Session SWR5 - Geomagnetic Activity on Earth's Surface and Effects on Ground-Based Technological Systems

Audrey Schillings, onsite (Department of Physics, Umeå University, Umeå, Sweden), Liisa Juusola, online (Finnish Meteorological Institute, Helsinki, Finland), Chigomezyo Ngwira, online (Orion Space Solutions, Louisville, USA)

Solar activity influences the terrestrial environment and can cause geomagnetic activity that induce electric fields in the conducting ground. The geoelectric field on Earth’s surface, in turn, drives geomagnetically induced currents (GIC) in conductor networks. Several reports have highlighted the vulnerability of our high-tech society to GIC and the need for a better understanding of space weather events that drive them.
We invite poster and oral contributions on recent advances in the understanding the causes and consequences of GIC from a scientific point of view. The session will be dedicated to space weather events and geomagnetic activity related to GIC in ground-based technological systems and forecasts using various models.
The session will especially focus on:
- Rapid geomagnetic variations associated with solar wind-magnetospheric-ionospheric processes during quiet and disturbed times (SuperMAG, INTERMAGNET, IMAGE, and others)
- Response of earth’s magnetic field to space weather events (SWARM, CHAMP, ePOP and others)
- GIC due to extreme space weather events
- Nowcasting/forecasting of space weather events
We particularly encourage contributions related on rapid magnetic field variations associated to substorm currents, Kelvin-Helmholtz instabilities, Omega bands and others.

Poster Viewing
Monday October 24, 09:00 - 14:00, Poster Area

Talks
Tuesday October 25, 15:45 - 16:45, Fire Hall
Tuesday October 25, 17:00 - 18:00, Fire Hall

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Talks : Time schedule

Tuesday October 25, 15:45 - 16:45, Fire Hall

15:45	Fast moving auroral structures as a cause for large GIC	Apatenkov, S et al.	Invited Oral
	S. Apatenkov[1,2], D. Sheveleva[2], E. Gordeev[2], Ya. Sakharov[3], V. Selivanov[4]
	[1]Harbin Institute of Technology, Harbin, People's Republic of China; [2]Saint Petersburg State University, St. Petersburg, Russia; [3]Polar Geophysical Institute, Apatity, Russia; [4]Kola Science Centre, Russian Academy of Sciences, Apatity, Russia
	We identified the auroral structures associated with large geomagnetically induced currents (GIC). In total 140 one hour intervals with the largest GIC were selected at the station Vykhodnoy (Kola Peninsula, 65 MLat) during 2012-2018. For a subset of 97 events, auroral observations from low-altitude DMSP/SSUSI were available for analysis. As a result, in 32% of cases we detected auroral omega structures within one MLT hour of GIC observations. In the morning sector 01-07 MLT, more than 80\% of GIC events were associated with omega structures. Thus, we managed to preliminary classify ionospheric current systems that cause a significant part of extreme GIC events. The spatial motion of those currents in the ionosphere is shown to be responsible for GIC. We found the propagation velocities of omega structures based on magnetic observations to be 0.5-3 km/s that is larger than previously reported values.
16:00	Investigation of ionospheric and ground level signatures of space weather over Turkey	Gülay, E et al.	Oral
	Ezgi Gülay[1], Zerefşan Kaymaz[1], Emine Ceren Kalafatoğlu Eyigüler[2]
	[1]Istanbul Technical University
	In this study, we present our preliminary results of the investigation of ionospheric and ground-level signatures of space weather over Marmara region in Turkey. In our study, we use ionospheric electron density measurements using Dynasonde measured in ITU Campus, Istanbul (41°N, 29°E), magnetic field measurements in İznik (40.43°N, 29.72°E) and magnetotelluric measurements of magnetic field and electric field in Bozcaada (37.5°N, 106°E). For the selected geomagnetic storms, measurements are used to search for signatures of geomagnetically induced currents (GICs) and their relation with the ionospheric variations. Deviations from the quiet days are investigated for ionospheric electron density, geomagnetic field and electric field. Statistical analysis has been conducted to find out the general behavior of geomagnetic field and ionosphere during the geomagnetically disturbed days over mid-latitudes. Additionally, interplanetary magnetic field (IMF) and dynamic pressure of solar wind have been statistically studied. Time derivative of the horizontal geomagnetic field has been utilized to show the GIC presence in mid-latitudes. At the meeting, we will present our first results based on our measurements and discuss the physical causes of the variations observed.
16:15	Monitoring the ionospheric polar electrojet boundaries and impact on GNSS disturbances	Eldor, M et al.	Oral
	Marie Vigger Eldor
	DTU Space, The Technical University of Denmark
	During magnetospheric substorms a strengthening of the westward polar electrojet (PEJ) can be observed in magnetic data from ground stations in the Arctic region. The electric currents of the PEJ produces magnetic signals which may correlate with disturbances in positioning and navigation systems. In this presentation I will show how modelling the ionospheric PEJ during substorms can contribute to the understanding of space weather effects on GNSS signals. The presentation will be based on the analysis of 1 Hz ground magnetometer data from the west coast of Greenland. During a substorm a sudden and sharp decrease in the horizontal magnetic field variation H, derived from the magnetometer data, can be observed. The magnetic data are used to develop a model of the magnetic field components. This model estimates the ionospheric sheet current density at the magnetic latitudes 55-85 degrees. The electric currents in the ionosphere are modelled as infinite long line-currents located at a height of 115 km above ground and separated by 1 degree in latitude. I will show how the ionospheric sheet current density can help to determine the PEJ boundaries and how the strength is correlated to the phase scintillation index (sigma phi) measured in GNSS over Greenland during high geomagnetic activity.
16:30	Large and localized geomagnetic disturbances at mid-latitudes: the double H-spike	Guerrero, A et al.	Oral
	Antonio Guerrero [1], Elena Saiz [1], Consuelo Cid [1]
	[1] Universidad de Alcalá, Space Weather group, Spain
	Extreme space weather events, like the Carrington and the Halloween ones, share some common features seen on individual magnetometers that global geomagnetic indices like Dst (or SYM-H) indices do not show. They feature high intensity (hundreds of nT) and relatively short duration (within one or two hours); consequently, they are one of the most dangerous triggers for ground technology failures as drivers of GIC. These extreme features have been identified in previous works and named H-spikes. In this work we present the same type of features seen as a double H-spike for more moderate events as seen by mid-latitude magnetometers and their relationships to substorm using SuperMAG databases.

Tuesday October 25, 17:00 - 18:00, Fire Hall

17:00	Geomagnetically Induced Currents and Harmonic Distortion Monitoring using VLF Observations	Clilverd, M et al.	Oral
	Mark A. Clilverd*[1], Craig J. Rodger[2], James B. Brundell[2], Michael Dalzell[3], Ian Martin[3], Daniel H. Mac Manus[2], and Neil R. Thomson[2]
	[1]British Antarctic Survey (UKRI-NERC), Cambridge, United Kingdom, e-mail: macl@bas.ac.uk; [2]Department of Physics, University of Otago, Dunedin, New Zealand; e-mail: craig.rodger@otago.ac.nz; [3]Transpower New Zealand Limited, Wellington, New Zealand, email: Michael.Dalzell@transpower.co.nz, Ian.Martin@ems.co.nz
	Several periods of large Geomagnetically Induced Currents (GIC) have been detected in the Halfway Bush substation in Dunedin, South Island, New Zealand, since 2017. The substation initially included the single phase transformer T4 and 3-phase transformer T6, but more recently the single phase unit has been removed. GICs lead to half cycle transformer saturation and is one of the few ways in which even-order harmonics are produced in a well run power transmission network. Using very low frequency (VLF) wideband measurements to detect the presence of power system harmonics we show how even-order power system harmonics can be used to monitor "stressed" network transformers, with the observations made remote from the substation itself [1]. VLF receiver systems have picked up harmonics from the substation, up to the 30th harmonic. Despite large local variations in the amplitude of substation harmonics, and the reconfiguration of the substation transformer setup, a simple algorithm has been developed to identify periods of GIC-induced harmonic enhancements, with the anticipation that the test could be used for nowcasting of stressed transformer conditions. Details regarding the VLF observations, harmonics algorithm development, and inferences in relation to GIC susceptibility will be discussed. Reference: Clilverd, M A, C J Rodger, J B Brundell, M Dalzell, I Martin, D H Mac Manus, and N R Thomson, Geomagnetically Induced Currents and Harmonic Distortion: High time Resolution Case Studies, Space Weather, 18, e2020SW002594, doi:10.1029/2020SW002594, 2020.
17:15	Real-time forecasting of geomagnetic conditions using the Gorgon global magnetosphere model	Eggington, J et al.	Oral
	Joseph Eggington[1], Mike Heyns[1], Martin Archer[1], Christopher Cave-Ayland[1], Jeremy Chittenden[1], Ravindra Desai[1], Jonathan Eastwood[1], Harley Kelly[1], Lars Mejnertsen[1], the SAGE Consortium, the VSWMC Consortium
	[1]Imperial College London, UK
	Severe space weather poses a major risk to society, which can be mitigated by accurate forecasting of the near-Earth space environment. Global magnetohydrodynamic (MHD) simulations are a powerful tool for achieving this, as they provide explicit modelling of the magnetosphere-ionosphere system faster than real-time. Coupling these simulations with either live upstream solar wind monitor data or solar wind predictions from a first-principles heliospheric model provides increased forecasting lead-times, allowing for more effective implementation of mitigation strategies for end-users. One example of such a tool is Gorgon, a global magnetospheric MHD model developed at Imperial College London, which is being deployed operationally for the UK context as part of the SWIMMR Activities in Ground Effects (SAGE) consortium, aimed at end-users affected by geomagnetically induced currents. Here we demonstrate Gorgon’s ability to simulate space weather events in real-time by driving with live upstream solar wind data and discuss key optimisations of the model for ground effects forecasting, such as specialised grid geometries and multiple approaches for estimating the ground geomagnetic field which include ground conductivity. The code is validated by comparing predictions of past geomagnetic storms against local observations, global geomagnetic indices and other key metrics. We also discuss the integration of an optimised version of Gorgon at ESA’s Virtual Space Weather Modelling Centre (VSWMC), and show initial extended lead-time results from an example Gorgon run which captures the magnetospheric response to a coronal mass ejection simulated by the EUHFORIA heliospheric model. Finally, with a focus on the wider end-user community within Europe, we present additional forecasting outputs such as regional geomagnetic indices and relevant benchmarks (e.g. Joule heating) being developed as part of an ongoing ESA magnetospheric modelling project.
17:30	GIC extreme storm modelling in New Zealand	Mac manus, D et al.	Oral
	Daniel H. Mac Manus[1], Craig J. Rodger[1], Michael Dalzell[2], Andrew Renton[2], Tanja Petersen[3], Gemma S. Richardson[4], and Mark A. Clilverd[5]
	[1]Department of Physics, University of Otago, Dunedin, New Zealand; [2]Transpower New Zealand Limited, Wellington, New Zealand; [3]GNS Science, Lower Hutt, New Zealand; [4]British Geological Survey (UKRI-NERC), Edinburgh, UK; [5]British Antarctic Survey (UKRI-NERC), Cambridge, UK.
	During Space Weather events, geomagnetically induced currents (GICs) can be induced in high-voltage transmission networks. Damage and disruption has occurred during some “large” geomagnetic disturbances over the last ~25 year; significantly more impact is expected during a future “extreme” geomagnetic disturbance. A transformer-level representation of the transmission network in New Zealand has been developed, with detailed DC resistances provided by our partners from the national grid operator. The network representation has been combined with a thin-sheet conductance model using a layered resistivity structure to calculate electric fields; thus the magnitude of the GIC can be determined. Calculated outputs have been validated against GIC observed at ~70 transformers during multiple geomagnetic disturbances since 2001. We suspect the extreme storm modelling with industry provided power grid information used in a network model validated by multiple years of GIC observations is uniquely possible to New Zealand, likely providing many new insights. Our national grid partners have provided us with five different "danger threshold" levels of mean currents across differing time periods. These numbers vary depending on the style of the transformer: single phase, 3-phase 3 limb, and 3-phase 5-limb. Our partners have identify transformer types across the network, such that we can better determine the risk across the electrical network during an extreme storm. We investigate the GIC expected for worst-case extreme geomagnetic storm intended to be on the order of the 1859 Carrington event. We use multiple geomagnetic field variations with time as the model input, to represent uncertainties in the variability during an extreme storm. These time variations come from observed geomagnetic storms, scaled up to "extreme" amplitudes. This is combined with multiple latitude variations to simulate the variation in magnetic field across the transmission network. The results show reoccurring locations (i.e. transformers in specific stations) with GICs, indicating regions where mitigation efforts should be focused. Importantly, we find the "hotspot" sites range across the entire of New Zealand. In an attempt to keep the network operational mitigation plans are being developed to reduce GIC at transformers identified to be at elevated risk. These mitigation planning efforts will be informed by the extreme storm modelling that we will concentrate on in the current presentation.
17:45	Real-time challenges for space weather predictions: October-November 2021 solar and geomagnetic events for Scandinavia	Wintoft, P et al.	Oral
	Peter Wintoft [1], Magnus Wik[1], Ari Viljanen [2], Magnar G. Johnsen [3], Kristian Solheim Thinn [4], Luciano Rodriguez [5]
	[1] Swedish Institute of Space Physics, [2] Finnish Meteorological Institute, [3] Tromsø Geophysical Observatory, [4] SINTEF Electric Power Technology, [5] Royal Observatory of Belgium
	Solar active regions provide the first signs of upcoming space weather. Ultimately, models should predict flares and CMEs hours or days in advance. At the onset of solar storms, flares are detected and later CMEs are observed. Of crucial importance is the determination of CME properties. From that point, there are currently no real-time observations until the detection at L1 monitors, and therefore one must rely on models. Using L1 measurements many models exist that predict magnetospheric phenomena with lead times of 30 minutes to a few hours. When a space weather situation plays out in real-time many data sources from Sun to Earth must be consulted to form a comprehensive view that should have value to an end user. In this work we describe the challenges in providing predictions and warnings for the events that took place during Oct-Nov 2021. The first signs of risk for solar storms appeared during 22 Oct when active region (AR) 12887 rotated into view, followed by AR 12891 on 28 Oct. The regions produced multiple M-flares and one X-flare (12887) and several CMEs. The two most important CMEs occurred on Oct 28 (AR 12887) and Nov 2 (AR 12891), where only the latter caused significant geomagnetic activity peaking at G4 on Nov 4. The ground magnetic field had largest dB/dt late on Nov 3 in northern Scandinavia and with continued large disturbances during Nov 4. Further south the dB/dt magnitude decreased but now with peak activity on Nov 4, coinciding with the time of the G4. A transformer disconnected in the Norwegian power grid during peak dB/dt on Nov 3. We present GIC measurements from the neighbouring transformer station and model calculations of GIC in the Nordic power grid during the event. Using real-time solar observations (SDO, STEREO-A, SOHO, GOES), JSOC/SHARP parameters, SIDC/CACTUS automatic CME detection, and SWPC/MetOffice ENLIL predictions we provided warnings that in many cases contradicted the warnings provided by SWPC, highlighting the challenge in providing warnings to end users. On Nov 3 we did however warn for the possibility of G4 either late on Nov 3 or during Nov 4. This resulted in that the Swedish power grid operator cancelled routine maintenance work during Nov 4 due to risk of interference from GIC. We will discuss the available resources and the difficulties in providing real-time predictions, and also how occurrence rates of solar storms versus geomagnetic storms have consequences on the warning system.

Posters

1	Signatures of wedgelets over Scandinavia during the St Patrick’s storm 2015	Schillings, A et al.	Poster
	Audrey Schillings[1,2], L. Palin[3], H.J. Opgenoorth[1], M. Hamrin[1]
	[1] Umeå University, Umeå, Sweden, [2] University of Leicester, United Kingdom, [3] Toulouse, France
	During solar cycle 24, one of the biggest storm occurred on Mar, 17 2015. Several thermospheric and ionospheric disturbances were reported in the literature. The perturbations in the ionospheric current system can be investigated through the ionospheric equivalent currents (EQCs), which are calculated from ground magnetic field data and virtually represent the 2D ionospheric current at an altitude of 100 km. The EQCs serve as a proxy to the real ionospheric currents. In our study, we investigated the EQCs and differential EQCs at the early evening of Mar, 17 2015. Using data from IMAGE network with a 10 sec resolution, we looked at the spikes in northern component of the ground magnetic field. We found localized spikes over Scandinavia and at various time. A more detailed analysis showed that localized field-aligned current (FAC) system were building up to the pre-existing FAC system for a few minutes and then disappearing. This process was observed 3 times within 30 min and at different location. We suggest that these small and localized FAC systems are 3 independent wedgelets and potentially contribute to the development of the substorm following these observations. Our findings shows the importance of small-scale and localized ionospheric features and may want to be considered in the models of GICs forecasts and space weather events.
3	GEOINDUCED CURRENTS DURING SUPERSUBSTORMS AND INTENSE SUBSTORMS IN SEPTEMBER 2017	Setsko, P et al.	Poster
	Pavel Setsko[1], Irina Despirak[1], Yaroslav Sakharov[1], Vladislav Bilin[1], Vasiliy Selivanov[2]
	[1]Polar Geophysical Institute, Apatity, Russia; [2]Northern Energetics Research Centre Kola Science Centre RAS, Apatity, Russia
	Geoinduced currents (GIC) that occur in electrical networks, in gas and oil pipelines, can have a negative impact on their working up to accidents. One of the important sources of GIC in the auroral zone is the amplification and motion of electrojets during substorms. For analysis we selected one from extremely active space weather periods with multiple events – September 2017. Two intense (SYM-H peak ≤ −100 nT) and two moderate (−50 nT ≥ SYM-H > −100 nT) geomagnetic storms were developed, and one high-intensity long-duration continuous auroral electrojet activity (HILDCAA) event was observed. At the background on these complicated interplanetary and geomagnetic conditions, several intense substorms and two supersubstorms (SSS) were registered. Substorms with very high SML and AL indices (< -2500 nT) were called supersubstorms. The paper analyzes the thin spatiotemporal structure of electrojet development during substorms using the latitudinal profiles of the equivalent currents of the MIRACLE system and IMAGE magnetometers data compares it with GIC data in the North-West of Russia (eurisgic.ru) and in the South of Finland. It was shown that the appearance of GIC at different latitudes is associated with the movement of the westward electrojet to the pole during expansion phase of substorm. The paper also shows a relationship between an increase in the geomagnetic indices IL and Wp and the appearance of GIC, which also indicates the dependence of the appearance of GIC on substorm activity. The authors are grateful to the creators of the OMNI (http://omniweb.gsfc.nasa.gov), SuperMAG (http://supermag.jhuapl.edu/), IMAGE (http://space.fmi.fi/image/) databases for their use in the workplace. The work of Setsko P.V., Despirak I.V., Bilin V.A. was funded by RFBR and NSFB, project number 20-55-18003. The work of Sakharov Ya.A. and Selivanov V.N. on registration of the GIC was supported by the Russian Science Foundation project number 22-29-00413.
5	Assessing the risk from Geomagnetically Induced Currents to individual transformers of the Spanish power network	Marsal, S et al.	Poster
	S. Marsal[1], J.M. Torta[1], P. Piña-Varas[2], V. Canillas-Pérez[1], J. Ledo[2], A. Martí[2], P. Queralt[2], À. Marcuello[2], J.J. Curto[1]
	[1]Observatori de l’Ebre (OE), Univ. Ramon Llull - CSIC, Roquetes (Spain); [2]Institut Geomodels, Dept. Dinàmica de la Terra i de l’Oceà, Universitat de Barcelona, Barcelona (Spain).
	Geomagnetically induced currents (GIC), ultimately due to disturbed conditions in the Earth’s space environment caused by magnetic activity in the Sun, affect power transmission grid transformers differently depending on latitude, ground conductivity, transformer type and grid topology. We evaluate the risk from GIC threat to transformers as a product of hazard and vulnerability. Hazard evaluates the probability of occurrence of geoelectric fields, which in turn depends on the primary currents flowing above the site in question (e.g., mainly electrojets at auroral latitudes, magnetopause/ring current at midlatitudes), as well as on the local subsurface conductivity. On the other hand, the vulnerability of transformers depends on their winding resistances and on the network topology, which will favor GIC flow for certain orientations of the regional geoelectric field. Different vulnerability thresholds are assessed in terms of amps per phase, and the risk -understood as the probability of reaching these thresholds- in different transformers of the Spanish power network is evaluated based on magnetic observatory records of the period 2000 – 2021.
7	Geomagnetically Induced Currents and Harmonic Distortion: What we can learn from multiple years of THD observations across New Zealand?	Craig, R et al.	Poster
	Craig J. Rodger[1], Malcolm Crack[1], Ian Martin[2], Mark A. Clilverd[3], James B. Brundell[1], Daniel H. Mac Manus[1], and Michael Dalzell[2]
	[1]Department of Physics, University of Otago, Dunedin, New Zealand; [2]Transpower New Zealand Limited, Wellington, New Zealand; [3]British Antarctic Survey (NERC), Cambridge, United Kingdom
	Large geomagnetic storms are a known space weather hazard to power transmission networks due to the effects of Geomagnetically Induced Currents (GICs). Research in this area has been hampered in much of the world by a lack of GIC observations. Previous studies have noted that New Zealand is unusually fortunate in having a comparatively dense, high quality, set of GIC measurements, spanning >70 transformers in >20 substations. However, due to operational reasons these observations are clustered in the mid and lower South Island, giving a limited spatial sampling. GICs lead to half cycle transformer saturation and those currents are one of the few ways in which even-order harmonics are produced in a well run power transmission network. Hence even-order harmonic distortions are an alternative way to monitor the influence of GIC on transformers and identify "stressed" transformers. We have previously undertaken [1] a case study for 7-8 September 2017 showing how GIC effects can be monitored by using even harmonic distortion in locations where no GIC measurements are present (for example, most of New Zealand's North Island). We have gained access to ~8 years of total harmonic distortion (THD) measurements at over 350 circuit breakers made at over 120 separate substations spanning the North and South Islands, albeit with 10min time resolution. In this presentation we will discuss our findings from analyzing this data, with particular focus: on transformer locations with high GIC present (i.e., network hot spots), wider network changes, and the retirement of single phase transformers in multiple locations across the country. We also have access to high time resolution (1-5 s) magnetometer, GIC, and mains harmonic distortion data from the Halfway Bush substation in Dunedin. VLF radio wave data are used to provide high resolution measurements of mains harmonic distortion levels within the substation, using an antenna located by the fence. These high resolution observations near Dunedin are used to locally confirm our findings from the nationwide low time resolution data. [1] Rodger, C. J., et al., Geomagnetically Induced Currents and Harmonic Distortion: Storm-time Observations from New Zealand. Space Weather, 18, e2019SW002387, 2020. https://doi.org/10.1029/2019SW002387
8	Studies related on rapid magnetic field variations associated to substorms and storms	Asimopolos, N et al.	Poster
	Natalia-Silvia Asimopolos [1], Laurentiu Asimopolos [1]
	[1] Geological Institute of Romania
	Rapid magnetic field variations associated to storms, substorms and severe disturbances can interrupt the operation of the electric power system and other critical infrastructures whose installations are distributed over large areas, the most vulnerable components being overhead power lines and transformers. The interruption of the electricity supply has major consequences in all sectors of activity (transportation, communications, finance) as well as in the ability of government structures to intervene in emergency situations. As a result of this fact, concrete actions are needed to reduce this systemic risk generated by geomagnetic storms. In the background of a geomagnetic storm, the time variation of the geomagnetic field induces very low frequency currents, called induced geomagnetic currents (GIC). The intensity of the GIC depends on the characteristics of the geomagnetic field, on the resistivity of the soil in the area where the coupling of the field is made with the components of the electric power system, on the extension in space of the coupling area, on the way of treating the neutral of the network where the phenomenon occurs. The circulation of GIC in the system components produces abnormal operating regimes resulting, in most cases, in the disconnection of an important part of the affected network. It is obvious that the study of GIC can only be approached in a multidisciplinary way, both from a geophysical point of view (by measuring and modeling the geoelectric and geomagnetic field at the Earth's surface) and from an engineering energy point of view (by calculating and/or measuring in the affected electrical networks). The goal of this paper is to analyze the frequencies, intensity and time of occurrence of geomagnetic storms and the associated spectrum of geomagnetic field. Also, we set out to analyze the possibility of predicting these geomagnetic storms. The data used in this paper are acquired within the Surlari Observatory, and we obtained additional information to characterize the analyzed geomagnetic storms analyzed from specialized sites such as www.intermagnet.org and www.noaa.gov. Information about geomagnetic data from other observatories, as well as planetary physical parameters allowed us to perform comparative studies between the data recorded in different observatories. We have used in the numerical experiments a series of filtering algorithms, spectral and wavelet analysis with different mother functions at different level
9	Extreme geomagnetic storms in Northern Europe: modern events are far from the big one	Viljanen, A et al.	Poster
	Ari Viljanen [1], Elena Marshalko [1], Ilja Honkonen [1]
	[1] Finnish Meteorological Institute
	Assessment of extreme geomagnetic variations is a scientifically interesting challenge and of high societal importance due to space weather impacts on modern infrastructure. We discuss briefly two approches to estimate the magnitude of geomagnetic variations: data-based extrapolations and first-principle simulations. Recent results indicate that the magnetic storms observed within the last 100 years have been clearly smaller than the famous Carrington event in 1859 or the comparable storm in 1921.
10	An evaluation of electric field and network models to account for the frequency dependence of network parameters used in the estimation of geomagnetically induced currents in power systems.	Cilliers, P et al.	Poster
	Pierre Cilliers[1], Robert Weigel[2]
	[1]South African National Space Agency, Hermanus, South Africa; [2]George Mason University, Virginia, USA
	The GICs flowing through neutral connections on high voltage power lines can be related to observed or modelled horizontal geoelectric field components on Earth's surface through the set of “a” and “b” network parameters that represent the geometry and configuration of the networks as well as the network impedances representing the power lines, transformers and capacitors in the network. The use of frequency-dependent network parameters has been demonstrated to give better out-of-sample prediction efficiencies for GICs than the commonly used constant resistive network components. We used a data set comprising 35 days of GIC data sampled at a 1-second cadence in the grounded neutral point of a Y-connected transformer connected to the end of a 187 kV power line at the Memanbetsu substation of the Hokkaido Power Co in Japan, and E-field data recorded at 1-second-cadence at the Memanbetsu Magnetic Observatory, located 9 km from the substation. We will present several approaches for explaining the frequency dependence of network parameters that challenge the implicit assumptions that the E-field is the same everywhere along the power line and that the network is purely resistive at the spectral frequencies of GICs. The proposed approaches could facilitate the interpretation of the anomalies seen in the use of resistive networks, such as the delay between the peak of the electric field and the peak of the observed GIC.
11	Analysis of EGNOS signal in space performances under different types of ionospheric perturbations	Kacem, I et al.	Poster
	Issaad KACEM, Mourad FAKHFAKH, Marzena SPAS, Mohamed OURAINI, Stanislas GUILLEMANT, Lotfi FEJRI and Christopher SANT-ANNA
	European Satellite Services Provider, ESSP
	Space weather and associated disturbances in Earth’s magnetic field can lead to significant ionospheric perturbations. These perturbations are one of the main contributors to Global navigation satellite system (GNSS) positioning errors. In this work, we analyze the impact of three different types of ionospheric perturbations on the European Geostationary Navigation Overlay Service (EGNOS) Signal In Space (SiS) performances. The considered events are polar ionospheric scintillation, equatorial scintillation and Total Electron Content (TEC) increase. In order to identify the major periods of high space weather activity that could have had an impact on the GNSS services in the previous years, we relied on the Kp index and CMEs occurrences over the period 2019 to 2022. One event of each ionospheric perturbation category was selected. For the selected events, we analysed the variations of ionospheric indicators such as the (Vertical Total Electron Content) provided by Universitat Politècnica de Catalunya (UPC) and the Along Arc TEC Rate (AATR) index computed from GNSS observation data extracted from EGNOS Data Access Service (EDAS) ground station network. We also considered other indicators extracted from the data collected by the EGNOS RIMS such as the L2 over L1 signal loss rate. The Grid Ionospheric Vertical Error Indicator (GIVE) over the ECAC region was also considered as intrinsic EGNOS indicator of ionospheric disturbance effects. Finally, the impact of these disturbances on EGNOS Safety of Life (SoL) services availability loss (APV-I and LPV200) was addressed. The northern scintillation caused by geomagnetic storms showed higher impact on EGNOS SIS performances than the equatorial scintillation and then the TEC increase both in amplitude and frequency of occurrence. These results reveal the complex nature of the relationships between ionospheric disturbances and EGNOS SoL services performance.
12	Space Weather nowcast, forecast, archive and alerts products relevant Power System Operators, Pipeline Operators, Resource Exploitation System Operators, and the auroral tourism sector.	Drube, L et al.	Poster
	Line Drube1, Jens Olaf Pepke Pedersen1, Anna Willer1, Nils Olsen1, Jon Thøger2, Norah Kaggwa Kwagala2, and the members of the Geomagnetic Expert Service Center.
	[1] Technical University of Copenhagen, [2] University of Bergen.
	Rapid variations of the geomagnetic field due to space weather can have effects on the ground, such as create geomagnetically induced current in the ground possibly affecting power systems with long high voltage power lines, or create a fluctuating voltage difference between the ground and long pipelines, which can cause fluctuations in the corrosion protection voltage of the pipelines decreasing the effectiveness of that protection. The accuracy of resource exploitation directional drilling can also be affected by variation in the geomagnetic field, and of interest to auroral tourism is when and where the chance of auroral is largest. The ESA Space Weather Service Network offers, among others, several data products relevant for Power System Operators, Pipeline Operators, Resource Exploitation System Operators, and the Auroral Tourism Sector; see more at https://swe.ssa.esa.int/user-domains. These space weather products in the user domain of "Non-Space System Operation (NSO)" cover information on: the present geomagnetic conditions; forecast, data archive and alerts for geomagnetic activity indices; variations of the geomagnetic and electric fields; forecast of geomagnetic storms, information on geomagnetically induced currents, on the pipe-to-soil electric potential, and on the location and visibility of aurora. We present a selection of the NSO-related products provided by the Geomagnetic Conditions Expert Center (G-ESC) of ESA's Space Weather Service Network .
13	INVESTIGATING POSSIBILITY OF GEOMAGNETICALLY INDUCED CURRENTS IN KENYAN ELECTRIC POWER GRID	Omondi, G et al.	Poster
	George Omondi
	Maseno University, Department of Physics and Materials Science, P.O Box 333-40105, Maseno, Kenya
	The Sun emits highly conducting plasma at supersonic speeds of about 500kms-1 into the interplanetary space as a result of the supersonic expansion of the solar corona. These particles cause geomagnetic storms when they interact with the Earth’s magnetic field, leading to the development of an induced potential difference on the surface of the earth called Earth Surface Potential (ESP). The ESP produces Geomagnetically Induced Currents (GICs) in ground-based electrical conductor systems. GICs have been found to cause damage to electrical power transformers, oil and gas pipelines in high latitude regions such as Canada and Finland, mid-latitude regions such as South Africa and low-latitude regions such as Japan. No such studies have been carried out in Kenya although possibility exists that being a low-latitude region, technological systems that rely on electrical power could be affected by GICs. In this study, we calculated the magnitude of GICs during magnetically disturbed days in the year 2009 in Nairobi, Kenya and investigated the correlation of these GICs with observed transformer break downs and power blackouts in the power grid during these times. We used the Magnetic data from the MAGDAS Station and resistivity data from the Departments of Physics and Geology of the University of Nairobi, respectively. The maximum absolute value of modeled GICs was found to be 8 A and this occurred during a minor storm. The results compare well with similar ones obtained in low-latitude regions such as central Japan, where GICs of 45 A have been found. The variation in the geomagnetic field was found to exceed the threshold of 30nT/min. It was found that for each geomagnetic event there was a corresponding power system event either on the same day of the geomagnetic event or later within one week. Nevertheless, our results are model-based and measurements of GICs also need to be carried out in the power grid in Nairobi over a solar cycle if measuring gadgets are installed in order to obtain a more comprehensive account of geomagnetic disturbances on the power system in Nairobi and Kenya at large. From the foregoing, it follows that the power grid in Nairobi, Kenya might have been affected by GICs and so mitigation measures need to be put in place to prevent future power outages and transformer breakdowns arising from the effects of GICs, especially during solar maxima when geomagnetic storms are expected to be more intense. KEY WORDS: Geomagnetically Induced Curren
14	Space weather impact maps for GNSS scintillations	Beeck, S et al.	Poster
	Sarah Beeck[1], Lars Stenseng[2]
	[1]DTU Space, [2]DTU Space
	Precise and reliable positioning is critical infrastructure to ensure safety in the Arctic. Ionospheric scintillation poses a threat to this infrastructure through a possible degradation of GNSS positioning, in worst case to a degree where no GNSS positioning is possible. Therefore, GNSS users in Greenland could greatly benefit from local space weather impact maps. To compute such maps, a relation between the available scintillation indices and the effect on positioning must be established. The quality of the impact maps is determined by how the thresholds of the impact levels are defined. This analysis seeks to identify the optimal threshold values of space weather impact maps for GNSS users in Greenland. It is done by a comparison of cycle slips and phase scintillation data as a method of evaluating the levels of scintillation that lead to cycle slips at different latitudes in Greenland. This is because the number of cycle slips is a more direct measure of the actual impact on the receiver. The thresholds of the impact maps are receiver depend since receivers of varying quality will be affected differently by scintillation. In this study we have chosen to use GNET data for identifying cycle slips, and a collocated network of PolaRx5s receivers for ionospheric scintillation monitoring. This means that the cycle slip detection is based on data from high-quality GNSS receivers. The thresholds found in this study, can therefore also indicate an upper limit of the thresholds for receivers of lower quality. Furthermore, this study gives an indication of whether individual threshold values are optimal for different regions in Greenland. The network of PolaRx5s stations was established in the fall of 2021 and the study is therefore representative of a period with increasing solar activity since we are currently moving towards a solar maximum. Mapping and warnings of GNSS disturbances are thus becoming more relevant and providing integrity information for Arctic GNSS users will become essential in the coming years.