scholarly journals CME–HSS Interaction and Characteristics Tracked from Sun to Earth

Solar Physics ◽  
2019 ◽  
Vol 294 (9) ◽  
Author(s):  
Stephan G. Heinemann ◽  
Manuela Temmer ◽  
Charles J. Farrugia ◽  
Karin Dissauer ◽  
Christina Kay ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Free Field ◽  
Field Configuration ◽  
Solar Dynamics Observatory ◽  
Magnetic Field Configuration ◽  
Launch Site ◽  
Nonlinear Force ◽  
Solar Dynamics

Abstract In a thorough study, we investigate the origin of a remarkable plasma and magnetic field configuration observed in situ on June 22, 2011, near L1, which appears to be a magnetic ejecta (ME) and a shock signature engulfed by a solar wind high-speed stream (HSS). We identify the signatures as an Earth-directed coronal mass ejection (CME), associated with a C7.7 flare on June 21, 2011, and its interaction with a HSS, which emanates from a coronal hole (CH) close to the launch site of the CME. The results indicate that the major interaction between the CME and the HSS starts at a height of $1.3~\mbox{R}_{\odot }$ 1.3 R ⊙ up to $3~\mbox{R}_{\odot }$ 3 R ⊙ . Over that distance range, the CME undergoes a strong north-eastward deflection of at least $30^{\circ }$ 30 ∘ due to the open magnetic field configuration of the CH. We perform a comprehensive analysis for the CME–HSS event using multi-viewpoint data (from the Solar TErrestrial RElations Observatories, the Solar and Heliospheric Observatory and the Solar Dynamics Observatory), and combined modeling efforts (nonlinear force-free field modeling, Graduated Cylindrical Shell CME modeling, and the Forecasting a CME’s Altered Trajectory – ForeCAT model). We aim at better understanding its early evolution and interaction process as well as its interplanetary propagation and related in situ signatures, and finally the resulting impact on the Earth’s magnetosphere.

scholarly journals Statistical Analysis and Catalog of Non-polar Coronal Holes Covering the SDO-Era Using CATCH

Solar Physics ◽  
2019 ◽  
Vol 294 (10) ◽  
Author(s):  
Stephan G. Heinemann ◽  
Manuela Temmer ◽  
Niko Heinemann ◽  
Karin Dissauer ◽  
Evangelia Samara ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Coronal Hole ◽  
High Speed ◽  
Extreme Ultraviolet ◽  
Coronal Holes ◽  
Central Meridian ◽  
Solar Dynamics Observatory ◽  
Speed Solar Wind ◽  
Solar Dynamics ◽  
Hole Boundary

Abstract Coronal holes are usually defined as dark structures seen in the extreme ultraviolet and X-ray spectrum which are generally associated with open magnetic fields. Deriving reliably the coronal hole boundary is of high interest, as its area, underlying magnetic field, and other properties give important hints as regards high speed solar wind acceleration processes and compression regions arriving at Earth. In this study we present a new threshold-based extraction method, which incorporates the intensity gradient along the coronal hole boundary, which is implemented as a user-friendly SSW-IDL GUI. The Collection of Analysis Tools for Coronal Holes (CATCH) enables the user to download data, perform guided coronal hole extraction and analyze the underlying photospheric magnetic field. We use CATCH to analyze non-polar coronal holes during the SDO-era, based on 193 Å filtergrams taken by the Atmospheric Imaging Assembly (AIA) and magnetograms taken by the Heliospheric and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO). Between 2010 and 2019 we investigate 707 coronal holes that are located close to the central meridian. We find coronal holes distributed across latitudes of about ${\pm}\, 60^{\circ}$±60∘, for which we derive sizes between $1.6 \times 10^{9}$1.6×109 and $1.8 \times 10^{11}\mbox{ km}^{2}$1.8×1011 km2. The absolute value of the mean signed magnetic field strength tends towards an average of $2.9\pm 1.9$2.9±1.9 G. As far as the abundance and size of coronal holes is concerned, we find no distinct trend towards the northern or southern hemisphere. We find that variations in local and global conditions may significantly change the threshold needed for reliable coronal hole extraction and thus, we can highlight the importance of individually assessing and extracting coronal holes.

scholarly journals Radiation belt data assimilation of a moderate storm event using a magnetic field configuration from the physics-based RAM-SCB model

2014 ◽  
Vol 32 (5) ◽  
pp. 473-483 ◽  
Author(s):  
Y. Yu ◽  
J. Koller ◽  
V. K. Jordanova ◽  
S. G. Zaharia ◽  
H. C. Godinez
Keyword(s):  
Magnetic Field ◽  
Data Assimilation ◽  
Radiation Belt ◽  
Field Model ◽  
Field Configuration ◽  
Storm Event ◽  
Magnetic Field Configuration ◽  
Magnetic Field Model ◽  
Global Magnetic Field

Abstract. Data assimilation using Kalman filters provides an effective way of understanding both spatial and temporal variations in the outer electron radiation belt. Data assimilation is the combination of in situ observations and physical models, using appropriate error statistics to approximate the uncertainties in both the data and the model. The global magnetic field configuration is one essential element in determining the adiabatic invariants for the phase space density (PSD) data used for the radiation belt data assimilation. The lack of a suitable global magnetic field model with high accuracy is still a long-lasting problem. This paper employs a physics-based magnetic field configuration for the first time in a radiation belt data assimilation study for a moderate storm event on 19 December 2002. The magnetic field used in our study is the magnetically self-consistent inner magnetosphere model RAM-SCB, developed at Los Alamos National Laboratory (LANL). Furthermore, we apply a cubic spline interpolation method in converting the differential flux measurements within the energy spectrum, to obtain a more accurate PSD input for the data assimilation than the commonly used linear interpolation approach. Finally, the assimilation is done using an ensemble Kalman filter (EnKF), with a localized adaptive inflation (LAI) technique to appropriately account for model errors in the assimilation and improve the performance of the Kalman filter. The assimilative results are compared with results from another assimilation experiment using the Tsyganenko 2001S (T01S) magnetic field model, to examine the dependence on a magnetic field model. Results indicate that the data assimilations using different magnetic field models capture similar features in the radiation belt dynamics, including the temporal evolution of the electron PSD during a storm and the location of the PSD peak. The assimilated solution predicts the energy differential flux to a relatively good degree when compared with independent LANL-GEO in situ observations. A closer examination suggests that for the chosen storm event, the assimilation using the RAM-SCB predicts a better flux at most energy levels during storm recovery phase but is slightly worse in the storm main phase than the assimilation using the T01S model.

scholarly journals Simulating the Coronal Evolution of Bipolar Active Regions to Investigate the Formation of Flux Ropes

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
S. L. Yardley ◽  
D. H. Mackay ◽  
L. M. Green
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Initial Conditions ◽  
Free Field ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Solar Dynamics Observatory ◽  
Horizontal Magnetic Field ◽  
Nonlinear Force ◽  
Force Free Field

AbstractThe coronal magnetic field evolution of 20 bipolar active regions (ARs) is simulated from their emergence to decay using the time-dependent nonlinear force-free field method of Mackay, Green, and van Ballegooijen (Astrophys. J. 729, 97, 2011). A time sequence of cleaned photospheric line-of-sight magnetograms, which covers the entire evolution of each AR, is used to drive the simulation. A comparison of the simulated coronal magnetic field with the 171 and 193 Å observations obtained by the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), is made for each AR by manual inspection. The results show that it is possible to reproduce the evolution of the main coronal features such as small- and large-scale coronal loops, filaments and sheared structures for 80% of the ARs. Varying the boundary and initial conditions, along with the addition of physical effects such as Ohmic diffusion, hyperdiffusion and a horizontal magnetic field injection at the photosphere, improves the match between the observations and simulated coronal evolution by 20%. The simulations were able to reproduce the build-up to eruption for 50% of the observed eruptions associated with the ARs. The mean unsigned time difference between the eruptions occurring in the observations compared to the time of eruption onset in the simulations was found to be ≈5 hrs. The simulations were particularly successful in capturing the build-up to eruption for all four eruptions that originated from the internal polarity inversion line of the ARs. The technique was less successful in reproducing the onset of eruptions that originated from the periphery of ARs and large-scale coronal structures. For these cases global, rather than local, nonlinear force-free field models must be used. While the technique has shown some success, eruptions that occur in quick succession are difficult to reproduce by this method and future iterations of the model need to address this.

scholarly journals External reconnection and resultant reconfiguration of overlying magnetic fields during sympathetic eruptions of two filaments

2020 ◽  
Vol 640 ◽  
pp. A101 ◽  
Author(s):  
Y. J. Hou ◽  
T. Li ◽  
Z. P. Song ◽  
J. Zhang
Keyword(s):  
Free Field ◽  
Physical Nature ◽  
Null Point ◽  
Solar Dynamics Observatory ◽  
The South ◽  
Density Reduction ◽  
Narrow Region ◽  
Combining Data ◽  
Nonlinear Force ◽  
Solar Dynamics

Context. Sympathetic eruptions of two solar filaments have been studied for several decades, but the detailed physical process through which one erupting filament triggers another is still under debate. Aims. Here we aim to investigate the physical nature of a sympathetic event involving successive eruptions of two filaments on 2015 November 15-16, which presented abundant sympathetic characteristics. Methods. Combining data from the Solar Dynamics Observatory and other observatories as well as results of nonlinear force-free field (NLFFF) extrapolations, we study the evolution of observational features and magnetic topology during the sympathetic event. Results. The two filaments (north F1 and south F2) were separated by a narrow region of negative polarity, and F1 first erupted, producing a two-ribbon flare. When the outward-spreading ribbon produced by F1 approached stable F2, a weak brightening was observed to the south of F2 and then spread northward, inward approaching F2. Behind this inward-spreading brightening, a dimming region characterized by a plasma density reduction of 30% was extending. NLFFF extrapolations with a time sequence reveal that fields above pre-eruption F1 and F2 constituted a quadrupolar magnetic system with a possible null point. Moreover, the null point kept moving toward F2 and descending within the following hours. We infer that the rising F1 pushed its overlying fields toward the fields above stable F2 and caused successive external reconnection between the overlying fields. From outside to inside (lower and lower in height), the fields above pre-eruption F2 were gradually involved in the reconnection, manifesting as the inward-spreading brightening and extending dimming on the south side of F2. Furthermore, the external reconnection could reconfigure the overlying fields of F2 by transporting magnetic flux from its west part to the east part, which is further verified by the subsequent partial eruption of F2. Conclusions. We propose an integrated evidence chain to demonstrate the critical roles of external magnetic reconnection and the resultant reconfiguration of overlying fields on the sympathetic eruptions of two filaments.

scholarly journals Sunspot penumbral filaments intruding into a light bridge and the resultant reconnection jets

2020 ◽  
Vol 642 ◽  
pp. A44
Author(s):  
Y. J. Hou ◽  
T. Li ◽  
S. H. Zhong ◽  
S. H. Yang ◽  
Y. L. Guo ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Magnetic Reconnection ◽  
Free Field ◽  
Convincing Evidence ◽  
Solar Dynamics Observatory ◽  
Combining Data ◽  
West Part ◽  
Nonlinear Force ◽  
Penumbral Filament ◽  
Solar Dynamics

Context. Penumbral filaments and light bridges are prominent structures inside sunspots and are important for understanding the nature of sunspot magnetic fields and magneto-convection underneath. Aims. We investigate an interesting event where several penumbral filaments intrude into a sunspot light bridge. In doing so we aim to gain further insight into the magnetic fields of the sunspot penumbral filament and light bridge, as well as their interaction. Methods. Combining data from the New Vacuum Solar Telescope, Solar Dynamics Observatory, and Interface Region Imaging Spectrograph, we study the emission, kinematic, and magnetic topology characteristics of the penumbral filaments intruding into the light bridge and the resultant jets. Results. At the west part of the light bridge, the intruding penumbral filaments penetrate into the umbrae on both sides of the light bridge, and two groups of jets are also detected. The jets share the same projected morphology with the intruding filaments and are accompanied by intermittent footpoint brightenings. Simultaneous spectral imaging observations provide convincing evidence for the presences of magnetic-reconnection-related heating and bidirectional flows near the jet bases and contribute to measuring the vector velocities of the jets. Additionally, nonlinear force-free field extrapolation results reveal strong and highly inclined magnetic fields along the intruding penumbral filaments, highly consistent with the results deduced from the vector velocities of the jets. Therefore, we propose that the jets could be caused by magnetic reconnections between emerging fields within the light bridge and the nearly horizontal fields of intruding filaments. The jets are then ejected outward along the stronger filament fields. Conclusions. Our study indicates that magnetic reconnection could occur between the penumbral filament fields and emerging fields within the light bridge and produce jets along the stronger filament fields. These results further complement the study of magnetic reconnection and dynamic activities within the sunspot.

scholarly journals An Optimization Principle for Computing Stationary MHD Equilibria with Solar Wind Flow

Solar Physics ◽  
2020 ◽  
Vol 295 (10) ◽  
Author(s):  
Thomas Wiegelmann ◽  
Thomas Neukirch ◽  
Dieter H. Nickeler ◽  
Iulia Chifu
Keyword(s):  
Magnetic Field ◽  
Free Field ◽  
Coronal Magnetic Field ◽  
Optimization Method ◽  
Field Configuration ◽  
Optimization Principle ◽  
Mhd Equilibria ◽  
Solar Wind Flow ◽  
Nonlinear Force ◽  
Flow Effects

Abstract In this work we describe a numerical optimization method for computing stationary MHD equilibria. The newly developed code is based on a nonlinear force-free optimization principle. We apply our code to model the solar corona using synoptic vector magnetograms as boundary condition. Below about two solar radii the plasma $\beta $ β and Alfvén Mach number $M_{A}$ M A are small and the magnetic field configuration of stationary MHD is basically identical to a nonlinear force-free field, whereas higher up in the corona (where $\beta $ β and $M_{A}$ M A are above unity) plasma and flow effects become important and stationary MHD and force-free configuration deviate significantly. The new method allows for the reconstruction of the coronal magnetic field further outwards than with potential field, nonlinear force-free or magnetostatic models. This way the model might help to provide the magnetic connectivity for joint observations of remote sensing and in-situ instruments on Solar Orbiter and Parker Solar Probe.

scholarly journals The chromosphere above a δ-sunspot in the presence of fan-shaped jets

2017 ◽  
Vol 609 ◽  
pp. A14 ◽  
Author(s):  
Carolina Robustini ◽  
Jorrit Leenaarts ◽  
Jaime de la Cruz Rodríguez
Keyword(s):  
Magnetic Field ◽  
Velocity Structure ◽  
Atmospheric Temperature ◽  
Field Vector ◽  
Field Configuration ◽  
Atmospheric Conditions ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics ◽  
Temperature Maps ◽  
The Magnetic Field

Context. Delta-sunspots are known to be favourable locations for fast and energetic events like flares and coronal mass ejections. The photosphere of this sunspot type has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not as well known, however. Aims. This study is focused on the chromosphere of a δ-sunspot that harbours a series of fan-shaped jets in its penumbra. The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. Methods. We use data from the Swedish 1m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric Fe i 6302 Å and Ca ii 8542 Å data from the SST using the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature, and velocity structure in the chromosphere. Results. A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from this structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between log τ500 = −2 and log τ500 = −3. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation.

scholarly journals Evolution of Kelvin–Helmholtz Instability in the Fan-spine Topology

2021 ◽  
Vol 923 (1) ◽  
pp. 72
Author(s):  
Sudheer K. Mishra ◽  
Balveer Singh ◽  
A. K. Srivastava ◽  
Pradeep Kayshap ◽  
B. N. Dwivedi
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Rapid Heating ◽  
Field Configuration ◽  
Velocity Shear ◽  
Solar Dynamics Observatory ◽  
Characteristic Wavelength ◽  
Field Lines ◽  
Solar Dynamics ◽  
Shear Motion

Abstract We use multiwavelength imaging observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory to study the evolution of the Kelvin–Helmholtz (K–H) instability in a fan-spine magnetic field configuration. This magnetic topology exists near an active region AR12297 and is rooted in a nearby sunspot. In this magnetic configuration, two layers of cool plasma flow in parallel and interact with each other inside an elongated spine. The slower plasma flow (5 km s−1) is the reflected stream along the spine’s field lines from the top, which interacts with the impulsive plasma upflows (114–144 km s−1) from below. This process generates a shear motion and subsequent evolution of the K–H instability. The amplitude and characteristic wavelength of the K–H unstable vortices increase, satisfying the criterion of the fastest-growing mode of this instability. We also describe how the velocity difference between two layers and the velocity of K–H unstable vortices are greater than the Alfvén speed in the second denser layer, which also satisfies the criterion of the growth of the K–H instability. In the presence of the magnetic field and sheared counterstreaming plasma as observed in the fan-spine topology, we estimate the parametric constant Λ ≥ 1, which confirms the dominance of velocity shear and the evolution of the linear phase of the K–H instability. This observation indicates that in the presence of complex magnetic field structuring and flows, the fan-spine configuration may evolve into rapid heating, while the connectivity changes due to the fragmentation via the K–H instability.

scholarly journals Magnetic field configuration in a flaring active region

2014 ◽  
Vol 10 (S305) ◽  
pp. 97-101 ◽  
Author(s):  
J. Palacios ◽  
L. A. Balmaceda ◽  
L. E. Vieira
Keyword(s):  
Magnetic Field ◽  
Continuous Monitoring ◽  
Field Configuration ◽  
Solar Dynamics Observatory ◽  
Vector Magnetic Field ◽  
Solar Dynamics ◽  
The Magnetic Field ◽  
Class Flare ◽  
High Cadence ◽  
Full Disk

AbstractThe Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) provides continuous monitoring of the Sun's vector magnetic field through full-disk photospheric data with both high cadence and high spatial resolution. Here we investigate the evolution of AR 11249 from March 6 to March 7, 2012. We make use of HMI Stokes imaging, SDO/SHARPs, the HMI magnetic field line-of-sight (LOS) maps and the transverse components of the magnetic field as well as LOS velocity maps in order to detect regions with significant flux emergence and/or cancellation. In addition, we apply the Local Correlation Tracking (LCT) technique to the total and signed magnetic flux data and derive maps of horizontal velocity. From this analysis, we were able to pinpoint localized shear regions (and a shear channel) where penumbrae and pore formation areas, with strong linear polarization signals, are stretched and squeezed, showing also important downflows and upflows. We have also utilized Hinode/SP data and compared them to the HMI-SHARPs and the HMI-Stokes spectrograms. The aforementioned shear channel seems to correspond well with the X-class flare main channel of March 7 2012, as observed in AIA/SDO 171, 304 and 1600 Å.

Sign in / Sign up

Export Citation Format

Share Document