto Bigazzi, Dario Del Moro, Luca Giovannelli, Marco Colace | | | Department of Physics, University of Rome Tor Vergata, Italy | | | The radiative output of the Sun is variable on different time scales, but the most prominent variability over the last few centuries has been the 11-year cycle. Total Solar Irradiance shows changes of around 0.1% during the 11-year cycle, with different spectral regions (e.g. UV) changing by different amounts. Solar UV variability is essential to understand Space Weather and related long-term changes in the Earth's upper atmosphere.
SOLSTICE/SORCE data are used to investigate the variability in Far Ultraviolet (FUV) and Middle Ultraviolet (MUV) during the descending phase of cycle 23 and ascending phase of cycle 24. The [FUV-MUV] color index is introduced to describe the solar UV spectral slope and describe its dependence on solar activity. The solar UV spectral slope between 1978 and today is reconstructed using the Mg II core-to-wing ratio index.
Solar activity indices, such as the Mg II, the F10.7 flux and the Ap geomagnetic index, have been used to investigate the impact of solar activity on thermosphere density during ESA's gravity mission GOCE (17 March, 2009 - 11 November, 2013, rising phase of solar cycle 24). Thermosphere densities at a mean altitude of 254 km, derived from the high-precision accelerometers on board the GOCE satellite, represent a unique low-altitude dataset. Solar activity indices in the period of GOCE mission have been firstly examined in time and their correlations with GOCE thermosphere density have been studied. Then, solar indices have been analysed through the Empirical Mode Decomposition (EMD). After extracting the individual components (IMFs) from the solar indices, thermosphere density have been reconstructed and compared with the GOCE dataset. The preliminary results presented in this work suggest how significant advantages may be gained using the Mg II index and EMD method in describing the solar-thermosphere connection.
| | 10:15 | A self-consistent approach to analysis of ionospheric and thermospheric parameter long-term trends | Mikhailov, A et al. | Oral | | | A.V. Mikhailov[1] and L. Perrone[2] | | | [1]Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN); [2]Istituto Nazionale di Geofisica e Vulcanologia (INGV) | | | A recently proposed method to extract thermospheric parameters (neutral composition O, O2, N2, temperature Tex, meridional wind) as well as the total solar EUV flux with < 1050Å from routine ionosonde foF1 and foF2 observations opens an opportunity to analyze in a self-consistent way long-term variations of both ionospheric and thermospheric parameters. Using European June daytime ionosonde observations long-term variations of above mentioned parameters have been analyzed for the (1958-2017) period. Significant negative foF1 and foF2 trends are due to corresponding changes in neutral composition and temperature. The height of F2-layer maximum, hmF2 found in a self-consistent way with other aeronomic parameters manifests also a negative trend resulted from the increase of the Northward thermospheric wind. The latter is due to a decrease in ion drag (due to negative trends in foF2) and to a decrease in auroral heating related to a decrease in solar and geomagneric activity over the analyzed period.
All long-term variations of thermospheric parameters (neutral temperature and composition) have a natural (not anthropogenic) origin reflecting long-term variations in solar and geomagnetic activity.
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Friday November 9, 11:15 - 12:45, MTC 00.15, Small lecture room| 11:15 | An assessment of the ability of the TIEGCM Rayleigh-Taylor growth rate to reproduce the daily occurrence variability of Equatorial Plasma Bubbles | Carter, B et al. | Invited Oral | | | Brett A. Carter[1], J. Currie[1], M. Terkildsen[3], K. Groves[3], R. Caton[4] | | | [1] RMIT University, Melbourne, Australia, [2] BoM, [3] Boston College, [4] AFRL | | | Equatorial Plasma Bubbles (EPBs) are nighttime ionospheric disturbances in which low-density plasma becomes immersed within high-density plasma at higher altitudes above the equator; a process caused by the Generalized Rayleigh-Taylor (R-T) plasma instability. The generation of EPBs gives rise to an entire spectrum of plasma waves/structures that can influence radio signals that propagate through them across various wavelengths. One notable impact is the ability of EPBs to adversely impact applications that use UHF/VHF satellite communications and L-band Global Navigation Satellite Systems, such as the Global Positioning System (GPS). These impacts on technologies have motivated the research field to work on the development of reliable EPB occurrence forecasts. While the seasonal/longitudinal variability of EPBs is rather well understood and reproducible from year to year – aside from the well-documented solar activity dependence – the daily occurrence variability has remained a scientific challenge for several decades. Recent studies have shown that the R-T linear growth rate calculated from the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) outputs is capable of reproducing the observed daily variability of EPBs during the peak EPB season. In these works, it was shown that regular EPB suppressions during peak EPB season are caused by decreases in the pre-reversal enhancement in the upward plasma drift, which were caused by changes in the zonal neutral wind following small-to-moderate increases in geomagnetic activity some hours earlier; i.e., well-known as the disturbance dynamo. While not all EPB suppression days were successfully captured by the TIEGCM, the success probability reached more than 90% for some station locations. In this study, peak EPB seasons over a 1-year period are analysed using scintillation data from a collection of collocated GPS and UHF receiver locations around the world, and compared to the R-T growth rate calculated from the TIEGCM. The ability of the model to capture the observed daily variability of scintillation is assessed and the appropriate metrics to measure success are discussed. It is reported that the TIEGCM exhibits a good level of success in capturing EPB variability, in line with the results of previous works. Although, it is clear from the results of this study that ongoing efforts to couple thermosphere-ionosphere models to the lower atmosphere, and the incorporation of physically accurate penetration electric fields within those models, are needed in order to successfully capture the remaining EPB daily variability.
| | 11:45 | TechTIDE Horizon 2020 project: Warning and mitigation technologies for travelling ionospheric disturbances effects | Belehaki, A et al. | Oral | | | Anna Belehaki[1] and the TechTIDE consortium[2] | | | [1]National Observatory of Athens, Greece; [2] http://techtide.space.noa.gr/?page_id=1073 | | | Travelling Ionospheric Disturbances (TIDs) is an important space weather effect in the upper atmosphere, driven by the near-Earth space dynamics and by lower atmosphere phenomena. Independent of their source, TIDs can impose significant disturbances in the electron density, and Doppler frequency shifts on High Frequency (HF) signals, affecting all technologies using predictable ionospheric characteristics. Recently it is clearly demonstrated that TIDs can have multiple effects in the operation of aerospatial and ground-based infrastructures and especially in the European Geostationary Navigation Overlay Service (EGNOS) and Network Real-Time Kinematic (N-RTK) services, in HF communications, in radio reconnaissance operations and in Very High Frequency – Ultra High Frequency (VHF – UHF) radiowave propagation. The EC Horizon 2020 Project TechTIDE has the objective to design and test new viable TID impact mitigation strategies for the technologies affected. For this purpose, it is primarily required to develop a system able to calculate in real-time the main TID characteristics (velocity, amplitude, propagation direction) and to realistically specify background ionospheric conditions. The talk reviews on several methodologies for the identification and tracking of TIDs and reports on results obtained from HF experiments and from GNSS TEC analysis techniques comparing to 3D reconstruction models. | | 12:00 | TIDs triggered by CIR/HSSS-related storms | Buresova, D et al. | Oral | | | Dalia Buresova[1], Jaroslav Chum[1], Anna Belehaki[2], David Altadill[3], Estefania Blanch[3], Daniel Kouba[1], Ivan Galkin[4], Zbynek Mosna[1], and Jaroslav Urbar[1] | | | [1]Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic;[2]National Observatory of Athens, IAASARS, Penteli, Greece;[3]University of Ramon Llull, Observatory Ebre, CSIC, Roquetes, Spain;[4] University of Massachusetts Lowell, Space Science Laboratory, Lowell, MA USA | | | The paper presents results of the analysis of changes in the regular ionospheric variability and GW activity observed over European middle latitudes during CIR/HSSS-related storms (12 events in total) which occurred within the period of 2016-2017. We analyzed variation of the main ionospheric parameters retrieved from the manually scaled ionograms, Pruhonice Digisonde DPS-4D drift measurements and spectrograms obtained from the Czech Continuous Doppler Sounding System (CDSS). There are also presented results of wave activity analysis carried out in the frame of H2020-COMPET-2017 TechTIDE project (Warning and Mitigation Technologies for Travelling Ionospheric Disturbances Effects) using selected methodologies and special tools. The results were compared with those obtained for strong magnetic storms of CME origin. During the analyzed CIR/HSSS-related events we observed significant TID activity lasting for several days. Most of the observed storm-related TIDs had periods in the range of 60-180 min. During the analyzed events we also observed extraordinary spreads and plasma bubbles at the F region heights. | | 12:15 | Towards the calibration of empirical and physics-based thermospheric neutral density models considering ionosphere coupling | Lalgudi gopalakrishnan, G et al. | Oral | | | Ganesh Lalgudi Gopalakrishnan, Michael Schmidt, Sergei Rudenko and Mathis Blossfeld | | | Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM) | | | In this presentation we analyze the coupled thermosphere-ionosphere processes by using empirical and physical thermosphere models. We start with expressing the thermospheric neutral density of a physics-based model as a function of the thermospheric density predicted from an empirical climatology model (based on a consistent set of initial conditions). This allows the direct calculation of a bias (in particular scale and offset) between the two models. The investigated problem may be extended to a vertical neutral-to-neutral coupling study between a fixed number of altitudes from adjacent layers of the thermosphere. This allows an extended analysis of the above mentioned bias parameters and their dependency on the coupling from above or below.
Furthermore, the effect of the electron and the ion density in determining the magnitude of the neutral density is investigated. Therefore, a linear model is set up to express the thermospheric neutral density as a function of two sets of ionosphere parameters, namely the electron density and the ion density. From these investigations specific insights are expected on the interactions between charged and neutral particles. It is known that the relationship between the thermospheric neutral density and the ionospheric electron density is latitude-dependent. Several dynamical and physical phenomena such as the auroral precipitation and the equatorial electro-jet are embedded in this relationship.
The altitude range used in our analysis lies between 100 and 500 km above the Earth’s surface. Two thermosphere models are used, namely the empirical NRLMSISE-00 model and the physics-based one TIE-GCM. Both are complementing each other very well in terms of complexity, spatio-temporal resolution, the general circulation and the long term climatology. The physical significance of monitoring the thermosphere-ionosphere coupling is transformed to the problem of modeling the state of the thermosphere at a given time by using ionosphere parameters such as the electron and the ion density at the same time. Subsequently, we show that the modeling problem can be posed as a parameter estimation problem. Additional model investigations, e.g., on measurement noise and non-linearity are discussed in our presentation. Finally, using satellite laser ranging measurements to a few low Earth orbiting satellites we estimate scale factors of thermospheric neutral density provided by two models under investigation. | | 12:30 | The detection of ultra-relativistic electrons in low Earth orbit by the LYRA instrument on board the PROBA2 satellite | Katsiyannis, T et al. | Oral | | | Athanassios C. Katsiyannis[1], Marie Dominique[1], Viviane Pierrard[2,3], Graciela Lopez Rosson[2,3] | | | [1] Royal Observatory of Belgium, [2] Royal Belgian Institute for Space Aeronomy, [3] University Catholique de Louvain | | | We present the analysis of energetic electrons, indirectly detected at an altitude of ~700 km by the Large Yield RAdiometer (LYRA) instrument on board ESA's Project for On-board Autonomy 2 (PROBA2) satellite in the form of microbursts of <10 ms, with a phenomenon duration of 100 s. Combining Energetic Particle Telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. Additionally, they are well confined geographically within the L=4-6 McIlwain zones, and they show a prominent dawn-dusk asymmetry. A combination of various magnetospheric mechanisms is proposed as a starting point towards a full quantitative explanation.
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Posters| 1 | The response of the ionosphere to HILDCAA events over the African mid-latitude sector | Matamba, T et al. | p-Poster | | | Tshimangadzo Merline Matamba[1,2], John Bosco Habarulema[1,2] | | | [1]South African National Space Agency Space Science, Hermanus, 7200,South Africa, [2] Department of Physics and Electronics, Rhodes University, Grahamstown, South Africa | | | The response of the ionosphere to High-intensity, long-duration, continuous AE activity (HILDCAA) events that occurred during the solar cycle 23 and 24 will be presented. HILDCAA are magnetospheric/ionospheric events that occur during high-speed solar wind streams. During solar minimum, the corotating interaction regions (CIRs) are followed by lengthy (days to weeks) periods of HILDCAA intervals characterised by low Disturbance storm time (Dst) index. The HILDCAA events were selected based on the high intensity, long duration, continuous Auroral electrojet (AE) activity where AE peak values exceed 1000 nT, the duration were greater than 2 days and the AE values never drop to 200 nT for more than two hours at a time. The HILDCAA must occur outside the main phases of the geomagnetic storms. The critical frequency of F2 layer (foF2) and Global Navigation Satellite System (GNSS) Total electron Content (TEC) over the African mid-latitude region will be used to analyse the ionospheric responses. Some physical processes responsible for the ionospheric responses will be discussed. | | 2 | Atmospheric density determination using high-accuracy satellite GPS data | Ren, T et al. | p-Poster | | | TingLing Ren[1], Juan Miao[2], SiQing Liu[3] | | | [1]National Space Science Center, Chinese Academy of Sciences, [2]College of Earth Sciences, University of Chinese Academy of Sciences | | | Atmospheric drag is the main source of error in the determination and prediction of the orbit of low Earth orbit (LEO) satellites; however, empirical models that are used to account for this often have density errors of around 15%–30%. Atmospheric density determination has thus become an important topic for researchers. Based on the relationship between the atmospheric drag force and the decay of the semi-major axis of the orbit, we derived atmospheric density along the trajectory of challenging mini-satellite payload (CHAMP) satellite with its rapid science orbit (RSO) data. Three primary parameters—the ratio of cross-sectional area to mass, the drag coefficient, and the decay of the semi-major axis caused by atmospheric drag—were calculated. We also analyse the source of the error and made a comparison between the GPS-derived and reference density. The result for December 2, 2008, showed that the mean error of the GPS-derived density could be decreased from 29.21% to 9.20%, if the time span adopted for the process of computation was increased from 10 min to 50 min. The result for the entire month of December indicated that a density precision of 10% could be achieved, when the time span meets the condition that the amplitude of the decay of the semi-major axis is much greater than its standard deviation. | | 3 | Electron Density anomalies recorded by ground and satellite instruments in correspondence of Rome during the last solar minimum | Perrone, L et al. | p-Poster | | | A. De Santis, A. Ippolito, D. Marchetti, C. Cesaroni, L. Spogli, L. Perrone, R. Di Giovambattista, G. Cianchini and A. Piscini | | | Istituto Nazionale di Geofisica e Vulcanologia | | | The last solar minimum (2007-2009) has been considered to identify anomalous behaviours of electron density variations in relationship with geomagnetic Ap and AE indexes.
The variations of the ionospheric parameter foF2 from ionosonde , vTEC from GPS and electron density from CHAMP satellite Langmuir probe at Rome location are analysed. Each observed anomaly has been then associated to the related geomagnetic conditions: for each event, the values of the Ap index at the time when the anomaly is detected, and that for the previous 24 hours, are taken into account. The auroral electrojet index AE has also been investigated, considering its values up to 6 hours before the occurrence of the anomaly. A characterization of the observed electron density anomalies with respect to the related geomagnetic conditions, is here presented.
| | 4 | Ionospheric effects of the September 2017 space weather storm over Brazil | Damaceno, J et al. | p-Poster | | | Juliana G. Damaceno[1,2], Elvira Musicò1, Claudio Cesaroni[1], Luca Spogli[1,3], Marcin Grzesiak[3], Giorgiana De Franceschi[1], Massimo Cafaro[2] | | | [1]Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Rome, Italy; [2]University of Salento (UNISALENTO), Via per Monteroni, 73100 Lecce, Italy; [3]SpacEarth Technology (SET), Via di Vigna Murata 605, 00143 Rome, Italy; [4]Space Research Center of Polish Academy of Sciences (CBK-SRC), Bartycka 18A 00-716 Warsaw, Poland. | | | Geomagnetic storms can induce irregularities in the ionospheric electron density with consequent interference on GNSS signals. Such an effect, so-called scintillation, can lead to loss of lock, which has been already verified in Brazil and affects many activity fields, including petroleum-drilling ships, bringing economic losses.
In September 6, 2017 an X9.3 flare occurred, considered the strongest solar flare in more than a decade, producing severe geomagnetic storms on 7 and 8 September. In this work, different sources of data are used to analyse the ionosphere response in the Brazilian region during the event:
1. Plasma density at 2 Hz rate from Langmuir Probe on board of Swarm satellites;
2. Amplitude, phase scintillations and Rate of TEC (ROT) data from 7 multi-frequency multi-constellation Septentrio receivers deployed in Brazil at different latitudes ranging from 2°S to 30°S;
3. Ionograms from 5 digisondes over Brazil: CAJ2M, CGK21, FZA0M, SAA0K and SMK29;
4. Total Electron Content (TEC) from 143 geodetic dual frequency receivers of IBGE (Instituto Brasileiro de Geografia e Estatística) network.
The paper shows the results of the multi-instruments analysis of in-situ and ground based measurements, highlighting the behaviour of the scintillation indices captured along the southern crest of Equatorial Ionospheric Anomaly. Unusual high phase scintillations are found in contrast to low amplitude scintillations, as collocated with TEC gradients and in situ electron density fluctuations at LEO orbit, suggesting the formation of equatorial patches with scale size greater than the radius of the first Fresnel zone (Df).
| | 5 | Study of the impact of St. Patrick's 2013 and 2015 events on the midlatitude ionosphere over Europe | Alfonsi, L et al. | p-Poster | | | Haris Haralambous[1], Ashik Paul[2], Lucilla Alfonsi[3], Claudio Cesaroni[3], Christina Oikonomou[4], Sarbani Ray[2] | | | [1]Frederick University, Cyprus; [2]Institute of Radio Physics and Electronics, University of Calcutta, India; [3]Istituto Nazionale di Geofisica e Vulcanologia; [4]Frederick Research Centre, Cyprus | | | The geomagnetic storms on March 2013 and 2015 present similar features though they have different intensities. They were both induced by a Coronal Mass Ejection (CME) and commenced at approximately the same time (5 UT). Their main phase peaked at the same time (21-22 UT) and was marked with two minima of the Dst ring current index which occurred at almost same moments (around 10 UT and 22 UT). Their response to ionosphere demonstrated a hemispheric asymmetry with a most prominent negative storm effect in the Northern Hemisphere (Kalita et al. 2016, Liu et al. 2016a). In this study we use manually scaled data of ionospheric characteristics (foF2-hmF2) from European Digisonde stations at Arenosillo (Spain) (37.10°N, 353.30°E), Athens (Greece) (38.00°N, 23.50°E), Chilton (UK) (51.50°N, 359.40°E), Ebre (Spain) (49.93°N, 0.50°E), Juliusruh (Germany) (54.60°N, 13.40°E), Moscow (Russia) (55.47°N, 37.30°E), Pruhonice (Czech Republic) (50.00°N, 14.60°E) and Rome (Italy) (41.80°N 12.50°E) and vertical Total Electron Content (vTEC) from collocated dual-frequency GNSS stations. In addition we exploit TEC maps over Europe to underline the similarity in the temporal characteristics exhibited over Europe in the two events. In particular we show that during the first day of both storms strong electron density depletions are observed over Northern Europe without such effect being visible in the Southern European part. This behavior is related to the extension of the mid-latitude trough towards lower European latitudes. | | 6 | On the characterization of density fluctuations using Swarm data | D'amicis, R et al. | p-Poster | | | Raffaella D'Amicis, Stephan Buchert, Lorenzo Trenchi, Enkelejda Qamili, Daniele Telloni, Sharon Aol, Thomas Nilsson | | | | | | In this study we propose to apply time series analysis of Swarm LP data to characterize the ionospheric turbulence in irregularities. In particular we will study spectral properties of density fluctuations and perform a multifractal analysis with the aim to extract Space Weather relevant parameters and statistics from the data.
Different conditions will be analyzed focusing in particular on the comparison between quiet and disturbed periods. | | 7 | An entropic analysis of the polar cap current systems | D'angelo, G et al. | p-Poster | | | Giulia D’Angelo[1], Mirko Piersanti[2], Massimo Materassi[3] | | | [1]Università degli studi “Roma Tre”, Rome, Italy; [2]National Insitute of Nuclear Physics, University of Rome Tor Vergata, Rome, Italy; [3]Institute for complex systems ISC-CNR, National Research Council, Florence, Italy | | | Birkeland currents (field-aligned currents - FACs) flow along magnetic field lines to connect magnetospheric current systems to the high latitudes ionospheric currents. Within the polar cap, tail-shape magnetic field lines are tilted antisunwards by the flow of the solar wind, whereas in the return flow region field lines are tilted sunwards due to pressure from the magnetotail driving the sunwards convection of closed flux. At the polar cap boundary (PCB), the opposite bend-back of the field lines on either side of this convection reversal produces a shear in the magnetic field that is associated with a current flowing upwards or downwards. These currents, out of the ionosphere at the dusk PCB and opposite at dawn, are known as region 1 (R1) currents and connect with the cross-field currents at the magnetopause (the dynamo) and in the ionosphere (the load). Similar shears exist at the equator edge of the convection pattern, and the associated region 2 (R2) FACs flow out of the ionosphere at dawn and into the ionosphere at dusk. These FACs are flowing along magnetic field lines, which map to the inner magnetosphere where they enhance the nightside portion of the ring current, named the partial ring current. The aim of the current paper is to review the processes that give rise to current variability on timescales of hours and minutes in response to changes in the interplanetary medium during the March 2015 and June 2015 Geomagnetic storms. To do so, we will describe the behaviour of the field-aligned currents (FACs) that flow into and out of the ionosphere in the polar cap regions, observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). Through an entropy analysis, we found a new polar cap current system directly driven by the SW which connect the northern hemisphere to the southern hemisphere. | | 8 | Geomagnetically induced currents during the September 6, 2017 Geomagnetic storm. | Di matteo, S et al. | p-Poster | | | Simone Di Matteo[1,2], Mirko Piersanti[2,3], Brett Carter[4], Giulia D'Angelo[5], Julie Currie[4], Endawoke Yizengaw[6], Umberto Villante[2] | | | [1]Department of Physical and Chemical Sciences, University of L’Aquila, Italy; [2]Consorzio Area di Ricerca in Astrogeofisca, L’Aquila, Italy; [3]INAF, Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy; [4]SPACE Research Centre - RMIT University , Melbourne, Australia; [5]Department of Mathematics and Physics, University of “Roma Tre”, Italy; [6]Institute for Scientific Research, Boston College, Boston, Massachusetts, USA. | | | The space environment near Earth, is constantly subjected to changes in the solar wind flow generated at the Sun. Examples of effects resulting from this variability are the occurrence of powerful solar disturbances, such as coronal mass ejections (CMEs). The impact of CMEs on the Earth’s magnetosphere perturbs the geomagnetic field causing the occurrence of geomagnetic storms. Such extremely variable geomagnetic fields trigger geomagnetic effects measurable not only in the geospace but also in the ionosphere, upper atmosphere, and on the ground. For example, during extreme cases, rapidly changing geomagnetic fields generate intense geomagnetically induced currents (GICs). In recent years, GIC impact on the power networks at middle and low latitudes has attracted attention due to the expansion of large-scale power networks into these regions.
In this work we analyzed the magnetospheric and ionospheric response to the September 6, 2017 Geomagnetic Storm by reconstructing the global ionospheric current flow pattern through the use of the Piersanti et al. [2016] model and by evaluating the correspondent GIC. The study also indicated that the eastward component of the geoelectric field is dominant for low-latitude locations during the SSC events. | | 9 | Seasonal effect of thermospheric response to geomagnetic storms | Bounhir, A et al. | p-Poster | | | Aziza Bounhir[1,2], Zouhair Benkhaldoun[1], Jonathan J. Makela[3], Mohamed Kaab1, Brian Harding[3], Daniel J. Fisher[3], Khaoula Elbouyahyaoui[1], Amal Loutf[1], Abdeladime El Fakhiri[1] and Ahmed Daassou[1] | | | [1]High Energy Physics and Astrophysics Laboratory, Oukaimeden Observatory, Cadi Ayyad University, Marrakech, Morocco; [2]High Energy Physics and Astrophysics Laboratory, Faculty of Sciences and Techniques, Marrakech, Morocco; [3]Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Illinois 61801, USA, Urbana, IL, United States. | | | This paper presents the seasonal effect of the thermospheric response to geomagnetic storms. The studied area is the western part of north Africa. The data are the winds and temperature delivered from a Fabry-Perrot interferometer (FPI), installed at Oukaimeden Observatory (31.21°N, 7.87°W, 22.84°N magnetic). By observing the 630 nm airglow at an altitude of approximately 250 km, the FPI delivers the meridional winds; North and South line of sight (LOS) measurements and the zonal winds; East and West LOS measurements. Three years of data are considered, from 2014 to 2016. The data have been separated into geomagnetically quiet (3 hours Kp < 3) and active nights (3 hours Kp > 3). The storm time winds depart from their climatological behavior in a variety of ways depending mainly on the season, the magnitude of the storm, the time of the storm and whether the storm is associated with a Traveling Atmospheric Disturbance (TAD) or not. Even though, every storm is unique the seasonal average exhibits some interesting features. The seasonal disturbed winds and temperature, which consist of the storm time data seasonal average minus quiet time data seasonal average, have been analyzed. In all seasons, we can see equatorward storm surges and trans-equatorward surges in the meridional disturbed winds. These surges are the lowest in winter time (~ ±10 m/s) and are high in Autumn and summer time (~ -60 m/s and 40 m/s). The seasonal disturbed zonal winds are westward in all seasons with the highest amplitude (~100 m/s) in autumn time and the lowest in winter time (~10 m/s). The seasonal disturbed temperature is high in autumn (~ 280 K) and low in winter (~ 50 K). In summer and winter time, the seasonal disturbed temperature seems to be modulated. | | 10 | Surprising phenomenon in ionospheric response to geomagnetic storm of 15 August 2015 | Lastovicka, J et al. | p-Poster | | | Jan Lastovicka[1], Ilya Edemskiy[2] | | | [1] Institute of Atmospheric Physics CAS, Prague, Czech Republic. [2] Institute of Solar-Terrestrial Physics, Irkutsk, SB RAS, Russia. | | | The ionospheric response to geomagnetic storm of 15 August 2015 exhibited an unexpected phenomenon, a localized TEC enhancement (LTE) in the form of two separated plumes, which peaked southward of South Africa. The plumes were first observed at 5 UT near the southwestern coast of Australia. The southern plume was associated with local time slightly after noontime (1-2 hours after local noon). The plumes moved with the Sun. They peaked near 13 UT southward of South Africa. The southern plume kept constant geomagnetic latitude (63-64oS); it persisted for about 10 hours, whereas the northern plume persisted by about two hours more. Both plumes disappeared over the South Atlantic Ocean. No similar LTE event was observed during the prolonged solar activity minimum period of 2006-2009. In 2012-2016 we detected altogether 26 LTEs and all of them were associated with the southward excursion of Bz. The negative Bz excursion seems to be the necessary but not sufficient condition for the LTE occurrence. The LTE seems to be a new ionospheric space weather phenomenon. | | 11 | Development of an operational prototype for the determination of the thermospheric density on the basis of a coupled thermosphere-ionosphere model | Lalgudi gopalakrishnan, G et al. | p-Poster | | | Ganesh Lalgudi Gopalakrishnan[1], Michael Schmidt[1], Florian Seitz[1], Kristin Vielberg[2], Juergen Kusche[2], Klaus Boerger[3] | | | [1] Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM), [2] Institut für Geodäsie und Geoinformation (IGG), Bonn, [3] German Space Situational Awareness Centre (GSSAC), Uedem | | | The German Space Situational Awareness Centre (GSSAC) has been authorized by the German Federal Ministry for Defense (BMVg) and the Federal Ministry of Economics and Energy (BMWi) to provide services regarding the space situational awareness. Besides space weather GSSAC focuses on the collision and the re-entry of objects such as Low-Earth-Orbiting (LEO) satellites and space debris. With respect to the determination and propagation of the trajectories of LEO objects, the thermospheric drag is of particular importance, since it is the most important deceleration effect within the object’s equation of motion. Today, the calculation and prediction of the thermospheric drag are usually carried out by empirical thermosphere models such as the Jacchia-Bowman model JB2008, the COSPAR International Reference Atmosphere model CIRA86 or the Drag Temperature Model DTM2013. These models are amongst other quantities, driven by globally defined space weather parameters such as the F10.7 (reflecting solar activity) and the Kp (reflecting magnetic activity) indices.
Investigations showed recently that these empirical models provide rather different values, in particular in case of stronger space weather events. For a better understanding and modelling of the thermospheric drag, an improved knowledge of the highly variable external driving parameters is required. For that purpose the coupled thermosphere-ionosphere (TI) processes have to be considered, which describe the interaction of the neutral density of the thermosphere with the electron density of the ionosphere.
The main objective is the representation of the thermospheric density as a function of the ionospheric electron density considering the TI processes. Recently, it was verified that solar events influence both satellite accelerometer measurements and measurements of the Total Electron Content (TEC) of the ionosphere. Consequently, both measurement types should be correlated with space weather events. Following this totally new and promising concept a heuristic model of the thermospheric drag as a function of the electron density including a prediction part for operational use will be developed.
In this contribution we will present the basic ideas and selected preliminary results on the methods used and parameterization for the analysis of TI coupling. | | 12 | Ionospheric ion response to the space weather event during 6-8 September 2017 | Yamauchi, M et al. | p-Poster | | | A. Schillings[1,2], M. Yamauchi[1], H. Nilsson[1], T. Sergienko[1], C.-F. Enell[3], R. Slapak[3], P. Wintoft[1], M. Wik[1], M.G. Johnsen[4], I. Dandouras[5] | | | [1]Swedish Institute of Space Physics (IRF), Sweden, [2]Division of Space Technology, Lulea? University of Technology, Kiruna, Sweden, [3]EISCAT Scientific Association Headquarter, Kiruna, Sweden, [4]Tromsø Geophysical Observatory (TGO), UiT the Arctic University of Norway, Tromsø, Norway, [5]Institut de Recherche en Astrophysique et Planétologie, CNRS and University of Toulouse, Toulouse, France | | | Recent studies of ionospheric ion escape show that the escaping ion flux from the polar region increases exponentially with Kp up to Kp=7, and even sharper for higher Kp, in contrast to only a factor of 2 difference between northward and southward IMF. The same non-a linear (exponential) dependence is also expected for energy extraction from the solar wind to the ionosphere by the mass-loading effect of these escaping ions. This indicates that the energy input to the polar ionosphere and relevant human impact during severe space weather events can be higher than what reconnection-based coupling function method predicts.
One immediate question is: which element of space weather events most significantly affects the ionospheric response among, e.g., enhanced UV, solar energetic particle (SEP) events, arrival of interplanetary coronal mass ejections (ICMEs), flux of trapped energetic particles in the inner magnetosphere (e.g., at geosynchronous orbit), strong interplanetary magnetic field (IMF), the main phase of major magnetic storm with enhanced ring current, severe substorms (AL < -2000 nT), and possible combinations of these elements. We here restrict our discussion to ion energization and subsequent outflow among many types of ionospheric responses. While past statistics showed clear correlation between the ion upflow and these potential factors, we need continuous monitoring to identify the most important external parameters that influences ionospheric ions and subsequent upflow.
The September 2017 event is an ideal event to study this problem because a series of X-flares occurring before two ICMEs separated by one day, where the first had northward IMF on arrival, and the second had southward IMF arrival, with only the second one causing a severe substorm with AL < -2000 nT and a geomagnetic storm. The season is also ideal because Cluster covers the cusp region (the main route of the ion escape) only near equinoxes (in this sense October-November events 2003 were not optimal). EISCAT Svalbard radar was located near local noon (cusp) when the X9.2 solar flare took place on 6 September, and near local midnight when two ICMEs accompanied by flux enhancements of energetic particle in the solar wind arrived on 7 September and 8 September.
We show observations by Cluster and EISCAT. Both Cluster and EISCAT results during this event strongly suggest that high flux of energetic particles in the solar wind or ICME arrival causes more directly influence the ionospheric heating and upflow than sudden increases of EUV flux by the X-flare or southward turning of the IMF direction.
| | 13 | Ionospheric response to strong geomagnetic storms from 2017 analysed on the basis of the LOFAR data. | Matyjasiak, B et al. | p-Poster | | | Barbara Matyjasiak, Mariusz Pożoga, Marcin Grzesiak, Hanna Rothkaehl, Beata Dziak-Jankowska, Łukasz Tomasik, Dorota Przepiórka | | | Space Research Centre of the Polish Academy of Sciences | | | During 2017 several strong geomagnetic storms took place as a response to the major solar events. One of them, and the biggest one, was severe G4 storm following the solar flare classified as X9.3 which occurred on the 8th of May.
Earlier in the year another intense geomagnetic storm took place which was caused by a low-intensity (B4.4) solar flare from May 23. Storm was unexpectedly strong (type G3) and delayed in relation to the preceding flare.
Such intense events may lead to a very rapid and unpredictable changes in the ionospheric conditions and may affect performance of many technologies such as: radio communication, satellite positioning, power lines, etc., and thus have an impact on our day to day life.
Using LOFAR interferometer data and dedicated tooling for ionospheric parameters analysis, we present here study of the local ionospheric conditions during mentioned two strong geomagnetic storms in terms of ionospheric structures motion and sizes. The analysis of changes in scintillation level during the period of geomagnetic disturbances, which is a measure of radio signal fluctuations is also presented.
In our work we are using data obtained from LOFAR interferometer core stations placed in the Netherlands. | | 14 | TEC dependence on different Space Weather parameters in Mexican region | Sergeeva, M et al. | p-Poster | | | Maria Sergeeva[1,2], Olga Maltseva[3], Juan Americo Gonzalez-Esparza[2], Pedro Corona-Romero[1,2] | | | [1] CONACYT, Instituto de Geofisica, Unidad Michoacan, UNAM, Mexico; [2] SCiESMEX, Instituto de Geofisica, Unidad Michoacan, UNAM, Mexico; [3] Institute for Physics, Southern Federal University, Russia | | | Space Weather (SW) impact on variations of ionospheric Total Electron Content (TEC) can be estimated with use of different SW parameters. Three groups of these parameters were used in this study: (1) solar activity indices solar radio flux at 10.7 cm (F10.7) and Lyman Alpha Solar Index (Lα), (2) geomagnetic field indices Dst and Kp and (3) interplanetary magnetic field intensity (IMF) and satellite measured proton density (Np). The relationship between these parameters and TEC was estimated by correlation coefficients (R). On-hour TEC data were derived from JPL global ionospheric map for Mexico City coordinates (19.3°N, 99.1°W). Daily averaged SW parameters were freely obtained via Internet from OMNI base. The period under analysis was between 2001 and 2017. The attempt to reveal the parameters with higher correlation was made. The preliminary results are as follows. During the years of high solar activity (2001-2002) R between TEC and F10.7 and Lα coincide. R values were maximal at (9-11)LT and (20-21)LT, though the correlation itself could be not very high. During the minimum of solar activity, TEC was more correlated to F10.7 than to Lα in 2006 and was less correlated to F10.7 than to Lα in 2009. The highest excess of correlation to Lα over the correlation to F10.7 was observed in 2014. R between TEC and geomagnetic indices during high solar activity are rather uniform and had the values of R=(04.-0.6) with little difference between Kp and Dst, showing the constant readiness of the ionosphere to respond to disturbances. During the years of minimum activity, R had its maximal value about 0.6 near (12-14)LT and rather low values (about 0.2) during the rest of the time. For the third group of SW parameters, it was found that TEC dependence on IMF had a similar character as its dependence on Kp. R for Np was mostly much less than for IMF and was near zero. The obtained results provide the qualitative estimate for each SW parameter influence in TEC variations. | | 15 | Solar terminator and corresponding variability within ionospheric plasma | Koucká knížová, P et al. | p-Poster | | | Petra Koucká Knížová, Kateřina Potužníková, Daniel Kouba, Josef Boška, Zbyšek Mošna, Dalia Obrazová | | | Institute of Atmospheric Physics, Czech Academy of Sciences, Department of Aeronomy, Boční II/1401, 141 31 Czech Republic | | | The Ionosphere is highly variable system that shows oscillations on wide range of scales. Observed wave-like disturbances are caused by variety of sources from above and below. Sun and magnetosphere are considered to the most important drivers. However, the forcing from below by processes in the lower-laying atmospheric regions cannot be omitted. The oscillation within ionospheric plasma can be detected on a broad scales ranging from acoustic and gravity waves to oscillations on periods corresponding to solar cycles.
Within the ionospheric variability, the Acoustic-Gravity Waves (AGW) play an important role. They are present in the atmosphere and ionosphere all the time and their attribution to the particular source still remains an open task. The AGWs, their sources, persistence, propagation, are systematically studied since sixties last century.
Solar Terminator has been identified as an important source of AGW in the Earth atmosphere-ionosphere system. The cooling/heating of the Earth’s atmosphere induced by decrease/increase of the incoming solar radiation is a potential generator of the wave/like disturbances that are likely to propagate through the atmosphere-ionosphere system. Due to the systematic occurrence of AGWs during sunrise and sunset, it has been proven experimentally, that the moving region of atmospheric constituents with large gradients acts a source of AGW structures. However, the variability in periodicity and persistence of AGWs is very large and the observational techniques limited. The presentation focuses on Solar Terminator and related ionospheric variability as observed by ground based measurements in Midlatitudes |
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