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Zhou, Hongyang ; Turc, Lucile ; Pfau-Kempf, Yann ; [et al.]

Frontiers Media SA ; 2022

In: Frontiers in Astronomy and Space Sciences Vol. 9 ( 2022-9-2)

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In: Frontiers in Astronomy and Space Sciences, Frontiers Media SA, Vol. 9 ( 2022-9-2)

Abstract: Ultra-low frequency (ULF) waves are routinely observed in Earth’s dayside magnetosphere. Here we investigate the influence of externally-driven density variations in the near-Earth space in the ULF regime using global 2D simulations performed with the hybrid-Vlasov model Vlasiator. With the new time-varying boundary setup, we introduce a monochromatic Pc5 range periodic density variation in the solar wind. A breathing motion of the magnetopause and changes in the bow shock standoff position are caused by the density variation, the time lag between which is found to be consistent with propagation at fast magnetohydrodynamic speed. The oscillations also create large-scale stripes of variations in the magnetosheath and modulate the mirror and electromagnetic ion cyclotron modes. We characterize the spatial-temporal properties of ULF waves at different phases of the variation. Less prominent EMIC and mirror mode wave activities near the center of magnetosheath are observed with decreasing upstream Mach number. The EMIC wave occurrence is strongly related to pressure anisotropy and β ‖ , both vary as a function of the upstream conditions, whereas the mirror mode occurrence is highly influenced by fast waves generated from upstream density variations.

Type of Medium: Online Resource

ISSN: 2296-987X

URL: Article

DOI: 10.3389/fspas.2022.984918

DOI: 10.3389/fspas.2022.984918.s001

DOI: 10.3389/fspas.2022.984918.s002

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DOI: 10.3389/fspas.2022.984918.s012

DOI: 10.3389/fspas.2022.984918.s013

Language: Unknown

Publisher: Frontiers Media SA

Publication Date: 2022

detail.hit.zdb_id: 2778829-5

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First 3D hybrid-Vlasov global simulation of auroral proton precipitation and comparison with satellite observations

Grandin, Maxime ; Luttikhuis, Thijs ; Battarbee, Markus ; [et al.]

EDP Sciences ; 2023

In: Journal of Space Weather and Space Climate Vol. 13 ( 2023), p. 20-

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In: Journal of Space Weather and Space Climate, EDP Sciences, Vol. 13 ( 2023), p. 20-

Abstract: The precipitation of charged particles from the magnetosphere into the ionosphere is one of the crucial coupling mechanisms between these two regions of geospace and is associated with multiple space weather effects, such as global navigation satellite system signal disruption and geomagnetically induced currents at ground level. While precipitating particle fluxes have been measured by numerous spacecraft missions over the past decades, it often remains difficult to obtain global precipitation patterns with a good time resolution during a substorm. Numerical simulations can help to bridge this gap and improve the understanding of mechanisms leading to particle precipitation at high latitudes through the global view they offer on the near-Earth space system. We present the first results on auroral (0.5–50 keV) proton precipitation within a 3-dimensional simulation of the Vlasiator hybrid-Vlasov model. The run is driven by southward interplanetary magnetic field conditions with constant solar wind parameters. We find that on the dayside, cusp proton precipitation exhibits the expected energy–latitude dispersion and takes place in the form of successive bursts associated with the transit of flux transfer events formed through dayside magnetopause reconnection. On the nightside, the precipitation takes place within the expected range of geomagnetic latitudes, and it appears clearly that the precipitating particle injection is taking place within a narrow magnetic local time span, associated with fast Earthward plasma flows in the near-Earth magnetotail. Finally, the simulated precipitating fluxes are compared to observations from Defense Meteorological Satellite Program spacecraft during driving conditions similar to those in the simulation and are found to be in good agreement with the measurements.

Type of Medium: Online Resource

ISSN: 2115-7251

URL: Article

DOI: 10.1051/swsc/2023017

Language: English

Publisher: EDP Sciences

Publication Date: 2023

detail.hit.zdb_id: 2628166-1

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Enabling technology for global 3D + 3V hybrid-Vlasov simulations of near-Earth space

Ganse, Urs ; Koskela, Tuomas ; Battarbee, Markus ; [et al.]

AIP Publishing ; 2023

In: Physics of Plasmas Vol. 30, No. 4 ( 2023-04-01)

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In: Physics of Plasmas, AIP Publishing, Vol. 30, No. 4 ( 2023-04-01)

Abstract: We present methods and algorithms that allow the Vlasiator code to run global, three-dimensional hybrid-Vlasov simulations of Earth's entire magnetosphere. The key ingredients that make Vlasov simulations at magnetospheric scales possible are the sparse velocity space implementation and spatial adaptive mesh refinement. We outline the algorithmic improvement of the semi-Lagrangian solver for six-dimensional phase space quantities, discuss the coupling of Vlasov and Maxwell equations' solvers in a refined mesh, and provide performance figures from simulation test runs that demonstrate the scalability of this simulation system to full magnetospheric runs.

Type of Medium: Online Resource

ISSN: 1070-664X , 1089-7674

URL: Article

DOI: 10.1063/5.0134387

Language: English

Publisher: AIP Publishing

Publication Date: 2023

detail.hit.zdb_id: 1472746-8

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Spatial filtering in a 6D hybrid-Vlasov scheme to alleviate adaptive mesh refinement artifacts: a case study with Vlasiator (versions 5.0, 5.1, and 5.2.1)

Papadakis, Konstantinos ; Pfau-Kempf, Yann ; Ganse, Urs ; [et al.]

Copernicus GmbH ; 2022

In: Geoscientific Model Development Vol. 15, No. 20 ( 2022-10-27), p. 7903-7912

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In: Geoscientific Model Development, Copernicus GmbH, Vol. 15, No. 20 ( 2022-10-27), p. 7903-7912

Abstract: Abstract. Numerical simulation models that are used to investigate the near-Earth space plasma environment require sophisticated methods and algorithms as well as high computational power. Vlasiator 5.0 is a hybrid-Vlasov plasma simulation code that is able to perform 6D (3D in ordinary space and 3D in velocity space) simulations using adaptive mesh refinement (AMR). In this work, we describe a side effect of using AMR in Vlasiator 5.0: the heterologous grid approach creates discontinuities due to the different grid resolution levels. These discontinuities cause spurious oscillations in the electromagnetic fields that alter the global results. We present and test a spatial filtering operator for alleviating this artifact without significantly increasing the computational overhead. We demonstrate the operator's use case in large 6D AMR simulations and evaluate its performance with different implementations.

Type of Medium: Online Resource

ISSN: 1991-9603

URL: Article

DOI: 10.5194/gmd-15-7903-2022

Language: English

Publisher: Copernicus GmbH

Publication Date: 2022

detail.hit.zdb_id: 2456725-5

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