Much of our knowledge about the large-scale structure and variations of
the solar wind, interplanetary magnetic field (IMF), transients (coronal
mass ejections, shocks) and energetic particles in the inner heliosphere
(< 2 AU) was gained from multi-spacecraft in-situ measurements,
especially from missions such as Helios and STEREO as well as
conjunctions between spacecraft at various planets. We have also gained
some knowledge of structures and variability in the interplanetary space
associated with turbulence, waves and instabilities on much smaller
scales thanks to ACE, Wind and ARTEMIS as well as MMS, while their
properties on intermediate (meso) scales is yet mostly unknown. The aim
of this session is to discuss progress in our understanding of CMEs,
CIRs, shocks, SEPs, the IMF and solar wind made thanks to
multi-spacecraft measurements on various scales ranging from a fraction
of an earth radius to 1 AU and the way forward. This session invites
abstracts related to analyses and simulations of multi-spacecraft
measurements in the inner heliosphere. It is especially interested in
in-situ measurements made possible by STEREO (which will be within 60
degrees of the Sun-Earth line by the end of 2020), Solar Probe, Solar
Orbiter and missions near L1, planetary missions (MESSENGER,
BepiColombo, MAVEN) as well as future missions, concepts and
instrumentation to investigate the various scales in interplanetary

Convener: Harald Kucharek | Co-conveners: Charles Farrugia, Benoit Lavraud, Noé Lugaz, Alessandro Retinò
| Attendance Mon, 04 May, 16:15–18:00 (CEST)

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Chat time: Monday, 4 May 2020, 16:15–18:00

D3069 |
Simon Good, Matti Ala-Lahti, Erika Palmerio, Emilia Kilpua, and Adnane Osmane

The sheaths of compressed solar wind that precede interplanetary coronal mass ejections (ICMEs) commonly display large-amplitude magnetic field fluctuations. As ICMEs propagate radially from the Sun, the properties of these fluctuations may evolve significantly. We present a case study of an ICME sheath observed by a pair of radially aligned spacecraft at around 0.5 and 1 AU from the Sun. Radial changes in fluctuation amplitude, compressibility, inertial-range spectral slope, permutation entropy, Jensen-Shannon complexity, and planar structuring are characterised.  We discuss the extent to which the observed evolution in the fluctuations is similar to that of solar wind emanating from steady sources at quiet times, how the evolution may be influenced by evolving local factors such as leading-edge shock orientation, and how the perturbed heliospheric environment associated with ICME propagation may impact the evolution more generally.

How to cite: Good, S., Ala-Lahti, M., Palmerio, E., Kilpua, E., and Osmane, A.: Radial evolution of magnetic field fluctuations in an ICME sheath, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13664, https://doi.org/10.5194/egusphere-egu2020-13664, 2020.

D3070 |
Emilia Kilpua, Simon Good, Erika Palmerio, Eleanna Asvestari, Jens Pomoell, Erkka Lumme, Matti Ala-Lahti, Milla Kalliokoski, Diana Morosan, Daniel Price, Jasmina Magdalenic, Stefaan Poedts, and Yoshimi Futaana

Interactions between coronal mass ejections (CMEs) in interplanetary space are a highly important aspect for understanding their physical dynamics and evolution as well as their space weather consequences. Here we present an analysis of three CMEs that erupted from the Sun on June 12-14, 2012 using almost radially aligned spacecraft at Venus and Earth, complemented by heliospheric imaging and modelling with EUHFORIA. These multi-spacecraft observations were critical for interpreting the event correctly, in particular regarding the last two CMEs in the series (June 13 and June 14). At the orbit of Venus these CMEs were mostly separate with the June 14 CME just about to reach the previous CME. A significant interaction occurred before the CMEs reached the Earth. The shock of the June 14 CME had propagated through the June 13 CME and the two CMEs had coalesced into a single large flux rope structure before they reached the Earth. This merged flux rope had one of the largest magnetic field magnitudes observed in the near-Earth solar wind during Solar Cycle 24. We discuss also the general importance of multi-spacecraft observations and modelling using them in analyzing solar eruptions.

How to cite: Kilpua, E., Good, S., Palmerio, E., Asvestari, E., Pomoell, J., Lumme, E., Ala-Lahti, M., Kalliokoski, M., Morosan, D., Price, D., Magdalenic, J., Poedts, S., and Futaana, Y.: Multi-spacecraft Observations of interacting CME flux ropes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6043, https://doi.org/10.5194/egusphere-egu2020-6043, 2020.

D3071 |
Zdeněk Němeček, Tereza Ďurovcová, Jana Šafránková, Jiří Šimůnek, John D. Richardson, and Jaroslav Urbář

The solar wind aberration due to non-radial velocity components and the Earth orbital motion is important for the overall magnetosphere geometry because the magnetospheric tail is aligned with the solar wind flow. This paper investigates an evolution of non-radial components of the solar wind flow along the path from the Sun to 6 AU. A comparison of observations at 1 AU and closer to or further from the Sun based on measurements of many spacecraft at different locations in the heliosphere (Wind, ACE, Spektr-R, THEMIS B and C, Helios 1 and 2, Mars-Express, Voyager 1 and 2) shows that (i) the average values of non-radial components vary with the distance from the Sun and (ii) they differ according to solar wind streams.

How to cite: Němeček, Z., Ďurovcová, T., Šafránková, J., Šimůnek, J., Richardson, J. D., and Urbář, J.: (Non)-radial propagation of the solar wind flow , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2736, https://doi.org/10.5194/egusphere-egu2020-2736, 2020.

D3072 |
Zoltan Vörös, Emiliya Yordanova, Owen Roberts, and Yasuhito Narita

Twisted magnetic flux ropes embedded in an interplanetary coronal mass ejection (ICME) often contain oppositely oriented magnetic fields and potentially reconnecting current sheets. Reconnection outflows in the solar wind can be identified through magnetic field and plasma signatures, for example, through decreasing magnetic field magnitude, enhanced bulk velocity, temperature and (anti)correlated rotations of the magnetic field and plasma velocity. We investigate a reconnection outflow observed by ACE, WIND and Geotail spacecraft within the interaction region of two flux ropes embedded into an ICME. The SOHO spacecraft, located 15 RE upstream, 120 RE in GSE Y and 5 RE in GSE Z direction from the ACE spacecraft, does not see any plasma signatures of the reconnection outflow. At the same time the other spacecraft, also separated by more than 200 RE in X and Y GSE directions, observe strong plasma and magnetic field fluctuations at the border of the exhaust.  The fluctuations could be associated with Kelvin-Helmholtz (KH) instability at the border of the reconnection outflow with strong flow shear.  It is speculated that the KH instability driven fluctuations and dissipation is responsible for stopping the reconnection outflow which is therefore not seen by SOHO.

How to cite: Vörös, Z., Yordanova, E., Roberts, O., and Narita, Y.: Multi-point observations of a reconnection outflow associated with interacting flux ropes in the solar wind, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8621, https://doi.org/10.5194/egusphere-egu2020-8621, 2020.

D3073 |
Thomas Neukirch, Ivan Vasko, Anton Artemyev, and Oliver Allanson

Current sheets in the collisionless solar wind usually have kinetic spatial scales. In-situ measurements (e.g. by Artemis) show that these current sheets are often approximately force-free, i.e. the directions of their current density and magnetic field are aligned, despite the fact that the plasma β is found to be of the order of one. The measurements also often show systematic asymmetric spatial variations of the plasma density and temperature across the current sheets, whilst the plasma pressure is approximately uniform. We present analytical equilibrium distribution functions of self-consistent force-free collisionless current sheets which allow for asymmetric plasma density and temperature gradients.

How to cite: Neukirch, T., Vasko, I., Artemyev, A., and Allanson, O.: Kinetic models of current sheets in the solar wind, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18966, https://doi.org/10.5194/egusphere-egu2020-18966, 2020.

D3074 |
Athanasios Kouloumvakos and Alexis P. Rouillard

STEREO has provided over 10 yr of continuous monitoring of CMEs and CME-driven shock waves from the Sun to Earth-like distances, as well as multipoint measurements of SEPs in the keV to 100 MeV energy range. These observations have revealed a number of puzzling properties of SEPs. For instance, gradual and impulsive SEP events have been measured over extended ranges of longitudes by STEREO, sometimes extending over 360 degrees around the Sun. Multi-spacecraft remote-sensing observations have allowed us to perform shock wave modeling in 3D, and to derive and examine consistently critical shock parameters during their evolution. I will present a connection of the shocks/CMEs to SEP properties from multi-spacecraft in-situ measurements by alleviating projection effects, accounting for both the complexities of coronal shocks and how they are likely to connect magnetically with in-situ spacecraft. A comparison between the shock wave parameters derived from 3D modeling and observations, and SEP characteristics confirm predictions of diffusive shock acceleration, that efficient acceleration of SEPs should naturally occur at shock regions where the shock Mach number is high. I will also discuss how modeling shock waves and estimating their magnetic connectivity can be useful in future studies to determine the solar origin of particle events measured by Parker Solar Probe.

How to cite: Kouloumvakos, A. and Rouillard, A. P.: Shock wave properties in the solar corona and their associations with multi-spacecraft solar energetic particle events measured near 1AU., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11889, https://doi.org/10.5194/egusphere-egu2020-11889, 2020.

D3075 |
Zigong Xu, Robert F Wimmer-Schweingruber, Jingnan Guo, Jia Yu, Shenyi Zhang, Thomas Berger, Daniel Matthiae, Soenke Burmeister, Stephan Boettcher, and Bernd Heber

After Chang’E 4 successfully landed on the far side of the moon on Jan 3rd, 2019, the Lunar Lander Neutron and Dosimetry experiment has been working for 13 lunar days from January, 2019 to January, 2020, sending back the measurements of dose, linear energy transfer (LET) spectrum, neutrons, and charged particles. Here, we show observations of charged particles especially protons and Helium ions during quiet time. We also present two solar energetic particle events registered by LND in May 2019, which are also the first such measurements on the far-side surface of the moon. The temporal variations of particle fluxes on the far side of the moon detected by LND provide a new observation site in space and can be helpful to improve our understanding of particle propagation and transport in the heliosphere.


How to cite: Xu, Z., Wimmer-Schweingruber, R. F., Guo, J., Yu, J., Zhang, S., Berger, T., Matthiae, D., Burmeister, S., Boettcher, S., and Heber, B.: Energetic particles measurements on the lunar far-side by Lunar Lander Neutron and Dosimetry(LND) experiment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21246, https://doi.org/10.5194/egusphere-egu2020-21246, 2020.

D3076 |
Anna Salohub, Jana Šafránkova, Zdeněk Němeček, Lubomír Přech, and Tereza Ďurovcová

The solar wind variations during particular solar cycles have been described in many previous studies including the solar cycle 23 that was characterized by a long, deep, and very complex solar minimum with very low values of many solar wind parameters.

Using statistical methods, we analyzed 25 years of Wind spacecraft measurements with motivation to reveal differences and similarities in magnetic field components and solar wind plasma parameters in individual solar cycles. We tracked the changes of the solar magnetic field strength, and components, solar wind speed, density, dynamic pressure, temperature, and composition). Except quiet solar wind conditions during solar minima and maxima, we also selected significant discontinuities (ICME and CIRs) and investigated their influence on profiles of average parameters. For this, we followed other quantities connected with their presence as their average front normals, regions of transitions between high and slow wind streams, special interplanetary magnetic field orientations, etc.). We discuss a behavior of investigated parameters over solar cycles as well as on shorter time scales (in the order of days and hours).

How to cite: Salohub, A., Šafránkova, J., Němeček, Z., Přech, L., and Ďurovcová, T.: Long-term properties of the solar wind and their relation to solar cycles, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3690, https://doi.org/10.5194/egusphere-egu2020-3690, 2020.

D3077 |
Štěpán Štverák, Milan Maksimovic, Petr Hellinger, and Pavel M. Trávníček

Our understanding of the solar wind evolution, its energy budget, and role of the key mechanisms providing the energy exchange between the plasma particles and electromagnetic fluctuations along the expansion, is highly limited by the single point nature of most in situ spacecraft measurements. Obviously it is difficult to observe and track the individual processes in space and time from this narrow perspective. One way to improve our knowledge of these large-scale variations is to employ multi-spacecraft observations, namely rather rare so called line-up events where one can potentially observe the true evolution of individual solar wind plasma parcels. A pioneering work in this field was done using Helios I&II missions. Here we present an analyses of using such tool for future events predicted to be available from the very recent missions Parker Solar Probe and Solar Orbiter (and optionally BepiColombo).

How to cite: Štverák, Š., Maksimovic, M., Hellinger, P., and Trávníček, P. M.: Solar wind radial evolution via future multi-spacecraft in-situ observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7451, https://doi.org/10.5194/egusphere-egu2020-7451, 2020.

D3078 |
Tarik Salman, Reka Winslow, and Noé Lugaz

Our knowledge of the properties of Coronal Mass Ejections (CMEs) in the inner heliosphere is constrained by the relative lack of plasma observations between the Sun and 1 AU. In this work, we present a comprehensive catalog of 47 CMEs measured in situ measurements by two or more radially aligned spacecraft (MESSENGER, Venus Express, STEREO, and Wind/ACE). We estimate the CME impact speeds at Mercury and Venus using a drag-based model and present an average propagation profile of CMEs (speed and deceleration/acceleration) in the inner heliosphere. We find that CME deceleration continues past Mercury's orbit but most of the deceleration occurs between the Sun and Mercury. We examine the exponential decrease of the maximum magnetic field strength in the CME with heliocentric distance using two approaches: a modified statistical method and analysis from individual conjunction events. Findings from both the approaches are on average consistent with previous studies but show significant event-to-event variability. We also find the expansion of the CME sheath to be well fit by a linear function. However, we observe the average sheath duration and its increase to be fairly independent of the initial CME speed, contradicting commonly held knowledge that slower CMEs drive larger sheaths. We also present an analysis of the 3 November 2011 CME observed in a longitudinal conjunction between MESSENGER, Venus Express, and STEREO-B focusing on the expansion of the CME and its correlation with the exponential fall-off of the maximum magnetic field strength in the ejecta.

How to cite: Salman, T., Winslow, R., and Lugaz, N.: Radial Evolution of Coronal Mass Ejections in the Inner Heliosphere: Catalog and Analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4009, https://doi.org/10.5194/egusphere-egu2020-4009, 2020.

D3079 |
Matti Ala-Lahti, Julia Ruohotie, Simon Good, Emilia Kilpua, and Noé Lugaz

We report on the longitudinal coherence of sheath regions driven by interplanetary coronal mass ejections (ICMEs). ICME sheaths are significant drivers of geomagnetic activity at the Earth, with a considerable fraction of ICME-driven storms being either entirely or primarily induced by the sheath. Similarly to Lugaz et al. (2018; doi:10.3847/2041-8213/aad9f4), we have analyzed two-point magnetic field measurements made by the ACE and Wind spacecraft in 29 ICME sheaths to estimate the coherence scale lengths, defined as the spatial scale at which correlation between measurements falls to zero, of the field magnitude and components. Scale lengths for the sheath are found to be mostly smaller than the corresponding values in the ICME driver, an expected result given that ICME sheaths are characterized by highly fluctuating, variable magnetic fields, in contrast to the often more coherent ejecta. A relatively large scale length for the magnetic field component in the GSE y-direction was found. We discuss how magnetic field line draping around the ejecta and the alignment of pre-existing magnetic structures by the preceding shock may explain the observed results. In addition, we consider the existence of longitudinally extended and possibly geoeffective magnetic field fluctuations within ICME sheaths, the full understanding of which requires further multi-spacecraft analysis.

How to cite: Ala-Lahti, M., Ruohotie, J., Good, S., Kilpua, E., and Lugaz, N.: Spatial coherence of interplanetary coronal mass ejection-driven sheaths at 1 AU, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13474, https://doi.org/10.5194/egusphere-egu2020-13474, 2020.

D3080 |
Mojtaba Akhavan-Tafti, Dominique Fontaine, Olivier Le Contel, and James Slavin

The most geoeffective storms in the Space Age have been driven solely by the sheath preceding an interplanetary coronal mass ejection (ICME) or by a combination of the sheath and an ICME magnetic cloud. In the present study, the magnetospheric response to a chain of three independent and well-spaced ICMEs (Pdyn > 15 nPa and Sym-H < -50 nT) spanning one month (December 12, 2015 – January 12, 2016) is investigated using WIND, Cluster, and MMS fields and plasma measurements. The first of the three ICMEs consists of a sheath preceding an ICME (ICME-SH). The latter two ICMEs are preceded by a combination of the sheath and an ICME magnetic cloud (ICME-SH-MC).

Following the passage of the first ICMEs (ICME-SH) the interplanetary environment was made up of moderate Alfvenic Mach number (MA ~ 10) and average magnetopause standoff distance (RMP ~ 11 RE). The arrival of the ICME-SH-MC then initiated a sudden storm commencement (SSC) phase. During the SSC, the storm index (Sym-H ~ +50 nT) remained positive through the ICME shock and sheath regions. The storm index and the Alfvenic Mach number sharply declined (Sym-H~ -200 nT and MA ~ 1.0, respectively) with the arrival of the leading edge of the magnetic cloud (BIMF, core ~ 20 nT) and the associated sharp IMF Bz reversal (Bz<0). The Alfvenic Mach number and IMF Bz are found to directly correlate with the Sym-H index. ICME-SH-MC compressed the magnetopause standoff distance (∂RMP/∂t ~ -1 RE/min), resulting in a sudden reduction in the total magnetospheric volume (∂VMP/∂t ~ -3×102 RE3/min), as determined by cross-scale observations. In particular, the sharp drops in the magnetospheric volume (relative change in volume >30%) with the arrival of each of the three independent ICMEs are shown to start with the SSC and remain low through the main phase, before slowly recovering (∂VMP/∂t ~ +1 RE3/min) to the pre-ICME conditions during the recovery phase.

How to cite: Akhavan-Tafti, M., Fontaine, D., Le Contel, O., and Slavin, J.: Geomagnetic Response to a Chain of Interplanetary Coronal Mass Ejections, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10717, https://doi.org/10.5194/egusphere-egu2020-10717, 2020.

D3081 |
Harald Kucharek, Matthew Young, Noe Lugaz, Charles Farrugia, Steven Schwartz, and Karlheinz Trattner

Turbulent fluctuations in the magnetic field and in the bulk plasma parameters of the solar wind have important effects on the propagation and evolution of energetic particles throughout the heliosphere and on the coupling of the solar wind to the Earth's magnetosphere. At the shock the solar wind kinetic energy is converted into downstream plasma heating, ion reflection and acceleration. Changes in upstream plasma conditions can result in changes in the dynamics of the shock, its structure, and the suprathermal ion population it generates. These upstream variations can be due to transients, interplanetary shocks, and other discontinuities. They can also result from nonlinear interactions, causing an intermittent energy dissipation and leading to possible currents sheet structures. A number of these events can be found in observations from STEREO (for interplanetary traveling shocks) and CLUSTER/MMS (for the Earth’s bow shock) in the magnetosheath. 

We performed 3D-hybrid simulations to study the effects of spatially confined disturbances, such as density enhancements, depletions, and current layers/sheets and studied the shock dynamics, and the energetic particle release at various distances from the bow shock. The results of these simulations are then discussed in terms of multi-spacecraft observations in the magnetosheath at various scales.  The results show that shock reformation is highly impacted by density depressions/enhancements and so is the generation of waves and suprathermal ions. Also, upstream solar wind variations can alter the shock properties considerably at the various virtual spacecraft in the simulations.

How to cite: Kucharek, H., Young, M., Lugaz, N., Farrugia, C., Schwartz, S., and Trattner, K.: The Effect of Variable Solar Wind Conditions on the Bow Shock Structure and its Ability to Generate Energetic Ions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11070, https://doi.org/10.5194/egusphere-egu2020-11070, 2020.

D3082 |
Yuri Yermolaev, Irina Lodkina, Lidia Dremukhina, Michael Yermolaev, and Alexander Khokhlachev

Although the main types of solar wind (the so-called interplanetary drivers), which may contain the southward component of the interplanetary magnetic field (Bz <0) and cause disturbances in the magnetosphere, have long been known, it has only recently been discovered that different types of drivers cause a different reaction of the magnetosphere for identical field variations (Borovsky and Denton,2006, Yermolaev et al., 2013). This discovery led to a significant increase in the number of investigations studying the response of the magnetosphere-ionosphere system to various drivers. At the same time, the number of incorrect approaches in this direction of research has increased. These errors can be attributed to 4 large classes. (1) First class includes works whose authors uncritically reacted to previously published works and use incorrect results to identify types of drivers. (2) Some authors independently incorrectly identified driver types. (3) Very often, authors associate the perturbation of the magnetosphere-ionosphere system caused by a complex driver (a sequence of single drivers) with one of the drivers, ignoring the complex nature. For example, a magnetic storm is often caused by a compression region Sheath in front of an interplanetary CME (ICME), but the authors consider the ICME to be a cause of disturbance, not Sheath. (4) Finally, there is a “lost driver” of magnetospheric disturbances: some authors simply do not consider the Sheath compression region before ICME if there is no interplanetary shock (IS) before Sheath, although this type of driver, “Sheath without IS”, generates about 10% of moderate and strong geomagnetic storms (Yermolaev et al., 2017, 2020). These errors lead to numerous mistakes and incorrect conclusions.
The work is supported by the RFFI grant 19-02-00177а. 

Borovsky, J. E., and M. H. Denton (2006), Differences between CME‐driven storms and CIR‐driven storms, J. Geophys. Res., 111, A07S08, doi:10.1029/2005JA011447

Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2012), Geoeffectiveness and efficiency of CIR, sheath, and ICME in generation of magnetic storms, J. Geophys. Res., 117, A00L07, doi:10.1029/2011JA017139

Yermolaev, Y.I., Lodkina, I.G., Nikolaeva, N.S. et al. (2017), Some problems of identifying types of large-scale solar wind and their role in the physics of the magnetosphere, Cosmic Res. 55: 178. https://doi.org/10.1134/S0010952517030029

Yermolaev, Y.I., Lodkina, I.G., et al. (2020), Some problems of identifying types of large-scale solar wind and their role in the physics of the magnetosphere. 4. Lost driver, Cosmic Res. 59, in press


How to cite: Yermolaev, Y., Lodkina, I., Dremukhina, L., Yermolaev, M., and Khokhlachev, A.: A critical look at studying the interplanetary drivers of the magnetospheric disturbances , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4064, https://doi.org/10.5194/egusphere-egu2020-4064, 2020.

D3083 |
Emma Davies, Robert Forsyth, and Simon Good

Understanding the evolution of interplanetary coronal mass ejections (ICMEs) as they propagate through the heliosphere is essential in forecasting space weather severity. Much of our knowledge of ICMEs has been gained using in-situ measurements from single spacecraft, although the increasing number of missions in the inner heliosphere has led to an increase in multi-spacecraft studies improving our understanding of the global structure of ICMEs. Whilst most such recent studies have focused on the inner heliosphere within 1 AU, Juno cruise phase data provides a new opportunity to study ICME evolution over greater distances. We present analysis of ICMEs observed in-situ both by Juno and at least one other spacecraft within 1 AU to investigate their evolution as they propagate through the heliosphere. Investigation of the sheath region and timing considerations between spacecraft allows for the general shape of the shock front to be reconstructed. Combining in-situ observations and results of flux rope fitting techniques determines the global picture of the ICME as it propagates. However, effects on in-situ observations due to radial evolution and due to the longitudinal separation between multi-spacecraft remain hard to separate. We note the importance of the interplanetary environment in which the ICME propagates and the need for caution in radial alignment studies.  

How to cite: Davies, E., Forsyth, R., and Good, S.: Using In-Situ Juno Observations to Understand the Evolution of Interplanetary Coronal Mass Ejections Within 1 AU and Beyond , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13767, https://doi.org/10.5194/egusphere-egu2020-13767, 2020.

D3084 |
Lina Hadid, Melinda Dosa, Madar Akos, Tommaso Alberti, Johannes Benkhoff, Zsofia Bebesi, Lea Griton, George C. Ho, Kazumasa Iwai, Miho Janvier, Anna Milillo, Yoshizumi Miyoshi, Daniel Mueller, Go Murukami, Jim M. Raines, Daikou Shiota, Andrew Walsh, Joe Zender, and Yannis Zouganelis

BepiColombo and Solar Orbiter are two spacecraft that will be both travelling in the inner heliosphere for 5 years, between the launch of Solar Orbiter (planned in February 2020) and the end of the cruise phase of BepiColombo (2018 - 2025). Both BepiColombo (ESA/JAXA) and Solar Orbiter (ESA/NASA) are carrying exceptional and complementary plasma instrumental payloads and magnetometers. Besides, the remote-sensing instruments on board of Solar Orbiter will provide invaluable information on the state of the Sun, and therefore some contextual information for BepiColombo observations. During the five years to come, BepiColombo will evolve between the Earth and the orbit of Mercury, while Solar Orbiter’s highly elliptical orbit will cover distances from 1.02 AU to 0.28 AU.  We present here the scientific cases, modelling tools, measurement opportunities and related instruments operations that have been identified in the frame of potential coordinated observations campaign between the spacecraft.

How to cite: Hadid, L., Dosa, M., Akos, M., Alberti, T., Benkhoff, J., Bebesi, Z., Griton, L., C. Ho, G., Iwai, K., Janvier, M., Milillo, A., Miyoshi, Y., Mueller, D., Murukami, G., M. Raines, J., Shiota, D., Walsh, A., Zender, J., and Zouganelis, Y.: BepiColombo and Solar Orbiter coordinated observations: scientific cases and measurements opportunities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17957, https://doi.org/10.5194/egusphere-egu2020-17957, 2020.

D3085 |
Rachel Bailey, Christian Moestl, Martin Reiss, Andreas Weiss, Ute Amerstorfer, Tanja Amerstorfer, Juergen Hinterreiter, and Maike Bauer

STEREO-B and STEREO-A are both important proxies for potential solar wind monitors at the Sun-Earth L5 point. In this study, measurements from STEREO-B are used to determine how well the Dst index in particular can be predicted using data measured near the L5 point. This is useful for determining the geoeffectivity of storms resulting from high-speed solar wind streams. Observed solar wind speeds are first mapped to the near-Earth environment as if they had been measured at L1, and the Dst is predicted from the data using a solar wind-to-Dst model. We find that Dst predicted from L5 data performs better than a recurrence model assuming the solar wind conditions repeat every 27 days, although not as well as when predicted from L1 data. The newly developed approach is currently implemented in the PREDSTORM software package to provide a real-time Dst forecast using STEREO-A data.

How to cite: Bailey, R., Moestl, C., Reiss, M., Weiss, A., Amerstorfer, U., Amerstorfer, T., Hinterreiter, J., and Bauer, M.: Forecasting the Dst index from L5 in-situ data using PREDSTORM: accuracy and applicability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7892, https://doi.org/10.5194/egusphere-egu2020-7892, 2020.

D3086 |
Yutian Chi, Chris Scott, Chenglong Shen, and Yuming Wang
Coronal mass ejections (CME) are large-scale eruptions of magnetized plasma and huge energy through the corona and out into interplanetary space.
A mount of CMEs observed by HI-1 cameras present two fronts that are similar in shape but separated by a few degrees in elongation. Scott et al. (2019) interpret the ghost fronts as projections of separate discrete sections of the physical boundary of the  CME. Ghost fronts could provide information about the longitudinal shape of CME in the field of view of Hi- 1, which can be used to improve the forecast of the arrival time of ICME. During 13-15 June 2012, STEREO/SECCHI recorded two successive launched Earth-directed CMEs. Both of the two CMEs show clearly two fronts in HI-1 images. We use the ghost fronts to predict the arrival time of the two CMEs and utility the in-situ measurements from VEX and Wind to verify the accuracy of the prediction of ghost fronts model. 

How to cite: Chi, Y., Scott, C., Shen, C., and Wang, Y.: Using Ghost Fronts to Predict the Arrival Time of CMEs during 13-17 June 2012, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2446, https://doi.org/10.5194/egusphere-egu2020-2446, 2020.

D3087 |
Matteo Martucci and the CSES-Limadou Collaboration

The China Seismo-Electromagnetic Satellite (CSES-01) is a mission developed by

the Chinese National Space Administration (CNSA) together with the Italian Space Agency (ASI), to investigate the near-Earth electromagnetic, plasma and particle environment. In addition, it has been designed to detect a wide number of disturbances of the ionosphere/magnetosphere transition region.

One of the main instruments on-board CSES-01 is the High Energy Particle Detector (HEPD); it is an advanced detector, completely designed and built in Italy, based on a tower of 16 scintillators and a silicon tracker that provides good energy resolution and a wide angular acceptance for electrons/positrons (3–100 MeV), protons (30–200 MeV) and light nuclei up to Oxygen.

The very good capabilities in particle detection and separation make the detector extremely well suited for Space Weather purposes;  being also able to continuously monitor the magnetospheric environment with high stability in time, HEPD can detect small variations related to transient phenomena taking place on the Sun and propagating through the solar wind.
After two years of data-taking, HEPD showed impressive capabilities in measuring the various particle distributions along its orbit, starting from sub-cutoff protons/electrons, up to galactic cosmic ray particles at higher latitudes. The former class includes both stably-trapped particles in the Radiation Belts and particles bounced back from the top of the atmosphere without being able to escape the magnetic trap (re-entrant albedo). For cosmic ray particles, precise measurements of their spectra are needed to understand the acceleration and subsequent propagation of low-energy particles in the inner sector of the heliosphere and, more general, in our Galaxy.

We report precision measurements of the protons in the >30 MeV energy region and electrons in the >5 MeV energy range, performed by HEPD in a un-disturbed heliosphere during a low solar activity period (2018/2020).

How to cite: Martucci, M. and the CSES-Limadou Collaboration: Observations and results from the High-Energy Particle Detector (HEPD) on-board CSES-01 satellite, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6750, https://doi.org/10.5194/egusphere-egu2020-6750, 2020.