Three-dimensional (3-d) magnetohydrodynamics (MHD) modeling is a key method for studying the interplanetary solar wind. In this article, In this paper, we introduce a new 3-d MHD solar wind model driven by the self-consistent boundary condition obtained from multiple observations and Artificial Neural Network (ANN) machine learning technique. At the inner boundary, the magnetic field is derived using the magnetogram and potential field source surface extrapolation; the electron density is derived from the polarized brightness (pB) observations, the velocity can be deduced by an ANN using both the magnetogram and pB observations, and the temperature is derived from the magnetic field and electron density by a self-consistent method. Then, the 3-d interplanetary solar wind from CR2057 to CR2062 are modeled by the new model with the self-consistent boundary conditions. The modeling results present various observational characteristics at different latitudes, and are in good agreement with both the OMNI and Ulysses observations.

How to cite: Shen, F., Yang, Y., and Feng, X.: 3D MHD Modeling of Interplanetary Solar Wind Using Self-Consistent Boundary Condition Obtained from Multiple Observations and Machine Learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10143, https://doi.org/10.5194/egusphere-egu23-10143, 2023.

Spectroscopic observations of the solar atmosphere reveal regions of the solar corona that are enriched in the abundance of heavy element with low-first ionisation potential (examples of low ‘FIP’ i.e. with <10 eV are Fe, Mg) relative to photospheric abundances. This enhancement in the abundance of low-FIP elements by a factor of three or four, called the ‘FIP effect’, is still not well understood. Moreover enriched abundances of low-FIP elements are also observed in the slow solar wind, which could give us more insights on its origins. An inverse-FIP effect corresponding to a decreased abundance of low-FIP elements has been measured in the atmosphere of M-type stars.

Turbulent mixing of the chromosphere combined with the ponderomotive force caused by Alfvén waves propagating in these atmosphere could give a mechanism that might explain the FIP effect. Diffusive theories including the thermal force exerted on the ions due to a collision frequency gradient has also a role to play on minor ion extraction from the chromosphere.  Our goal is to study and compare these effects using  ISAM, a new 1D 16 moments multi-fluid model taking into account collisional effects of the different heavy ions. In this work we use profiles from 3 different solar wind types simulated using ISAM in which we propagate Alfvén waves with a Shell Model of Alfvén-wave turbulence. We then compare the FIP bias obtained from these 3 types of wind.

This work has been funded by the ERC SLOWS SOURCE − DLV − 819189

How to cite: Lomazzi, P., Réville, V., Rouillard, A., and Petit, P.: Studying ionic composition in open field regions using a 16 moments multi-species fluid model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7415, https://doi.org/10.5194/egusphere-egu23-7415, 2023.

Solar radio zebras detected as fine structures of Type IV radio bursts help to diagnose the coronal plasma at kinetic micro-scales. One of the models of the radio zebras is the electron-cyclotron maser instability based on a double plasma resonance at gyro-harmonics of the electron cyclotron frequency when ω_pe > ω_ce. Though the gyro-harmonic numbers estimated for zebra observations are very high, in some cases exceeding 100, it is still uncertain how the instability can grow and generate zebra stripes for them. To investigate the instability evolution, we studied its growth and saturation by utilizing analytical calculations and particle-in-cell simulations. We found that the growth rates and saturation energies as functions of the cyclotron-to-plasma frequency ratio form a profile that peaks approximately at the integer harmonics of the cyclotron frequency. Nonetheless, the peaks shift to lower frequencies with increasing the plasma loss-cone temperature, and they broaden and decrease with increasing the gyro-harmonic number. These results suggest that emissions for very high gyro-harmonic numbers should not be formed. Hence, to explain the detected high gyro-harmonic numbers of one hundred, we also investigated the growth rates as a function of the loss-cone angle and found that distributions with very  high loss-cone angles can interpret the observations. We proposed that such large loss-cone angles can be generated in magnetic loops with small magnetic field gradients or below an X-point of the magnetic reconnection. 

How to cite: Benáček, J. and Karlický, M.: Electron-cyclotron emission model of solar radio zebras with high gyro-harmonic numbers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17380, https://doi.org/10.5194/egusphere-egu23-17380, 2023.

According to the standard scenario of plasma emission, the escaping radiations are generated from the nonlinear development of the kinetic bump-on-tail instability, by a single beam of energetic electrons interacting with an overdense plasma. The primarily-excited beam-Langmuir mode and its further scattering over ion-related disturbances are suggested to be critical to the radiation process. Yet, non-beam distributions of energetic electrons, such as the ring (or ring-beam), DGH, loss-cone, horseshoe-like, etc., also exist broadly in space and astrophysical plasmas. They may drive wave modes distinct from those in the beam-plasma system. The corresponding radiation process could be distinct from that described by the standard scenario. To clarify this, we conducted particle-in-cell simulations to investigate the nonlinear response of an overdense plasma disturbed by energetic electrons of velocity distributions (VDs) changing from beam-like to ring-like. Efficient excitations of both the fundamental (F) and harmonic (H) plasma emissions are found for all the VDs investigated here, yet the kinetic instability, the wave modes excited, and the F/H radiation process are different. Details of these differences will be overviewed in this report.

How to cite: Chen, Y.: Coherent Radiation in Overdense Plasmas Interacting with Energetic Electrons of Different Velocity Distributions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17301, https://doi.org/10.5194/egusphere-egu23-17301, 2023.

Resolving thermodynamic transport in three-dimensional models of stratified coronal loops is a long-standing challenge that limits progress in solving the coronal heating problem.
Since three-dimensional thermal conduction in MHD has been computationally too expensive to resolve the steep temperature gradients in the transition region, two simpler approaches have been adopted: one-dimensional, field-aligned models following the thermal response to imposed forms of heating, and three-dimensional MHD models that produce the forms of Ohmic and viscous heating self-consistently but cannot consider the consequent thermodynamic response.
Now, using a novel numerical technique, TRAC, we can resolve energetic transport in the transition region in fully three-dimensional MHD models.
In a model of a multi-stranded coronal loop in a curved arcade, we investigate the heating produced in an 'avalanche'-like process.
In such, a chain reaction of reconnection-induced local events occurs, with each event disturbing wider plasma and triggering other processes, such as shocks, jets, and turbulence, that generate heating, which we analyse with particular attention to the spatio-temporal distribution of nanoflares.
At the same time, we treat the thermodynamic response of the plasma self-consistently, and study the evolving temperature profiles.
Avalanches successfully propagate in curved arcades and appear capable of maintaining a hot corona with realistic temperatures and densities in heated loops.
One novelty of interest lies in `campfire'-like events, with simultaneous reconnection events at disjoint sites along coronal strands, akin to recent results from Solar Orbiter.

How to cite: Reid, J., Johnston, C. D., Threlfall, J., and Hood, A. W.: Self-consistent modelling of nanoflares: generation of heating and thermodynamic response in 3D MHD, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3475, https://doi.org/10.5194/egusphere-egu23-3475, 2023.

We perform a data-constrained simulation with the zero-β assumption to study the mechanisms of strong rotation and failed eruption of a filament in active region 11474 on 2012 May 5 observed by Solar Dynamics Observatory and Solar Terrestrial Relations Observatory. The initial magnetic field is provided by nonlinear force-free field extrapolation, which is reconstructed by the regularized Biot-Savart laws and magnetofrictional method. Our simulation reproduces most observational features very well, e.g., the filament large-angle rotation of about 130°, the confined eruption and the flare ribbons, allowing us to analyze the underlying physical processes behind observations. We discover two flux ropes in the sigmoid system, an upper flux rope (MFR1) and a lower flux rope (MFR2), which correspond to the filament and hot channel in observations, respectively. Both flux ropes undergo confined eruptions. MFR2 grows by tether-cutting reconnection during the eruption. The rotation of MFR1 is related to the shear-field component along the axis. Moreover, we find that the magnetic tension force is the cause of the confined eruption of MFR1. We also suggest that the mutual interaction between MFR1 and MFR2 contributes to the large-angle rotation and the eruption failure. In addition, we calculate the temporal evolution of the twist and writhe of MFR1, which may be a hint of probably existing reversal rotation.

How to cite: Zhang, X., Guo, J., Guo, Y., Ding, M., and Keppens, R.: Rotation and Confined Eruption of a Double Flux-Rope System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10557, https://doi.org/10.5194/egusphere-egu23-10557, 2023.

A collisionless shock is a self-organized system, the main task of which is fast and stable transfer of the conserved quantities, that is, mass, momentum, and energy, from one side, upstream, to the other side, downstream, while adding entropy. ”Fast” means that the transfer occurs at the scales
much smaller than the MHD scales. ”Stable” means that there are not disruptions of substantial changes on average, except those which are caused
by variations of ambient conditions. In this approach the developing shock structure is the one which ensures this transfer. This means, that if the
transfer stability is not possible without an overshoot, an overshoot has to be formed. If it is not possible without rippling, rippling will develop. Since
ions are the main carriers of these conserved quantities, it is ions which are responsible for developing the structure and it is ions which have to
most strongly affected by it. In particular, we show that overshoot plays an important role regulating ion reflection so that the shock becomes stable.

How to cite: Gedalin, M.: Collisionless shock as a self-organized system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17375, https://doi.org/10.5194/egusphere-egu23-17375, 2023.