Constraining the CME parameters of the spheromak flux rope implemented in EUHFORIA

2021 ◽  
Author(s):  
Eleanna Asvestari ◽  
Jens Pomoell ◽  
Emilia Kilpua ◽  
Simon Good ◽  
Theodosios Chatzistergos ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Space Weather ◽  
Weather Forecasting ◽  
Interplanetary Space ◽  
Source Region ◽  
Flux Rope ◽  
Field Configuration ◽  
Arrival Times ◽  
Sheath Region ◽  
Region Length

<p>Coronal mass ejections (CMEs) are primary drivers of space weather phenomena. Modelling the evolution of the internal magnetic field configuration of CMEs as they propagate through the interplanetary space is an essential part of space weather forecasting. EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is a data-driven, physics-based model, able to trace the evolution of CMEs and CME-driven shocks through realistic background solar wind conditions. It employs a spheromak-type magnetic flux rope that is initially force-free, providing it with the advantage of modelling CME as magnetised structures. For this work we assessed the spheromak CME model employed in EUHFORIA with a test CME case study. The selected CME eruption occurred on the 6th of January 2013 and was encountered by two spacecraft, Venus Express and STEREO--A, which were radially aligned at the time of the CME passage. Our focus was to constrain the input parameters, with particular interest in: (1) translating the angular widths of the graduated cylindrical shell (GCS) fitting to the spheromak radius, and (2) matching the observed magnetic field topology at the source region. We ran EUHFORIA with three different spheromak radii. The model predicts arrival times from half to a full day ahead of the one observed <em>in situ</em>. We conclude that the choice of spheromak radius affected the modelled magnetic field profiles, their amplitude, arrival times, and sheath region length.</p>

scholarly journals A new technique for observationally derived boundary conditions for space weather

2018 ◽  
Vol 8 ◽  
pp. A26 ◽  
Author(s):  
Paolo Pagano ◽  
Duncan Hendry Mackay ◽  
Anthony Robinson Yeates
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Boundary Conditions ◽  
Space Weather ◽  
Weather Forecasting ◽  
Interplanetary Space ◽  
Time Dependent ◽  
Magnetic Flux Ropes ◽  
Mhd Simulations ◽  
Flux Ropes

Context. In recent years, space weather research has focused on developing modelling techniques to predict the arrival time and properties of coronal mass ejections (CMEs) at the Earth. The aim of this paper is to propose a new modelling technique suitable for the next generation of Space Weather predictive tools that is both efficient and accurate. The aim of the new approach is to provide interplanetary space weather forecasting models with accurate time dependent boundary conditions of erupting magnetic flux ropes in the upper solar corona. Methods. To produce boundary conditions, we couple two different modelling techniques, MHD simulations and a quasi-static non-potential evolution model. Both are applied on a spatial domain that covers the entire solar surface, although they extend over a different radial distance. The non-potential model uses a time series of observed synoptic magnetograms to drive the non-potential quasi-static evolution of the coronal magnetic field. This allows us to follow the formation and loss of equilibrium of magnetic flux ropes. Following this a MHD simulation captures the dynamic evolution of the erupting flux rope, when it is ejected into interplanetary space. Results.The present paper focuses on the MHD simulations that follow the ejection of magnetic flux ropes to 4 R⊙. We first propose a technique for specifying the pre-eruptive plasma properties in the corona. Next, time dependent MHD simulations describe the ejection of two magnetic flux ropes, that produce time dependent boundary conditions for the magnetic field and plasma at 4 R⊙ that in future may be applied to interplanetary space weather prediction models. Conclusions. In the present paper, we show that the dual use of quasi-static non-potential magnetic field simulations and full time dependent MHD simulations can produce realistic inhomogeneous boundary conditions for space weather forecasting tools. Before a fully operational model can be produced there are a number of technical and scientific challenges that still need to be addressed. Nevertheless, we illustrate that coupling quasi-static and MHD simulations in this way can significantly reduce the computational time required to produce realistic space weather boundary conditions.

scholarly journals Multi-Spacecraft Observations of a Unique Type of High-Latitude ICME

2021 ◽  
Author(s):  
Megan Maunder ◽  
Claire Foullon ◽  
Robert Forsyth ◽  
Emma Davies ◽  
David Barnes ◽  
...  
Keyword(s):  
Space Weather ◽  
High Latitude ◽  
High Speed ◽  
Weather Forecasting ◽  
Flux Rope ◽  
High Latitudes ◽  
Unique Type ◽  
Sheath Region ◽  
Solar Winds ◽  
Spacecraft Data

<p>Coronal Mass Ejections (CMEs) and their interplanetary counterparts (ICMEs) are key drivers of space weather throughout the heliosphere. Observational studies are used to understand their evolution and for developing existing models and theory in space weather forecasting. Motivated by the future exploration of the solar high-latitudes by Solar Orbiter and complimented by Parker Solar Probe, we aim to contribute to the understanding of high-latitude CMEs as they develop into ICMEs. We examine a high-latitude CME and its subsequent ICME using data from STEREO, Ulysses, and near-Earth spacecraft. We apply a triangulation method to the remote-sensing images from the twin STEREO spacecraft and conduct a multi-spacecraft analysis using the in-situ Ulysses, STEREO, and near-Earth spacecraft data. The Ulysses observations, supported by the other spacecraft, provides a clear picture of the ICME geometry and structure: a shock, followed by a sheath region, and a magnetic flux rope followed by a high-speed stream. This ICME differs from the known ‘over-expanding’ types observed in the high-latitudes by the Ulysses mission, in that it straddles a region between the slow and fast solar winds which in itself drives a shock.</p>

scholarly journals Estimating the Magnetic Structure of an Erupting CME Flux Rope From AR12158 Using Data-Driven Modeling

2021 ◽  
Vol 8 ◽  
Author(s):  
Emilia K. J. Kilpua ◽  
Jens Pomoell ◽  
Daniel Price ◽  
Ranadeep Sarkar ◽  
Eleanna Asvestari
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Magnetic Flux ◽  
Large Scale ◽  
Weather Forecasting ◽  
Interplanetary Space ◽  
Lower Boundary ◽  
Flux Rope ◽  
Data Driven ◽  
Lower Boundary Condition

We investigate here the magnetic properties of a large-scale magnetic flux rope related to a coronal mass ejection (CME) that erupted from the Sun on September 12, 2014 and produced a well-defined flux rope in interplanetary space on September 14–15, 2014. We apply a fully data-driven and time-dependent magnetofrictional method (TMFM) using Solar Dynamics Observatory (SDO) magnetograms as the lower boundary condition. The simulation self-consistently produces a coherent flux rope and its ejection from the simulation domain. This paper describes the identification of the flux rope from the simulation data and defining its key parameters (e.g., twist and magnetic flux). We define the axial magnetic flux of the flux rope and the magnetic field time series from at the apex and at different distances from the apex of the flux rope. Our analysis shows that TMFM yields axial magnetic flux values that are in agreement with several observational proxies. The extracted magnetic field time series do not match well with in-situ components in direct comparison presumably due to interplanetary evolution and northward propagation of the CME. The study emphasizes also that magnetic field time-series are strongly dependent on how the flux rope is intercepted which presents a challenge for space weather forecasting.

scholarly journals Space weather: the solar perspective

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Manuela Temmer
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Weather Forecasting ◽  
Interplanetary Space ◽  
Three Dimensions ◽  
Space Weather Forecasting ◽  
Stereo Mission ◽  
Interaction Regions ◽  
Near Future ◽  
First Time

AbstractThe Sun, as an active star, is the driver of energetic phenomena that structure interplanetary space and affect planetary atmospheres. The effects of Space Weather on Earth and the solar system is of increasing importance as human spaceflight is preparing for lunar and Mars missions. This review is focusing on the solar perspective of the Space Weather relevant phenomena, coronal mass ejections (CMEs), flares, solar energetic particles (SEPs), and solar wind stream interaction regions (SIR). With the advent of the STEREO mission (launched in 2006), literally, new perspectives were provided that enabled for the first time to study coronal structures and the evolution of activity phenomena in three dimensions. New imaging capabilities, covering the entire Sun-Earth distance range, allowed to seamlessly connect CMEs and their interplanetary counterparts measured in-situ (so called ICMEs). This vastly increased our knowledge and understanding of the dynamics of interplanetary space due to solar activity and fostered the development of Space Weather forecasting models. Moreover, we are facing challenging times gathering new data from two extraordinary missions, NASA’s Parker Solar Probe (launched in 2018) and ESA’s Solar Orbiter (launched in 2020), that will in the near future provide more detailed insight into the solar wind evolution and image CMEs from view points never approached before. The current review builds upon the Living Reviews article by Schwenn from 2006, updating on the Space Weather relevant CME-flare-SEP phenomena from the solar perspective, as observed from multiple viewpoints and their concomitant solar surface signatures.

scholarly journals Configuration of a Magnetic Cloud From Solar Orbiter and Wind Spacecraft In-situ Measurements

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiang Hu ◽  
Wen He ◽  
Lingling Zhao ◽  
Edward Lu
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Flux Rope ◽  
3D Models ◽  
Field Configuration ◽  
Magnetic Clouds ◽  
Physical Parameters ◽  
The Sun ◽  
Wind Spacecraft

Coronal mass ejections (CMEs) represent one type of the major eruption from the Sun. Their interplanetary counterparts, the interplanetary CMEs (ICMEs), are the direct manifestations of these structures when they propagate into the heliosphere and encounter one or more observing spacecraft. The ICMEs generally exhibit a set of distinctive signatures from the in-situ spacecraft measurements. A particular subset of ICMEs, the so-called Magnetic Clouds (MCs), is more uniquely defined and has been studied for decades, based on in-situ magnetic field and plasma measurements. By utilizing the latest multiple spacecraft measurements and analysis tools, we report a detailed study of the internal magnetic field configuration of an MC event observed by both the Solar Orbiter (SO) and Wind spacecraft in the solar wind near the Sun-Earth line. Both two-dimensional (2D) and three-dimensional (3D) models are applied to reveal the flux rope configurations of the MC. Various geometrical as well as physical parameters are derived and found to be similar within error estimates for the two methods. These results quantitatively characterize the coherent MC flux rope structure crossed by the two spacecraft along different paths. The implication for the radial evolution of this MC event is also discussed.

scholarly journals An integrated data-driven solar wind - CME numerical framework for space weather forecasting

2020 ◽  
Author(s):  
Nishant M. Narechania ◽  
Ljubomir Nikolic ◽  
Lucie Freret ◽  
Hans De Sterck ◽  
Clinton P. T. Groth
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Space Weather ◽  
Weather Forecasting ◽  
Coronal Magnetic Field ◽  
Data Driven ◽  
Source Surface ◽  
Field Source ◽  
Space Weather Forecasting ◽  
Semi Empirical

The development of numerical models and tools which have operational space weather potential is an increasingly important area of research. This study presents recent Canadian efforts toward the development of a numerical framework for Sun-to-Earth simulations of solar wind disturbances. This modular three-dimensional (3D) simulation framework is based on a semi-empirical data-driven approach to describe the solar corona and an MHD-based description of the heliosphere. In the present configuration, the semi-empirical component uses the Potential Field Source Surface (PFSS) and Schatten Current Sheet (SCS) models to derive the coronal magnetic field based on observed magnetogram data. Using empirical relations, solar wind properties are associated with this coronal magnetic field. Together with a Coronal Mass Ejection (CME) model, this provides inner boundary conditions for a global MHD model which is used to describe interplanetary propagation of the solar wind and CMEs. The proposed MHD numerical approach makes use of advanced numerical techniques. The 3D MHD code employs a finite-volume discretization procedure with limited piecewise linear reconstruction to solve the governing partial-differential equations. The equations are solved on a body-fitted hexahedral multi-block cubed-sphere mesh and an efficient iterative Newton method is used for time-invariant simulations and an explicit time-marching scheme is applied for unsteady cases. Additionally, an efficient anisotropic block-based refinement technique provides significant reductions in the size of the computational mesh by locally refining the grid in selected directions as dictated by the flow physics. The capabilities of the framework for accurately capturing solar wind structures and forecasting solar wind properties at Earth are demonstrated. Furthermore, a comparison with previously reported results and future space weather forecasting challenges are discussed.

scholarly journals A distinct magnetic property of the inner penumbral boundary

2020 ◽  
Vol 638 ◽  
pp. A28 ◽  
Author(s):  
Jan Jurčák ◽  
Markus Schmassmann ◽  
Matthias Rempel ◽  
Nazaret Bello González ◽  
Rolf Schlichenmaier
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Potential Field ◽  
Magnetic Energy ◽  
Vertical Component ◽  
Flux Rope ◽  
Field Configuration ◽  
The Magnetic Field ◽  
Upper Boundary

Context. Analyses of sunspot observations revealed a fundamental magnetic property of the umbral boundary: the invariance of the vertical component of the magnetic field. Aims. We analyse the magnetic properties of the umbra-penumbra boundary in simulated sunspots and thus assess their similarity to observed sunspots. We also aim to investigate the role of the plasma β and the ratio of kinetic to magnetic energy in simulated sunspots in the convective motions because these quantities cannot be reliably determined from observations. Methods. We used a set of non-gray simulation runs of sunspots with the MURaM code. The setups differed in terms of subsurface magnetic field structure and magnetic field boundary imposed at the top of the simulation domain. These data were used to synthesize the Stokes profiles, which were then degraded to the Hinode spectropolarimeter-like observations. Then, the data were treated like real Hinode observations of a sunspot, and magnetic properties at the umbral boundaries were determined. Results. Simulations with potential field extrapolation produce a realistic magnetic field configuration on the umbral boundaries of the sunspots. Two simulations with a potential field upper boundary, but different subsurface magnetic field structures, differ significantly in the extent of their penumbrae. Increasing the penumbra width by forcing more horizontal magnetic fields at the upper boundary results in magnetic properties that are not consistent with observations. This implies that the size of the penumbra is given by the subsurface structure of the magnetic field, that is, by the depth and inclination of the magnetopause, which is shaped by the expansion of the sunspot flux rope with height. None of the sunspot simulations is consistent with the observed properties of the magnetic field and the direction of the Evershed flow at the same time. Strong outward-directed Evershed flows are only found in setups with an artificially enhanced horizontal component of the magnetic field at the top boundary that are not consistent with the observed magnetic field properties at the umbra-penumbra boundary. We stress that the photospheric boundary of simulated sunspots is defined by a magnetic field strength of equipartition field value.

scholarly journals Magnetic clouds seen at different locations in the heliosphere

2008 ◽  
Vol 26 (2) ◽  
pp. 213-229 ◽  
Author(s):  
L. Rodriguez ◽  
A. N. Zhukov ◽  
S. Dasso ◽  
C. H. Mandrini ◽  
H. Cremades ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Space ◽  
Field Configuration ◽  
Magnetic Clouds ◽  
Magnetic Characteristics ◽  
The Sun ◽  
Source Regions ◽  
Plasma Species ◽  
In Situ Observations

Abstract. We analyze two magnetic clouds (MCs) observed in different points of the heliosphere. The main aim of the present study is to provide a link between the different aspects of this phenomenon, starting with information on the origins of the MCs at the Sun and following by the analysis of in-situ observations at 1 AU and at Ulysses. The candidate source regions were identified in SOHO/EIT and SOHO/MDI observations. They were correlated with H-α images that were obtained from ground-based observatories. Hints on the internal magnetic field configuration of the associated coronal mass ejections are obtained from LASCO C2 images. In interplanetary space, magnetic and plasma moments of the distribution function of plasma species (ACE/Ulysses) were analyzed together with information on the plasma composition, and the results were compared between both spacecraft in order to understand how these structures interact and evolve in their cruise from the Sun to 5 AU. Additionally, estimates of global magnitudes of magnetic fluxes and helicity were obtained from magnetic field models applied to the data in interplanetary space. We have found that these magnetic characteristics were well kept from their solar source, up to 5 AU where Ulysses provided valuable information which, together with that obtained from ACE, can help to reinforce the correct matching of solar events and their interplanetary counterparts.

scholarly journals Formation of a tiny flux rope in the center of an active region driven by magnetic flux emergence, convergence, and cancellation

2020 ◽  
Vol 642 ◽  
pp. A199
Author(s):  
Ruisheng Zheng ◽  
Yao Chen ◽  
Bing Wang ◽  
Hongqiang Song ◽  
Wenda Cao
Keyword(s):  
Active Region ◽  
Magnetic Flux ◽  
Space Weather ◽  
Source Region ◽  
Flux Rope ◽  
Negative Polarity ◽  
Flux Emergence ◽  
High Quality ◽  
Solar Eruptions ◽  
A Minor

Aims. Flux ropes are generally believed to be core structures of solar eruptions that are significant for the space weather, but their formation mechanism remains intensely debated. We report on the formation of a tiny flux rope beneath clusters of active region loops on 2018 August 24. Methods. Combining the high-quality multiwavelength observations from multiple instruments, we studied the event in detail in the photosphere, chromosphere, and corona. Results. In the source region, the continual emergence of two positive polarities (P1 and P2) that appeared as two pores (A and B) is unambiguous. Interestingly, P2 and Pore B slowly approached P1 and Pore A, implying a magnetic flux convergence. During the emergence and convergence, P1 and P2 successively interacted with a minor negative polarity (N3) that emerged, which led to a continuous magnetic flux cancellation. As a result, the overlying loops became much sheared and finally evolved into a tiny twisted flux rope that was evidenced by a transient inverse S-shaped sigmoid, the twisted filament threads with blueshift and redshift signatures, and a hot channel. Conclusions. All the results show that the formation of the tiny flux rope in the center of the active region was closely associated with the continuous magnetic flux emergence, convergence, and cancellation in the photosphere. Hence, we suggest that the magnetic flux emergence, convergence, and cancellation are crucial for the formation of the tiny flux rope.

Comparative study of halo CME arrival predictions

2021 ◽  
Author(s):  
Emiliya Yordanova ◽  
Mateja Dumbovic ◽  
Manuela Temmer ◽  
Camilla Scolini ◽  
Jasmina Magdalenic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Situational Awareness ◽  
Weather Forecasting ◽  
Geomagnetic Storms ◽  
Interplanetary Space ◽  
Accurate Estimation ◽  
Arrival Times ◽  
Space Weather Forecasting ◽  
Halo Cmes ◽  
Speed Prediction

<p>Halo coronal mass ejections (CMEs) are one of the most effective drivers of intense geomagnetic storms. Despite the recent advances in space weather forecasting, the accurate arrival prediction of halo CMEs remains a challenge.  This is because in general CMEs interact with the background solar wind during their propagation in the interplanetary space. In addition, in the case of halo CMEs, the accurate estimation of their kinematics is difficult due to projection effects in the plane-of-sky.</p><p>In this study, we are revisiting the arrival of twelve geoeffective Earth-directed fast halo CMEs using an empirical and a numerical approaches. For this purpose we refine the input to the Drag-based Model (DBM) and to the EUropean Heliospheric Forecasting Information Asset (EUHFORIA), which are recently available for users from the ESA Space Situational Awareness Portal (http://swe.ssa.esa.int).</p><p>The DBM model has been tested using different values for the input drag parameter.  On average, the predicted arrival times are confined in the range of ± 10 h. The closest arrival to the observed one has been achieved with a drag value higher than the recommended for fast CMEs. Setting a higher drag also helped to obtain a closer to the observed CME arrival speed prediction. These results suggest that the exerted solar wind drag was higher than expected. Further, we are searching for clues about the CME propagation by performing EUHFORIA runs using the same CME kinematics. Preliminary results show that both models perform poorly for CMEs that have possibly undergone CME-CME interaction, underlying again the importance of taking into account the state of the interplanetary space in the CME forecast.</p>

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