Vlasiator Hybrid-Vlasov Simulations and MMS Observations of Flux Transfer Events: a Comparative Analysis
Abstract
The Vlasiator hybrid-Vlasov code was developed to investigate global magnetospheric dynamics at ion-scales. Here, we particularly focus on the role of magnetic reconnection in the formation and evolution of the Vlasiator magnetic islands at the low-latitude magnetopause. The simulation results indicate that: 1) the ion kinetics inside the reconnection ion diffusion region, including the Larmor electric field on the magnetospheric-side of the X-point and the corresponding three-dimensional crescent-shaped ion distributions, are well-captured by the code, 2) magnetic islands evolve due to continuous reconnection at the adjacent X-points, 'coalescence' which involves the merging of neighboring islands to create a larger island, 'erosion' during which an island loses magnetic flux due to reconnection, and 'division' which involves the splitting of an island into smaller islands, and 3) continuous reconnection at the adjacent X-points is the dominant supplier of magnetic flux and plasma to the outer layers of magnetic islands resulting in growth rates up to +2.4 Wb/s-km. The simulation results are validated by comparison to Magnetospheric Multiscale (MMS) measurements for a selected chain of flux transfer events (FTEs). In particular, in-situ MMS observations of ion-inertial length-scale FTEs located inside a current sheet between two dominant X-lines reveal: 1) crescent-shaped ion populations, and 2) normalized reconnection rates up to 0.18, in agreement with theory and the Vlasiator predictions. Based on the simulation results and the MMS-observed reconnection rate, it is estimated that di-scale FTEs can grow Earth-sized, ~350 di, within < 2.0 minutes, nearly 10 times faster than previously reported.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSM21C3183A
- Keywords:
-
- 7835 Magnetic reconnection;
- SPACE PLASMA PHYSICS;
- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS;
- 7863 Turbulence;
- SPACE PLASMA PHYSICS;
- 7867 Wave/particle interactions;
- SPACE PLASMA PHYSICS