Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/angeo-2018-22
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Regular paper
15 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Annales Geophysicae (ANGEO).
Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation
Xochitl Blanco-Cano1, Markus Battarbee2, Lucile Turc2, Andrew P. Dimmock3,8, Emilia K. J. Kilpua2, Sanni Hoilijoki4, Urs Ganse2, David G. Sibeck5, Paul A. Cassak6, Robert C. Fear7, Riku Jarvinen8,9, Liisa Juusola9,2, Yann Pfau-Kempf2, Rami Vainio10, and Minna Palmroth2,9 1Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Mexico
2Department of Physics, University of Helsinki, Helsinki, Finland
3Swedish Institute of Space Physics, Uppsala, Sweden
4Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA
5NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
6Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia, USA
7Department of Physics & Astronomy, University of Southampton, Southampton, UK
8Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, Espoo, Finland
9Finnish Meteorological Institute, Helsinki, Finland
10Department of Physics and Astronomy, University of Turku, Turku, Finland
Abstract. In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the downstream region, and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angles spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.
Citation: Blanco-Cano, X., Battarbee, M., Turc, L., Dimmock, A. P., Kilpua, E. K. J., Hoilijoki, S., Ganse, U., Sibeck, D. G., Cassak, P. A., Fear, R. C., Jarvinen, R., Juusola, L., Pfau-Kempf, Y., Vainio, R., and Palmroth, M.: Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation, Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2018-22, in review, 2018.
Xochitl Blanco-Cano et al.
Xochitl Blanco-Cano et al.
Xochitl Blanco-Cano et al.

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Short summary
We use the Vlasiator code to study the characteristics of transient structures that exist in the earth's foreshock, i.e., upstream of the bow shock. The structures are cavitons and spontaneous hot flow anomalies (SHFA). These transients can interact with the bow shock. We study the changes that the shock suffers via this interaction. We also investigate ion distributions associated with the cavitons and SHFA. A very important results is that the arrival of multiple SHFA results in shock erosion.
We use the Vlasiator code to study the characteristics of transient structures that exist in the...
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