A series of models of the Earth magnetic field and core surface flow are presented. The models were derived sequentially from year 1999 to 2022, using magnetic satellite and ground observatory data. A linear Kalman filter approach and prior statistics based on numerical dynamo runs were used. The core field and secular variation models present the same characteristics as the most recent core field models with slightly higher resolution in time. The core surface flow series of models presents large variations at high latitudes and under the western part of the Pacific Ocean. Filtering out the flow variation periods longer than ∼11.5 years leads to a filtered azimuthal flow with ∼7 years periodicities and patterns propagating westward by ∼60^o longitude per year. These patterns are present mainly at mid- and equatorial latitudes. They are compatible with a perturbation of the main flow made of small columnar flows with rotation axis intersecting the core-mantle boundary between 10^o to 15^o latitudes, and flow speed of less than 5km/y. These columnar flows can be identified at all longitudes, but are particularly strong under the Pacific Ocean or under the Atlantic Ocean from 2005 to 2015.

How to cite: Lesur, V. and Ropp, G.: Core surface flow variations derived from observatory and satellite magnetic data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6576, https://doi.org/10.5194/egusphere-egu23-6576, 2023.

The ESA Swarm mission has, with along- and across-track differences of the magnetic field measurements, made it possible to generate spatial gradients data of the geomagnetic field and its secular variation (SV). Inverting the SV data for core-surface flows allows us to investigate the Earth’s outer core with higher resolution than using vector component data.

We invert for core-surface flow models directly from the spatial gradient tensor SV data, without the use of stochastic or numerical models, imposing flow equatorial symmetry, quasi- or tangential geostrophy, or band-pass filtering. We develop three different types of model, all damped to minimise spatial complexity and minimise acceleration between epochs. The first set is otherwise unconstrained, and different spatial regularisations are used. In the second set, we allow for torsional oscillations by relaxing the temporal damping on certain flow coefficients. The third set has differential damping on the equatorially symmetric and asymmetric flow components, in order to investigate the extent to which asymmetric flow is required to fit the data. We predict the intradecadal variation in length-of-day (LOD) from each model, and find that only the model which allows for torsional oscillations shows a good fit to the LOD data.

The azimuthal acceleration of all three model types shows evidence of fast westward low-latitude waves at the core-surface.  During the 2017 geomagnetic jerk, there is an abrupt westward shift in these wave-features in all our models. Previous literature suggests that geomagnetic jerks may originate from Alfvén wave packets emitted from the inner-outer core boundary, propagating outwards. We suggest that the observed westward shift at the jerk epoch may occur when these wave-packets interfere with the waves at the core surface.

Finally, we consider the use of spatial gradients from the CHAMP mission. Spatial gradients can be derived from along-track differences of the magnetic field from CHAMP, which allows us to compare the quality of core surface flow models from the CHAMP and Swarm missions. Our analysis suggests it is unlikely that CHAMP yields data of sufficient resolution to observe this proposed wave-interaction, showcasing the success of the Swarm mission.

How to cite: Madsen, F. D., Whaler, K., Hammer, M., Holme, R., Brown, W., and Beggan, C.: Investigating geomagnetic jerks with Swarm: Using the spatial gradient tensor for flow modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7679, https://doi.org/10.5194/egusphere-egu23-7679, 2023.

The World Digital Magnetic Anomaly Map is prepared under the auspices of IAGA and the CGMW (Commission for the Geological Map of the World) of UNESCO. A first version was released in 2007 (Korhonen et al., 2007), and a second one in 2015 (Dyment et al., 2015; Lesur et al., 2016) with the mandate to update the version 2.0 using the same methodology when the availability of new data would make it necessary. The present version 2.1, compiled at 5 km interval, at 5 km altitude above the continents and at sea-level over the oceans, includes new datasets: (1) the complete digital aeromagnetic map of Brasil made available by ANP; (2) an improved version of the aeromagnetic map of Russia prepared by V-SEGEI; (3) the second version of the Antarctic Digital Magnetic Anomaly maP (ADMAP; Golynsky et al., 2018) which results from a remarkable international effort during and after the Second International Polar Year; (4) a new map of the Caribbean plate and Gulf of Mexico resulting from the compilation and re-processing of existing marine and aeromagnetic data in the area (Garcia and Dyment, EPSL, 2021, 2022); (5) the updated Magnetic Anomaly Map of Eastern Asia prepared by the CCOP (MAMEA; Ishihara and Uchida, 2021); and (6) a new marine magnetic anomaly data compilation prepared by T. Ishihara and coworkers. The new map will be presented and its improvements over the previous version discussed.

We try to characterize the magnetic signature of the different geological provinces at global scale by comparing WDMAM v.2.1 and the Geological Map of the World (Bouysse et al., 2014, CGMW). The latitudinal and directional dependences of the magnetic anomaly amplitude and shape prevent a direct global comparison. Instead, we examine the distribution of magnetic anomaly amplitudes within the geological provinces continent by continent. We build an histogram of the magnetic anomaly amplitudes for each type of geological province within each studied continent. The histograms resemble normal distributions from which we determine the average amplitude and its standard deviation. The latter reflects how wide is the range of amplitudes in the distribution: a small standard deviation means a narrow distribution and low amplitudes, a large one a wide distribution and high amplitudes. On land, our first investigation suggests that cratons exhibit stronger magnetic anomalies, whereas regions covered by a significant thickness of sediments present weaker anomalies. At sea, large igneous provinces show stronger anomalies, whereas continental platforms and the oceanic crust show similar amplitudes.

How to cite: Dyment, J., Choi, Y., Lesur, V., Garcia Reyes, A., Catalan, M., Ishihara, T., Litvinova, T., and Hamoudi, M.: World Digital Magnetic Anomaly Map (WDMAM) v.2.1 and the magnetic signature of geological provinces, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9725, https://doi.org/10.5194/egusphere-egu23-9725, 2023.

The large-scale electrical conductivity structures in the deep Earth's mantle, in the depth range of 670 to 1400 km, can be in principle determined from Swarm-observed induction response to time-variable magnetospheric currents (Velímský & Knopp 2021). However, these efforts have been so far encumbered by limited spatio-temporal description of the magnetospheric field from moving satellite platforms. In particular, the polar electrojets (PEJs) and field-aligned currents (FACs) are sources of a strong bias in the spherical-harmonic analysis of Swarm magnetic data. An electric circuit model of PEJs and FACs (Martinec & Velímský 2022) provides a novel data processing tool to suppress the bias and obtain a reliable model of the large-scale magnetospheric field during magnetically disturbed times. In this contribution we apply the new magnetospheric field model to the 3-D time-domain  forward and inverse modelling of global electromagnetic induction. We determine its impact on the sensitivity and resolution of the inverse problem, and proceed with regularized 1-D and 3-D inversions to update the electrical conductivity model of the deep mantle. 

How to cite: Velímský, J. and Martinec, Z.: Application of a new magnetospheric field model to 3-D inversion of Swarm magnetic data in terms of mantle electrical conductivity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5013, https://doi.org/10.5194/egusphere-egu23-5013, 2023.

We deal with the analysis of Swarm vector magnetic data to create a circuit model of electric currents flowing in the Earth’s polar ionosphere and the inner magnetosphere. The model is composed of a system of two-dimensional electric currents representing the magnetic fields of three-dimensional ionospheric polar electrojets (PEJs), the field-aligned currents (FACs), magnetospheric ring currents (MRCs) and magnetospherically induced electric currents inside the Earth (MICs) for each Swarm track. We aim to model PEJ and FAC magnetic fields in terms of electric currents on a track-by-track base, subtract those magnetic fields from along-track Swarm magnetic data and estimate the magnetospheric magnetic field (MMF) in discrete time bins. The final model of MMF, named MMC, is represented by the two-circular loop model. Reliability of the approach is demonstrated by the scatter plots of model MMC showing a significantly better agreement with Swarm magnetic field residuals than the existing MMFs. A novelty of the proposed electric circuit model is that it approximately accommodates the known topology of the electric currents flowing in the polar ionosphere and inner magnetosphere at magnetically disturbed times. The proposed method is primarily intended to apply to Swarm signals recorded during magnetic storms.

How to cite: Martinec, Z. and Velímský, J.: An electric circuit model of the Earth's polar electrojets and field-aligned currents for the estimation of magnetospheric magnetic field from along-track Swarm magnetic data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4356, https://doi.org/10.5194/egusphere-egu23-4356, 2023.

Over the past 10 years, the ESA Swarm mission led to many scientific successes sometimes way beyond its primary science targets. One such example is the unanticipated science allowed by the experimental 250 Hz burst mode magnetic scalar data provided by the Absolute Scalar Magnetometers on board the satellites. This burst mode was originally meant to be run briefly for in-orbit calibration and validation activities during the initial months of the Swarm mission. However, and despite the fact that the 250 Hz sampling rate can only access the ELF part of the electromagnetic spectrum, numerous whistler signals could be detected. After carefully assessing the possibility of routinely detecting and characterising such whistlers, it was thus next decided to conduct campaigns of one-week duration every month on Swarm Alpha and Bravo. These started in 2019 and still continue today, the corresponding Burst mode data now being a routine product of the mission.

In this presentation, we will review the main scientific results of these campaigns: geographical and temporal distribution of whistler events as well as the detectability of whistler signals, which we assessed using joint campaigns on the Alpha and Bravo satellites during the recent counter-rotating phase of the Swarm mission. Using ground ionosondes and in-situ electron density measurements we also demonstrated the promising possibility of using whistlers to measure ionosphere plasma density parameters along their path up to the Swarm satellites. Finally, using data from the ground based ELF measurements from WERA, and data from the lightning detection network WWLLN, the originating strikes could also be identified. We found that only the most powerful lightning strikes produce detected whistlers, and that these strikes can sometimes occur several thousands of kilometres away from the satellites.

How to cite: Coïsson, P., Chauvet, L., Hulot, G., Jenner, M., Buresova, D., Truhlik, V., Chum, J., Mlynarczyk, J., Kubisz, J., Léger, J.-M., and Jager, T.: Swarm Absolute Scalar Magnetometer burst mode: from instrument validation to routine observation of intense lightning activity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5167, https://doi.org/10.5194/egusphere-egu23-5167, 2023.

The ESA Swarm mission has been designed to provide high-precision registrations of the Earth's magnetic field. Since its launch, the constellation, consisting of three LEO satellites, measures the magnetic signals coming from Earth's core, mantle, crust, oceans, ionosphere, and magnetosphere. Nearly a decade of Swarm observations, allowed us to expand main goals of the mission and improve our capabilities of detecting magnetic field fluctuations triggered by powerful thunderstorms.

Lightning can generate ultra low frequency fluctuations that leak into the upper ionosphere. This means that some lightning bolts are so powerful that they trigger disturbances in Earth's magnetic field and propagate hundreds of kilometers upwards from the thunderstorm, reaching the altitude of Swarm’s orbit. Thanks to two magnetometers,  the Absolute Scalar Magnetometer ASM and the Vector Fluxgate Magnetometer VFM, Swarm turned into a robust lightning hunter. 

Gathered analysis, utilizing mainly the VFM registrations, show that averaged amplitude of lightning generated fluctuations reaches magnitude of 0.5-1.3 nT (peak-to-peak for the scalar field), while typical time delay between the lightning occurrence and the satellite detection is 0.2-0.5 s and this indicates that Swarm detects rather a direct propagation of lightning-generated disturbance than effects of excitation of the ionospheric Alfvén resonance, which would require a longer time scale.

Since Swarm provides full representations of the magnetic field components, we transform data to the so-called MV frame to extract the maximum amplitude of a given fluctuation regardless of the lightning-satellite mutual orientation and wave polarization. In such a way, Swarm data help to comprehensively characterize  wave properties of detected fluctuations, and this is one of fundamental tasks, especially in the large variety of magnetic field disturbances caused by various types of natural hazard phenomena. 

How to cite: Slominska, E., Strumik, M., and Slominski, J.: A decade of measurements, which turned Swarm into a lightning hunter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14094, https://doi.org/10.5194/egusphere-egu23-14094, 2023.

The ESA Swarm mission was launched in November 2013, and it consists of a constellation of three identical satellites. The main mission objective is to model and analyze the geomagnetic field through the data provided by a vector and a scalar magnetometer on board of each spacecraft (A, B, C).  To fulfill the secondary objectives, the satellites do also carry other instruments, such as an accelerometer expected to measure the non-gravitational forces acting on each satellite. However, the quality of the data retrieved from this instrument was not at the anticipated level and, therefore, the post-processing required to calibrate the signal was significant. Therefore, initially the calibration focused on Swarm C only because it had the best signal-to-noise ratio of the constellation. For this satellite the calibrated accelerometer data are available since the beginning of the mission and they are disseminated bi-monthly. At the end of 2021, the first Swarm A dataset was released and it comprises some months in 2014. Swarm A and C, called the “lower pair”, have flown side-by-side for most of the mission with a separation that spanned from four to ten seconds. Therefore, their measurements are supposed to be nearly identical after calibration.

A recent publication, which is discussed in this talk, demonstrated that a comparison between Swarm A and Swarm C calibrated accelerometer dataset shows the expected correlation. After applying a high-pass filter to both satellites’ dataset, very similar features are visible at the equator and at the poles. The “long time scale” events at the equator show a correlation between the equatorial mass anomaly and the equatorial ionization anomaly. At the poles, the “short time scale” events can be related to the Polar Cap index and to the field-aligned currents, which are measured on board by the Swarm magnetometers. Furthermore, these features agree with previous literature based on CHAMP and GRACE data.

For the first time the Swarm accelerometer data deliver scientific results, in particular in the field of thermosphere and ionosphere coupling.

How to cite: Iorfida, E., Daras, I., and Strømme, A.: Swarm A and C Accelerometer - data analysis and scientific outcome, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7872, https://doi.org/10.5194/egusphere-egu23-7872, 2023.

So-called platform magnetometers, mounted on a variety of non-dedicated satellites in Low-Earth orbit, are promising instruments to increase the spatiotemporal coverage of space-based measurements of the Earth’s magnetic field. However, these instruments often need to be calibrated to ensure a scientific accuracy and usability of the data they collect. To do this, it is important to gather information about the satellite to correct artificial disturbances caused by other payload systems as well as other influencing properties. In the past, we demonstrated that a Machine Learning-based calibration achieves competitive results. By using machine learning techniques, the magnetometer signal can be adapted to account for artificial disturbances and the proposed non-linear regression method can automatically identify relevant features and their crosstalk, enabling the use of a wider range of inputs. This reduces the analytical work required for the calibration of platform magnetometers, resulting in faster, more precise, and easily accessible magnetic datasets from non-dedicated missions. The calibrated datasets are made publicly available.

In this work, we propose an extension for the known approach by incorporating the physical Biot-Savart formula into a neural network, which results in a physics-informed neural network. This improves the modeling and correction of the impact of current-induced artificial magnetic fields on the satellite and its magnetic measurements. In addition, the Average Magnetic field and Polar current System (AMPS) model is combined with the CHAOS-7 model, improving the reference model of the calibration, especially for the polar regions. This extended approach is applied to the GOCE and GRACE-FO satellite missions and their respective measurements. In the future, the underlying software shall be published and applied to a wider variety of satellites to improve the accuracy of their platform magnetometer measurements. By making this tool publicly available, we hope to enable other satellite operators to calibrate their instruments, improve the quality of their data, and make additional data available to the scientific community.

How to cite: Styp-Rekowski, K., Michaelis, I., Korte, M., Stolle, C., and Kao, O.: Improving Platform Magnetometer Measurements Using Physics-informed Neural Networks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8273, https://doi.org/10.5194/egusphere-egu23-8273, 2023.

The Enhanced Polar Outflow Probe (e-POP) was launched as part of the Canadian CASSIOPE small satellite into an elliptic polar orbit in September 2013. It then joined the ESA Swarm mision under ESA's Third Party Mission Programme in 2018, as a Fourth Element of the Swarm constellation of satellites, to take advantage of the highly complementary and synergistic instrumentation and orbital coverage between CASSIOPE/e-POP and the three Swarm satellites. This scientific synergy has made possible a new, high-resolution multipoint data set of magnetic field, GPS, and related optical, radio wave, and plasma composition observations, as an addition to the Swarm mission data system and the basis for a number of new scientific investigations. We will review examples of 'scientific success stories' from such investigations. We will also present examples of new investigations in the next chapter of Swarm Echo: these investigations were not planned previously but have become feasible after the recent partial failure of the spacecraft attitude control system, which necessitated a change to a new spacecraft attitude configuration that will serendipitously provide the necessary observing geometry for such innovative investigations

How to cite: Yau, A. and Howarth, A.: CASSIOPE - Swarm Echo as a Fourth Element of the Swarm Constellation: Scientific Synergies and the Next Chapter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2172, https://doi.org/10.5194/egusphere-egu23-2172, 2023.

We have performed a statistical analysis of small-scale (sub-decameter) plasma density irregularities in the topside ionosphere (at 325-1500 km altitude) using the high-cadence (1000 samples/sec) sensor surface current data from the Imaging Rapid-scan Ion Mass Spectrometer (IRM) onboard the Swarm-E / Enhanced Polar Outflow Probe (e-POP). The measured current consists of contributions from the ambient and non-ambient electrons and ions, and it is proportional to and serves as a proxy for the local plasma density. The high-cadence current data are averaged over time intervals up to 0.5 s (to facilitate comparison with previous studies) and the analysis is undertaken separately for the case of positive and negative net currents, respectively. We have developed and validated an algorithm to identify small-scale structures of plasma density depletions and enhancements, by finding local minima (depletions) and maxima (enhancements) in the measured current amplitude in each case.  We will compare and contrast the statistical distributions of small-scale plasma density depletion and enhancement structures down to sub-100 m scale, including their altitude, magnetic latitude, magnetic local time distributions and spectral characteristics.

How to cite: Kastyak-Ibrahim, M., Howarth, A., White, A., and Yau, A.: Small-Scale (Sub-decameter) Plasma Density Irregularities in the Topside Ionosphere Using High-cadence Plasma Current Measurements on e-POP (Swarm-E), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3667, https://doi.org/10.5194/egusphere-egu23-3667, 2023.

Swarm-E carries the e-POP payload, which consists of eight scientific instruments. The Radio Receiver Instrument (RRI) on e-POP may be used to detect density structures that modify the characteristics of transionospheric HF radio waves from ground-based transmitters. RRI has a cross-dipole antenna designed to determine the polarisation characteristics of the incident radio waves. Joint experiments with other instruments, IRM (Imaging and Rapid-scanning ion Mass spectrometer) and MGF (Fluxgate Magnetometer), complement RRI for better understanding of the local ionosphere conditions and integrated conditions along the path between a ground-based transmitter and Swarm-E. Under optimum conditions, the RRI determines the full polarisation characteristics. This presentation discusses past and future contributions to ionospheric science of the Swarm constellation.

How to cite: Kalafatoglu Eyiguler, E. C., Danskin, D. W., Pandey, K., Hussey, G. C., Gillies, R. G., and Yau, A. W.: Understanding Ionospheric Conditions using the e-POP on Swarm-E, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9101, https://doi.org/10.5194/egusphere-egu23-9101, 2023.

The project “Characterization of Ionospheric TurbulENce Level by Swarm Constellation (INTENS)”, which was completed in 2021, was a collaboration between two Italian research institutes (INGV and INAF) and the National Observatory of Athens (NOA). It was funded by the European Space and was devoted to the investigation of turbulence and complexity in the ionospheric F2 region using data coming from the Swarm constellation. The obtained results were very intriguing because they provided the first global-scale characterization of the scaling properties of electron density and magnetic field fluctuations at the Swarm altitude as a function of geomagnetic activity and orientations of interplanetary magnetic fields. They also provided the opportunity to quantify changes in the complexity of the magnetosphere-ionosphere coupling system and to comprehend how it reacts to the onset and evolution of intense magnetic storms using entropy measures.

Despite the fact that the INTENS project is no longer active, research continues. The aim of this presentation is to summarize some recent results and to show how turbulence can be one of the most significant processes for the generation of plasma density irregularities which strongly affect the Global Navigation Satellite System. A thorough understanding of turbulent ionospheric fluctuations can be crucial in the future creation of GPS Loss of Lock hazard maps, greatly advancing the effort to minimize the effects of space weather. Any future satellite mission that can accurately measure the magnetic field and electron density at high frequency, as the NanoMagSat mission should be able to, will be necessary to extend the reliability of the results to ever smaller spatio-temporal scales.

How to cite: De Michelis, P.: The project “Characterization of Ionospheric Turbulence Level by Swarm Constellation”: Results and Prospects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11583, https://doi.org/10.5194/egusphere-egu23-11583, 2023.

Electron density (N_e) and electron temperature (T_e) observations collected by Langmuir Probes (LPs) on board the European Space Agency’s Swarm satellites are used to characterise the N_e−T_e correlation in the topside ionosphere. The large dataset of Swarm LPs in-situ observations at 2-Hz rate, covering the years 2014−2021, allowed us to investigate the correlation properties of the topside ionospheric plasma for different diurnal and seasonal conditions, with a coverage and a detail never reached before. Spearman correlation coefficients (R_Spearman) are calculated on joint probability distributions between N_e and T_e for specific conditions. Results are given as maps of R_Spearman as a function of the Quasi-Dipole (QD) magnetic latitude and magnetic local time (MLT) coordinates, for different seasons. This study highlights, for the first time, the N_e−T_e correlation at high latitudes, and provides a global description of the corresponding diurnal trend for different seasons. A negative correlation is found at the equatorial morning overshoot, during daytime at mid latitudes, and during night-time at subauroral latitudes (ionospheric trough). Conversely, a positive correlation dominates the night-time sector at mid and low latitudes, and to a minor extent the low latitudes from 09:00 MLT onwards. A seasonal dependence of the correlation is visible only at very high latitudes where the general pattern of anti-correlation is broken around ±75° QD latitude in the summer season.

How to cite: Pignalberi, A., Giannattasio, F., Pezzopane, M., Coco, I., and Alberti, T.: On the correlation between electron density and temperature in the topside ionosphere through Swarm satellites data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5696, https://doi.org/10.5194/egusphere-egu23-5696, 2023.

How to cite: Lovati, G., De Michelis, P., Consolini, G., Pezzopane, M., Pignalberi, A., and Berrilli, F.: The relation between GPS loss of locks and the Interplanetary Magnetic Field orientation: Swarm observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5123, https://doi.org/10.5194/egusphere-egu23-5123, 2023.

The Swarm data products are well-suited to address a number of crucial topics for space weather science and monitoring, such as investigating spatial and temporal characteristics of ionospheric irregularities or improving topside approaches in ionospheric models for monitoring and forecasting the dynamics of the geo-plasma environment. Precision and safety of life applications using trans-ionospheric signals require key information on space weather conditions in particular on the perturbation degree of the ionosphere. Such applications are particularly vulnerable against severe spatial gradients and rapid changes of the electron density (Ne) as well as the total electron content (TEC) measured along different satellite‐receiver links. Here, we propose two new Swarm products 1) the TEC Gradient Ionosphere indeX (TEGIX) and 2) the Ne Gradient Ionosphere indeX (NEGIX). The TEGIX estimates spatial TEC gradients in the topside ionosphere (Swarm up to GNSS orbit) using GNSS Precise Orbit Determination (POD) measurements whereas the NEGIX estimates spatial Ne gradients using Swarm onboard Langmuir probe (LP) measurements (2 Hz sampled).  The approach takes benefit from the coordinated flight of satellites A and C at an orbit height of about 460 km. We will present a first version of both products and will explore their potential impact, utility, and use through case studies.

Acknowledgement:

The work is funded by the MIGRAS (Monitoring of Ionospheric Gradients At SWARM) project under the Swarm DISC Subcontract Doc. no: SW‐CO‐DTU‐GS‐133, Rev: 1.

How to cite: Hoque, M. M., Jakowski, N., Cahuasqui Llerena, J. A., Buchert, S. C., Kriegel, M., David, P., Vasylyev, D., Berdermann, J., and Nielsen, K.: Monitoring ionospheric gradients using SWARM satellite data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6558, https://doi.org/10.5194/egusphere-egu23-6558, 2023.

European and North American near-noontime ionosonde observations along with CHAMP and Swarm neutral density measurements were used during a major Arctic SSW in January  2009 and a minor Antarctic SSW in September 2019 to retrieve variations of thermospheric parameters (neutral composition, temperature, winds) related to these SSW events. Neutral density observations were used in the retrieval process as a fitted parameter. The main effect of SSW 2009 event is a strong decrease of the atomic oxygen [O] abundance in the thermosphere which is confirmed by satellite neutral gas density observations. Along with this no thermosphere cooling effects were revealed.

The duration of [O] decrease related to SSW is around 3-5 days in the vicinity of the SSW peak. The decrease of [O] depends on the intensity of SSW. The minor Antarctic SSW event in September 2019 manifested no pronounced thermospheric effects in the Northern Hemisphere.

How to cite: Perrone, L. and Mikhailov, A.: The thermospheric effects of SSWs observed in 2009 and 2019 at mid latitudes of the Northern Hemisphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1889, https://doi.org/10.5194/egusphere-egu23-1889, 2023.

SwarmPAL is a new Python package under development with support from Swarm DISC (Data, Innovation, and Science Cluster). This project aims to provide the research community with a suite of tools to rapidly access, analyse, and visualise data from Swarm (and related data sources). By relying on the VirES system [1] for data access and other utilties, this greatly reduces the complexity required within SwarmPAL. By making use of HAPI [2], we can also connect to many other data sources to retrieve data from beyond Swarm. This is part of an overall strategy for integrating with the wider Python (and Jupyter) ecosystem, while being cognisant of the particular scientific landscape occupied by Swarm [3].

SwarmPAL is developed by researchers and research software engineers: this ensures a close fit between the development process and the needs of researchers, as well as fostering software skills within the research community. Through several other DISC activities we bring different research teams together, working on different areas of Swarm science, to collaboratively work on the SwarmPAL system. Namely, these activities currently include the TFA (time frequency analysis), and DSECS (dipolar spherical elementary current systems) toolboxes. These toolboxes provide tools to rapidly and configurably apply analyses to Swarm data, while the SwarmPAL package provides the home for these, together with all the maintenance and documentation that this implies. The development process is made with a strong focus on sustainability and open source [4].

[1] https://vires.services
[2] https://hapi-server.org
[3] https://doi.org/10.3389/fspas.2022.1002697
[4] https://github.com/Swarm-DISC/SwarmPAL

How to cite: Smith, A., Papadimitriou, C., Balasis, G., Käki, S., Hoppe, T., and Vanhamäki, H.: Developing the SwarmPAL Python package, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10157, https://doi.org/10.5194/egusphere-egu23-10157, 2023.

The Swarm mission concept is innovative in its recognition that high-quality measurements of the geomagnetic field from LEO require accurate knowledge of Earth’s plasma environment, and furthermore that combined, precision measurements of fields, plasmas and neutral density from polar orbit provide a new window into ionosphere-thermosphere-magnetosphere (ITM) coupling and science. During the first decade of operations, event-based studies have led to new discoveries such as extreme plasma flows associated with the Birkeland current systems, the electrodynamic structure of multiple auroral arcs, the sub-auroral “STEVE” phenomenon, and the existence of standing Alfvén waves at equatorial latitudes. At the same time, the mission has accumulated an extensive database of measurements at high spatial resolution collected over a wide range of condition covering nearly a full solar cycle; these data have been used in longer-term statistical studies of plasma properties, high-latitude convection and ITM coupling via Poynting flux. As we enter the next decade of operations, the Swarm data are increasingly being used to inform empirical and physics-based models of the ionosphere; these in turn will comprise an important part of the long-term legacy of the Swarm mission. This talk will highlight scientific discoveries from the first decade of EFI operations, centred on observations of ion flows and associated electric fields from the EFI’s Thermal Ion Imagers, and made possible by a large and active community of collaborators. 

How to cite: Knudsen, D. and Burchill, J.: Swarm Electric Field Instruments' Thermal Ion Imagers: A Decade of Discovery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5288, https://doi.org/10.5194/egusphere-egu23-5288, 2023.

We review a number of studies, undertaken during the 10 years of Swarm, using distributed, multi-scale measurements arising from the combination with Cluster, MMS and ground based arrays. The scaling, coherence and correlation of field-aligned current sheets (FACs) connecting different regions of the magnetosphere have been explored with associated analysis techniques using these multi-point measurements at both low (LEO) and high altitudes, and in relation to (R1/R2) auroral boundaries. Individual events can map to conjugate current density distributions at the magnetopause and ring current and regions in between; as well as to associated  ground signatures, driven by the external conditions. Large and small-scale (MLT) trends in FAC orientation can be inferred from dual-spacecraft (e.g. the Swarm A&C spacecraft). Conjugate effects seen in ground (dH/dt), ionospheric and magnetospheric magnetic signals show that intense, coherent FA currents can take place in the polar cusp during the main phase of a geomagnetic storm and at near tail local times during substorm activity, at different altitudes. In the former event the mesoscale FACs show vertical scaling and a corresponding geomagnetic disturbance, driven by unsteady magnetic reconnection at the magnetopause. In the latter event, the most intense dH/dt is shown to be associated with FACs driven into the ionosphere by the arrival of bursty bulk flows BBFs at geosynchronous orbit (linked via a modified sub-storm current wedge, SCW). In situ ring current morphology can also be investigated by MMS, THEMIS and Cluster during the Swarm era, and can be compared to distributions of R2-FACs.

How to cite: Dunlop, M., Dong, X., Tan, X., Yang, J., Wei, D., and Xiong, C.: Review of coordinated measurements with Swarm and Cluster : multi-scale magnetospheric and ground currents, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3621, https://doi.org/10.5194/egusphere-egu23-3621, 2023.

The three spacecraft which constitute the Swarm mission are equipped with the Micro Advanced Stellar Compass (μASC) provided by the Technical University of Denmark (DTU) for attitude determination. Each μASC is comprised of three Camera Head Units (CHUs) for a total of nine cameras on the mission. The CCD sensor inside the CHUs are sensitive to energetic particle irradiation which appear as transient bright pixels dubbed ’Energetic Particle Detections’ (EPDs) on the star field images.

For more than five years the μASCs on-board Swarm have transmitted the occurrence of EPDs to ground and thereby effectively added high energy radiation monitoring capabilities to the Swarm mission. The high sensitivity, high sample rate (1-2 Hz), orientation of the camera heads, simultaneous measurements from all three spacecraft and near-polar orbits at an altitude of 450-510 km and allows for continuous and real-time monitoring of the high energy (>65 MeV) proton environment in LEO. This data uncover short and long term changes in particle flux in e.g. the South Atlantic Anomaly (SAA) of relevance for future mission planning.

The same radiation monitoring capability exists on NASA’s Magnetospheric Multiscale Mission (MMS) which, due to its highly elliptical orbit, survey the Van Allen radiation belts and detect enhanced radiation levels in the belts associated with geomagnetic storms. Combining data from the μASCs onboard Swarm and MMS provides unique insight into the injection mechanisms and dynamics of very high energy particles which is currently poorly understood. This work presents observations and results using high energy radiation data obtained from the μASC on board ESA’s Swarm mission, from February 2018 to February 2023, in combination with μASC data from MMS.

How to cite: Toldbo, C., Herceg, M., Sushkova, J., Denver, T., Henneke, J., Benn, M., Jørgensen, P. S., Merayo, J. M. G., Qamili, E., Hoyos Ortega, B., Haagmans, R., Vogel, P., Strømme, A., Shulman, S., and Jørgensen, J. L.: The High Energy Particle Populations of Earth Mapped by Swarm and MMS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12663, https://doi.org/10.5194/egusphere-egu23-12663, 2023.

In this work, a new method to define a background for the topside ionospheric electron density from satellite in-situ measurements is proposed as a useful tool for analysis of plasma density variations at LEO satellites heights. The method is applied to the data acquired by the Langmuir Probes onboard CHAMP satellite during the years 2004 and 2009, and the three Swarm satellites during 2016 and 2017 in the 15°-wide mid-latitudinal belt from 35°N to 50°N, and any longitude. CHAMP/Swarm in-situ measurements have also been used to check and compare such a new defined background with the one computed directly from IRI-2016 electron density output at satellite altitude. A general overestimation of the electron density from IRI during noon hours is highlighted, despite an underestimation of IRI with respect to Swarm-derived background for Swarm 2017 data is found as well, while the two backgrounds result more in agreement during night-time. Finally, the analysis of 2004 plasma data suggests that the IRI-2016 model could be used as a background during periods characterized by high levels of geomagnetic activity under high solar activity conditions.

How to cite: Sabbagh, D., Ippolito, A., Marchetti, D., Perrone, L., De Santis, A., Campuzano, S. A., Cianchini, G., and Piscini, A.: Ionospheric mid-latitude electron density background definition from CHAMP and Swarm satellite measurements under different solar conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6437, https://doi.org/10.5194/egusphere-egu23-6437, 2023.

The 16 Hz plasma density measurements provided by the high-resolution faceplate onboard Swarm satellites can be utilized to reconstruct the one-dimensional spectral slope (p) of the power spectrum of the plasma density irregularity. The 16 Hz sampling rate at Swarm orbital features (speed of ~7.5 km/s on quasi-polar orbits) allows modelling spatial scales of about 500 m along the flight trajectory, which are slightly above the first Fresnel zone, the upper limit of the scale sizes of the irregularities causing scintillation on Global Navigation Satellite Systems (GNSS) signals. 

The p-value is a key parameter in estimating the scintillation strength and thus a Swarm ionospheric scintillation (SWIS) proxy is investigated. Such approach, once consolidated, will benefit the scientific community in studying, monitoring and modelling the small-scale irregularities; specially in contexts where ground based GNSS scintillation monitoring is not available, for example over the oceans.

In this work, p-value from Swarm, combined with the reconstruction of the irregularity layer , are ingested to compute the amplitude scintillation index (S4) using Rino’s theory of weak scattering. In this work, the model formulation and sample results of S4 estimation from Swarm are demonstrated. Results of validating SWIS S4 against S4 from ground based GNSS scintillation for selected key ionospheric sectors are also shown. The results demonstrate that the model can capture the amplitude scintillation index inflation both at low and high latitudes, demonstrating the capability of detecting the equatorial and the (rare) polar amplitude scintillation from Swarm measurements. 

How to cite: Imam, R., Spogli, L., Alfonsi, L., Cesaroni, C., Jin, Y., Clausen, L., Wood, A., and Miloch, W.: Determining the L-band amplitude scintillation index from Swarm faceplate plasma measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7914, https://doi.org/10.5194/egusphere-egu23-7914, 2023.

How to cite: Gomez Perez, N. and Beggan, C.: A Swarm-only night-side magnetospheric model to degree and order 3, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14565, https://doi.org/10.5194/egusphere-egu23-14565, 2023.

The almost one decade of operation of ESAs Swarm mission provides an unprecedented opportunity to investigate the appearance of small-scale nonlinear magnetic field irregularities in the topside ionosphere in terms of various climatological and solar-cycle conditions. Within the framework of the EPHEMERIS project supported by ESA we have developed an index for the characterization of the intermittent status of the compressional and tangential (i.e., parallel and perpendicular to the mean background field, respectively) magnetic field fluctuations along the orbits of the Swarm spacecraft triplet. The index is called intermittency index, in short IMI. IMIs are computed for consecutive overlapping segments of Swarm’s magnetic field records by evaluating the deviation of their statistical distribution from the Gaussian distribution. By portraying the global spatial distribution of IMIs, it turns out that the most intensive intermittent fluctuations appear in the polar and equatorial regions, due to auroral field-aligned currents (FAC) and equatorial spread F and plasma bubble phenomena, respectively. Making use of the Adjusted Spherical Cap Harmonic (ASHA) expansion of IMIs, we model the distribution of the intermittent transverse magnetic fluctuations in the polar region in terms of geomagnetic latitude and magnetic local time (MLT), for different geomagnetic activities. We show that the most intermittent fluctuations at high latitudes are distributed about two oval regions that adjoin in the night sector. The ovals expand towards the equator with increasing geomagnetic activity. We argue that the boundaries of the poleward oval coincide with the locations of FACs, while the equatorward oval of intermittent fluctuations (separating from the poleward oval in the noon sector) corresponds to the ionosphere footprint of the plasmasphere boundary, i.e. the plasmapause. These findings are reinforced by independent aurora oval and plasmapause models.

How to cite: Kovacs, P., Heilig, B., Bebesi, Z., and Opitz, A.: Modelling the distribution of intermittent magnetic field fluctuations recorded by the Swarm mission in the polar area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15810, https://doi.org/10.5194/egusphere-egu23-15810, 2023.

The equatorial ionization anomaly (EIA) is one of the most important phenomena at equatorial and low latitudes, which is caused by the daytime eastward electric field via E×B effect. The well-developed EIA at dayside is thought to be a quite large structure with two crests extending to ±15° magnetic latitude, and the plasma density distributes quite smooth along the magnetic fluxtube. However, an additional density peak at poleward of the EIA crests is sometimes observed from the high-resolution plasma density measurements of Swarm. The additional peak is observed at the poleward of EIA crest only in the summer hemisphere, and shows a local time preference between 09:00 and 24:00. From a global view, the additional peak has relatively large occurrence at the norther hemisphere in the pacific longitudes. From the perspective of constellation, the Swarm B can revisit the same longitude of Swarm A/C, though with a certain time day. The delay time gradually increases from a few minutes to a few hours. By comparing the location of the additional peak observed by Swarm B and Swarm A/C, we found the peak keeps at a rather constant latitude irrespective of the delay time between Swarm satellites. Possible drivers for causing such additional peak have been further discussed.

How to cite: Xiong, C. and Huang, Y.: An additional plasma density peak at poleward of the equatorial ionization anomaly crests observed by Swarm, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4333, https://doi.org/10.5194/egusphere-egu23-4333, 2023.

In October 2022 an audio installation using Data Sonification methods premiered in Copenhagen. The project was a sonic representation of Earth’s magnetic field played on a 32-channel speaker system dug into the ground of a public square. The project was a massive success – particularly online with close to a million plays on ESA’s SoundCloud and thus proved a great opportunity to showcase the important work in Earth Observation done within the Swarm community.

The audio installation is an artistic representation controlled by magnetic field data through a sonification method called parameter mapping. The output of the 32 speakers was controlled individually by fluctuations in the magnetic field strength at 32 locations on the globe. Data was taken from the GGF100k – a global field model going back 100.000 years – and condensed into a 5-minute sequence composed of 32 different tracks running simultaneously. Six different parameters were mapped to various qualities of the audio playback (volume, pitch, filter, sample playback speed); these included the three components of the magnetic field at the core mantle boundary, the rate of change, and the field average at surface level.

The soundtrack was meant to give the listener an impression of a living planet in constant flux and is build up from recordings of natural sounds in various combinations. This presentation will describe the approach and give a demonstration of the results. In addition, it will briefly discuss data sonification as a method for inclusion and science outreach.

How to cite: Nielsen, K., Linden-Vørnle, N., Kloss, C., and Finlay, C.: Eerie sounds of Earth’s magnetic field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6799, https://doi.org/10.5194/egusphere-egu23-6799, 2023.