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Data used in support of the journal article of the name "The loss of the Starlink satellites in February 2022: How moderate geomagnetic storms can adversely affect assets in Low-Earth orbits", including: 1. Average values of J^2, J_parallel^2 within the magnetosphere from the CESSI-STORMI module as a function of time. 2.Average values of J^2, J_parallel^2 within the magnetospherefrom SWMF/BATSRUS as a function of time. 3. Total Joule heating of the atmosphere obtained from SWMF/BATSRUS as a function of time. Values for J^2 andJ_parallel^2 are given up to six decimal places. &nbsp

This perspective article discusses the knowledge gaps and open questions regarding the solar and interplanetary drivers of space weather conditions experienced at Mars during active and quiescent solar periods, and the need for continuous, routine observations to address them. For both advancing science and as part of the strategic planning for human exploration at Mars by the late 2030s, now is the time to consider a network of upstream space weather monitors at Mars. Our main recommendations for the heliophysics community are the following: 1. Support the advancement for understanding heliophysics and space weather science at ∼1.5 AU and continue the support of planetary science payloads and missions that provide such measurements. 2. Prioritize an upstream Mars L1 monitor and/or areostationary orbiters for providing dedicated, continuous observations of solar activity and interplanetary conditions at ∼1.5 AU. 3. Establish new or support existing 1) joint efforts between federal agencies and their divisions and 2) international collaborations to carry out #1 and #2.

The propagation of coronal mass ejections (CMEs) through the solar corona and interplanetary space is one of the major topics of heliophysics research. Far from being static, solid structures, CMEs travel away from the Sun through a structured ambient solar wind and interplanetary magnetic field that can lead to varied evolutionary outcomes, including deflections, rotations, deformations, and erosion. The complexity of the myriad processes dictating CME evolution in interplanetary space make it clear that determining the global configuration of a CME from single-spacecraft measurements—representing a 1D trajectory through a large 3D structure—is a particularly arduous task. For this reason, the community has taken advantage of fortuitous spacecraft alignments in the inner heliosphere to perform multi-probe analyses of CMEs, with the aim to obtain a deeper insight into their internal magnetic field and plasma properties, as well as their interactions with the ambient solar wind.In this presentation, we will first provide a brief review of the current status of research and understanding of the propagation of CMEs in the inner heliosphere, in particular from a multi-spacecraft perspective. We will then show a few recent examples of CME events that were observed in situ by two or more probes, highlighting the importance of considering the whole heliospheric context when analysing and interpreting measurements that are taken over more or less large spatial scales. Finally, we will conclude by addressing the need for dedicated multi-spacecraft missions for CME science realised e.g. via satellite constellations, which have been gaining increasing interest over recent years., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Diversity, equity and inclusion (DEI) programs can only be implemented successfully if proper work-life balance is possible in Heliophysics (and in STEM field in general). One of the core issues stems from the culture of "work-above-life" associated with mission concepts, development, and implementation but also the expectations that seem to originate from numerous announcements from NASA (and other agencies). The benefits of work-life balance are well documented; however, the entire system surrounding research in Heliophysics hinders or discourages proper work-life balance. For example, there does not seem to be attention paid by NASA Headquarters (HQ) on the timing of their announcements regarding how it will be perceived by researchers, and how the timing may promote a culture where work trumps personal life. The same is true for remarks by NASA HQ program officers during panels or informal discussions, where seemingly innocuous comments may give a perception that work is expected after "normal" work hours. In addition, we are calling for work-life balance plans and implementation to be one of the criteria used for down-selection and confirmation of missions (Key Decision Points: KDP-B, KDP-C)., Comment: White paper submitted to the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033; 6 pages

We present simulation results of a gradual solar energetic particle (SEP) event detected on 2021 October 9 by multiple spacecraft, including BepiColombo (Bepi) and near-Earth spacecraft such as the Advanced Composition Explorer (ACE). A peculiarity of this event is that the presence of a high speed stream (HSS) affected the low-energy ion component ($\lesssim 5$ MeV) of the gradual SEP event at both Bepi and ACE, despite the HSS having only a modest solar wind speed increase. Using the EUHFORIA (European Heliospheric FORecasting Information Asset) magnetohydrodynamic model, we replicate the solar wind during the event and the coronal mass ejection (CME) that generated it. We then combine these results with the energetic particle transport model PARADISE (PArticle Radiation Asset Directed at Interplanetary Space Exploration). We find that the structure of the CME-driven shock was affected by the non-uniform solar wind, especially near the HSS, resulting in a shock wavefront with strong variations in its properties such as its compression ratio and obliquity. By scaling the emission of energetic particles from the shock to the solar wind compression at the shock, an excellent match between the PARADISE simulation and in-situ measurements of $\lesssim 5$ MeV ions is obtained. Our modelling shows that the intricate intensity variations observed at both ACE and Bepi were influenced by the non-uniform emission of energetic particles from the deformed shock wave and demonstrates the influence of even modest background solar wind structures on the development of SEP events., Comment: 13 pages, 7 figures, accepted for publication in The Astrophysical Journal

Streamer-blowout coronal mass ejections (SBO-CMEs) are the dominant CME population during solar minimum. Although they are typically slow and lack clear low-coronal signatures, they can cause geomagnetic storms. With the aid of extrapolated coronal fields and remote observations of the off-limb low corona, we study the initiation of an SBO-CME preceded by consecutive CME eruptions consistent with a multi-stage sympathetic breakout scenario. From inner-heliospheric Parker Solar Probe (PSP) observations, it is evident that the SBO-CME is interacting with the heliospheric magnetic field and plasma sheet structures draped about the CME flux rope. We estimate that $18 \, \pm \, 11\%$ of the CME's azimuthal magnetic flux has been eroded through magnetic reconnection and that this erosion began after a heliospheric distance of ${\sim}0.35$ AU from the Sun was reached. This observational study has important implications for understanding the initiation of SBO-CMEs and their interaction with the heliospheric surroundings., 21 pages, 6 figures, 3 videos

We investigate the effects of the evolutionary processes in the internal magnetic structure of two interplanetary coronal mass ejections (ICMEs) detected in situ between 2020 November 29 and December 1 by Parker Solar Probe (PSP). The sources of the ICMEs were observed remotely at the Sun in EUV and subsequently tracked to their coronal counterparts in white light. This period is of particular interest to the community since it has been identified as the first widespread solar energetic particle event of Solar Cycle 25. The distribution of various solar and heliospheric-dedicated spacecraft throughout the inner heliosphere during PSP observations of these large-scale magnetic structures enables a comprehensive analysis of the internal evolution and topology of such structures. By assembling different models and techniques, we identify the signatures of interaction between the two consecutive ICMEs and the implications for their internal structure. We use multispacecraft observations in combination with a remote-sensing forward modeling technique, numerical propagation models, and in-situ reconstruction techniques. The outcome, from the full reconciliations, demonstrates that the two CMEs are interacting in the vicinity of PSP. Thus, we identify the in-situ observations based on the physical processes that are associated with the interaction and collision of both CMEs. We also expand the flux rope modeling and in-situ reconstruction technique to incorporate the aging and expansion effects in a distorted internal magnetic structure and explore the implications of both effects in the magnetic configuration of the ICMEs.

Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and magnetic fields from the Sun. They are considered to be the main drivers of strong space weather events at Earth and their arrival time and associated shocks are one of the key aspects of space weather. Multiple models have been developed over the past decades to be able to predict the propagation of CMEs in the interplanetary space and their arrival time at Earth. Such models require input from observations, which can be used to fit the CME to an appropriate structure. The forecasting of CME arrival has proven to be exceedingly challenging. One of the major setbacks is the uncertainty of the CME observational input. When determining input parameters for CME propagation models, it is common procedure to derive kinematic parameters from remote-sensing data. The resulting parameters can be used as inputs for the CME propagation models to obtain an arrival prediction time of the CME f.e. at Earth. However, when fitting the CME structure to obtain the needed parameters for simulations, different geometric structures and also different parts of the CME structure can be fitted. These aspects, together with the fact that 3D reconstructions strongly depend on the subjectivity and judgement of the scientist performing them, may lead to uncertainties in the fitted parameters. Up to now, no large study has tried to map these uncertainties and to evaluate how they affect the modelling of CMEs. We will discuss these limits in the scope of the CME input analysis that is performed by the ISSI Bern team on "Understanding Our Capabilities In Observing and Modelling Coronal Mass Ejections".

Current efforts in space weather forecasting of CMEs have been focused on predicting their arrival time and magnetic structure. To make these predictions, methods have been developed to derive the true CME speed, size, position, and mass, among others. Difficulties in determining the input parameters for CME forecasting models arise from the lack of direct measurements of the coronal magnetic fields and uncertainties in estimating the CME 3D geometric and kinematic parameters after eruption. White-light coronagraph images are usually employed by a variety of CME reconstruction techniques that assume more or less complex geometries. This is the first study from our International Space Science Institute (ISSI) team “Understanding Our Capabilities in Observing and Modeling Coronal Mass Ejections”, in which we explore how subjectivity affects the 3D CME parameters that are obtained from the Graduated Cylindrical Shell (GCS) reconstruction technique, which is widely used in CME research. To be able to quantify such uncertainties, the “true” values that are being fitted should be known, which are impossible to derive from observational data. We have designed two different synthetic scenarios where the “true” geometric parameters are known in order to quantify such uncertainties for the first time. We explore this by using two sets of synthetic data: 1) Using the ray-tracing option from the GCS model software itself, and 2) Using 3D magnetohydrodynamic (MHD) simulation data from the Magnetohydrodynamic Algorithm outside a Sphere code. Our experiment includes different viewing configurations using single and multiple viewpoints. CME reconstructions using a single viewpoint had the largest errors and error ranges overall for both synthetic GCS and simulated MHD white-light data. As the number of viewpoints increased from one to two, the errors decreased by approximately 4 in latitude, 22 in longitude, 14 in tilt, and 10 in half-angle. Our results quantitatively show the critical need for at least two viewpoints to be able to reduce the uncertainty in deriving CME parameters. We did not find a significant decrease in errors when going from two to three viewpoints for our specific hypothetical three spacecraft scenario using synthetic GCS white-light data. As we expected, considering all configurations and numbers of viewpoints, the mean absolute errors in the measured CME parameters are generally significantly higher in the case of the simulated MHD white-light data compared to those from the synthetic white-light images generated by the GCS model.

Space Science Reviews volume 217, Article number: 84 (2021) Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections (ICMEs) in the near-Earth environment. In many cases, these ICMEs can be traced back unambiguously to a specific coronal mass ejection (CME) and solar activity on the frontside of the Sun. Hence, predicting the arrival of ICMEs at Earth from routine observations of CMEs and solar activity currently makes a major contribution to the forecasting of geomagnetic storms. However, it is clear that some ICMEs, which may also cause enhanced geomagnetic activity, cannot be traced back to an observed CME, or, if the CME is identified, its origin may be elusive or ambiguous in coronal images. Such CMEs have been termed "stealth CMEs". In this review, we focus on these "problem" geomagnetic storms in the sense that the solar/CME precursors are enigmatic and stealthy. We start by reviewing evidence for stealth CMEs discussed in past studies. We then identify several moderate to strong geomagnetic storms (minimum Dst < -50 nT) in solar cycle 24 for which the related solar sources and/or CMEs are unclear and apparently stealthy. We discuss the solar and in situ circumstances of these events and identify several scenarios that may account for their elusive solar signatures. These range from observational limitations (e.g., a coronagraph near Earth may not detect an incoming CME if it is diffuse and not wide enough) to the possibility that there is a class of mass ejections from the Sun that have only weak or hard-to-observe coronal signatures. In particular, some of these sources are only clearly revealed by considering the evolution of coronal structures over longer time intervals than is usually considered. We also review a variety of numerical modelling approaches that attempt to advance our understanding of the origins and consequences of stealthy solar eruptions with geoeffective potential. Specifically, we discuss magnetofrictional modelling of the energisation of stealth CME source regions and magnetohydrodynamic modelling of the physical processes that generate stealth CME or CME-like eruptions, typically from higher altitudes in the solar corona than CMEs from active regions or extended filament channels.

Forecasting the arrival time of coronal mass ejections (CMEs) and their associated shocks is one of the key aspects of space weather. In recent years many models have been developed by various research groups aiming to forecast CME arrival time. The models differ based on the input, approach, assumptions and complexity ranging from simple empirical and analytical to complex numerical and machine learning models. One of the commonly used models is, due to its simplicity and calculation speed, the analytical drag-based (ensemble) model [DB(E)M] for heliospheric propagation of CMEs. DB(E)M relies on the observational fact that slow CMEs accelerate whereas fast CMEs decelerate, and is based on the concept of MHD drag, which acts to adjust the CME speed to the ambient solar wind. However, regardless of the model, forecasting CME arrival time has proven to be exceedingly challenging. One of the major setbacks is the uncertainty of the CME observational input, which is still substantial despite state-of-the-art remote observational capacities such as high-resolution EUV imagers and stereoscopic observations. Another major setback is the uncertainty in the CME propagation itself, due to e.g. unrealistic background solar wind and/or complex interactions. These limits will be discussed in the scope of DB(E)M and the CME input analysis performed by the ISSI Bern team on the "Understanding Our Capabilities In Observing And Modeling Coronal Mass Ejections".

Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and magnetic fields from the Sun. They are considered to be the main drivers of strong space weather events at Earth. Multiple models have been developed over the past decades to predict the propagation of CMEs and their possible arrival time at Earth. Such models require input from observations, which can be used to fit the CME to an appropriate structure.When determining parameters associated to the CME structure, it is common procedure to derive such kinematic parameters from remote-sensing data. The resulting parameters can be used as input for CME propagation models to obtain an arrival time prediction of the CME e.g. at Earth. However, different geometric structures and different parts of the CME structure can be fitted, and these aspects, together with the fact that most 3D reconstructions are performed by a scientist, creating a subjectivity of the fit, may lead to uncertainties in the fitted parameters. To our knowledge, so far, no large scale study has tried to map these uncertainties and how these affect the modelling of arrival time models.As a start for this work, we focused on the effect cause by the influence and subjectivty of the performing scientist. We have designed a synthetic situation where the true geometric parameters are known in order to quantify such uncertainties for the first time and discuss the results. We explore further work of the associated ISSI team.

Coronal Mass Ejections (CMEs) are the primary source of strong space weather disturbances at Earth and other locations in the heliosphere. Understanding the physical processes involved in their formation at the Sun, propagation in the heliosphere, and impact on planetary bodies is therefore critical to improve current space weather predictions throughout the heliosphere. It is known that the capability of individual CMEs to drive strong space weather disturbances at Earth (known as "geo-effectiveness") and other locations in the heliosphere (here referred to as "helio- effectiveness") primarily depends on their dynamic pressure, internal magnetic field strength, and magnetic field orientation at the impact location. At the same time, observational and modelling studies also established that CME-CME interactions can significantly alter the properties of individual CMEs, in such a way that their geo- effectiveness is often dramatically amplified. However, the actual quantification of this amplification has been rarely investigated, mostly via observational studies of individual events, or via explorative studies performed using idealized simulations of CME events, for which no truthful comparison with observations is possible. Additionally, the amplification effect of CME-CME interactions has been traditionally quantified only for the near-Earth region of space, without considering its full space-time evolution as the CMEs propagate to the Earth and beyond. In this work, we present a comprehensive study on the role of CME-CME interactions as sources of CME helio-effectiveness by performing simulations of complex CME events with the EUHFORIA heliospheric model. As a case study, we consider the sequence of CMEs observed during the unusually active week of 4-10 September 2017. As their source region rotated on the solar disk, CMEs were launched over a wide range of longitudes, interacting with each other and paving the way for the propagation of the following ones. CME signatures were observed at Mars and Earth, where an intense geomagnetic storm triggered by CME-CME interactions was recorded. Using input parameters derived from remote-sensing multi-spacecraft observations of the CMEs and their source region, we perform global simulations of magnetised CMEs with EUHFORIA. We investigate how their interactions affected the propagation and internal properties of individual CME structures, and their in-situ signatures at Earth and Mars. Taking advantage of 3D simulation outputs, we quantify the amplification of the helio- effectiveness of the individual CMEs involved, as a function of the interaction phase and of the location within the CME structure. Additionally, we also explore the possibility of the existence of a "helio-effectiveness amplification zone", i.e. a characteristic heliocentric distance at which CME-CME interactions have the highest probability to develop into highly helio-effective events. Results from this study benchmark our current prediction capabilities in the case of complex CME events, and provide insights on their large-scale evolution and potential impact throughout the heliosphere.

The Sun, besides being fundamental for life on Earth, is also characterised by intense activity and magnetism. Such activity manifests often in the form of eruptions, that can consist of large amounts of plasma and magnetic flux that are ejected into interplanetary space. These phenomena are known as coronal mass ejections (CMEs). CMEs may impact Earth and harm the performance and reliability of space- and ground-based technological systems, such as satellites in orbit, power grids, and systems utilising navigation and positioning applications. The increased radiation that follows a CME eruption can endanger the health of astronauts involved in space missions. The effects of solar activity on Earth are called collectively "space weather". The ability of a CME to drive space weather effects on Earth (or "geoeffectiveness") depends on its internal magnetic structure, morphology, and speed. The magnetic structure of a CME is often described with a flux rope morphology, that is a helical magnetic tube whose magnetic field can be divided into two main components: the axial field, which runs through the centre of the tube, and the helical field, which wraps around the tube. In this thesis, the magnetic structure of CMEs and their geoeffectiveness at 1 AU are investigated using a combination of observational and modelling techniques. The magnetic structure of flux ropes at the time of eruption can be inferred from multiwavelength remote-sensing observations of the CME source region, by taking into account features as coronal loops, filaments, flare ribbons, and photospheric structures. However, the results of the analysis show that the magnetic structure of such flux ropes may differ significantly when measured at 1 AU, i.e. around Earth’s orbit. This is because CMEs can experience dramatic evolution after lifting off from the Sun, e.g. through deflections, rotations, and deformations. The results presented in this thesis highlight that CME evolution is an important factor to take into account in numerical models and in space weather forecasting. Furthermore, the turbulent sheath regions that often travel ahead of CMEs may contain geoeffective components. Another aspect that contributes to making CME forecasting a challenging task is represented by those CMEs whose impact is less "obvious," e.g., because they are not entirely Earth-directed or because their signatures are unclear in remote-sensing data. During periods of significant solar activity there can be multiple CMEs launched from the same or nearby source regions. This thesis utilises recent multi-instrument observations from different vantage points to analyse periods of successive CME eruptions and their possible interactions in the corona and inner heliosphere. Magnetohydrodynamic modelling of CME propagation is also used, especially for problematic CMEs and multi-eruption periods, to provide a global heliospheric context necessary to interpret the multi-spacecraft observations. This thesis thus contributes to the improvement of our current understanding of CME evolution and space weather forecasting. Its results can be used as inputs, validation, and refinement for space weather forecasting tools and their modelling results. Finally, its comprehensive Sun–to–1 AU approach to analyse periods of enhanced eruptive activity and the subsequent heliospheric evolution of multiple CME events emphasises the importance of combining observations from multiple vantage points and heliospheric modelling for making progress in space weather forecasting. Koronan massapurkaukset (englanniksi Coronal Mass Ejections, CMEs) ovat Auringon koronasta purkautuvia suuria pilviä, jotka sisältävät valtavia määriä plasmaa ja magneettikenttää. CME:t voivat osua Maahan ja ne ovat kaikkein tehokkaimpia myrskyjen ajajia Maan lähiavaruudessa. Magneettisen myrskyn aikana teknologisten systeemien toimintakyky ja -varmuus niin avaruudessa kuin Maassa voi merkittävästi häiriintyä. Lisäksi lisääntynyt säteily voi vaarantaa avaruuslennoilla olevien astronauttien terveyden. CME:iden kyky aiheuttaa magneettisia myrskyjä (tai "geoefektiivisyys") riippuu niiden magneettisesta rakenteesta, muodosta, ja nopeudesta. CME:t kuvataan usein magneettisiksi "vuoköysiksi", joiden magneettikentän voidaan katsoa koostuvan kahdesta pääkomponentista: vuoköyden akselin suuntaisesta pitkittäisestä kentän komponentista ja sitä kohtisuorassa olevasta vuoköyden akselin ympärille kiertyvästä komponentista. Tässä väitöskirjassa tutkitaan CME:iden magneettista rakennetta ja geoefektiivisyyttä Maan kiertoradan etäisyydellä Auringosta käyttämällä sekä havaintoja että mallinnusta. Vuoköyden magneettinen rakenne purkauksen aikana voidaan päätellä yhdistämällä usean aallonpituuden kaukohavaintoja CME:n lähdealueesta Auringossa, mm. tarkastelemalla koronan kaaria, filamentteja, roihunauhoja ja fotosfäärin rakenteita. Väitöskirjassa suoritettu analyysi osoittaa kuitenkin, että aurinkohavainnoista päätelty vuoköyden rakenne poikkeaa usein merkittävästi Maan kiertoradalla havaitusta rakenteesta. Tämä johtuu CME:n merkittävästä kehityksestä planeettainvälisessä avaruudessa sen purkautumisen jälkeen, esimerkiksi CME:n kulkusuunnan muutoksista, pyörimisestä ja rakenteen muutoksista. Lisäksi haasteellisia avaruussääennustamiselle ovat ne purkaukset, joiden törmäys Maahan ei ole selvää aurinkohavaintojen perusteella. Näitä ovat mm. CME:t jotka eivät etene suoraan Maata kohti ja jotka ovat epäselviä kaukohavainnoissa. Myös CME:n edellään ajama turbulentti sheath-alue voi aiheuttaa magneettisia myrskyjä. Väitöskirjassa analysoitiin säännöllisiä suuren mittakaavan magneettisia rakenteita sheath-alueissa ja saadut tulokset auttavat arvioimaan paremmin sheath-alueiden geoefektiivisyyttä. Korkean Auringon aktiivisuuden aikana useita CME:itä voi myös lähteä peräkkäin samasta lähdealueesta. Väitöskirjassa hyödynnetään uusimpia havaintoja laajalta aallonpituusalueelta ja useista havaintopisteistä analysoimaan peräkkäisiä CME-purkauksia ja niiden vuorovaikusta Auringon koronassa ja planeettainvälisessä avaruudessa. Tutkimuksessa käytettiin myös näiden ongelmallisten CME-tapausten analysoimiseen magnetohydrodynaamista heliosfäärin simulaatiota. Simulaatiot antavat globaalin kontekstin tulkita satelliittihavaintoja useista mittauspaikoista. Väitöskirjan tulokset painottavat CME:n kehityksen merkittävyyttä numeerisille malleille ja avaruusään ennustamiselle. Työn tuloksia voidaan käyttää alkuarvoina avaruussäämalleissa, sekä niiden validoimiseen, että kehittämiseen. Lisäksi työ korostaa useiden erilaisten havaintojen ja havaintopisteyden tärkeyttä avaruussääennustamiselle, varsinkin monimutkaisten ja vuorovaikuttavien CME:iden tapauksessa.

Coronal mass ejections (CMEs) and solar energetic particles (SEPs) are two phenomena that can cause severe space weather effects throughout the heliosphere. The evolution of CMEs, especially in terms of their magnetic structure, and the configuration of the interplanetary magnetic field (IMF) that influences the transport of SEPs are currently areas of active research. These two aspects are not necessarily independent of each other, especially during solar maximum when multiple eruptive events can occur close in time. Accordingly, we present the analysis of a CME that erupted on 2012 May 11 (SOL2012-05-11) and an SEP event following an eruption that took place on 2012 May 17 (SOL2012-05-17). After observing the May 11 CME using remote-sensing data from three viewpoints, we evaluate its propagation through interplanetary space using several models. Then, we analyse in-situ measurements from five predicted impact locations (Venus, Earth, the Spitzer Space Telescope, the Mars Science Laboratory en route to Mars, and Mars) in order to search for CME signatures. We find that all in-situ locations detect signatures of an SEP event, which we trace back to the May 17 eruption. These findings suggest that the May 11 CME provided a direct magnetic connectivity for the efficient transport of SEPs. We discuss the space weather implications of CME evolution, regarding in particular its magnetic structure, and CME-driven IMF preconditioning that facilitates SEP transport. Finally, this work remarks the importance of using data from multiple spacecraft, even those that do not include space weather research as their primary objective., Comment: 50 pages, 14 figures, 2 tables, accepted for publication in Space Weather