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Volume 36, issue 4 | Copyright
Ann. Geophys., 36, 1117-1129, 2018
https://doi.org/10.5194/angeo-36-1117-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 16 Aug 2018

Regular paper | 16 Aug 2018

Data mining for vortices on the Earth's magnetosphere – algorithm application for detection and analysis

Yaireska M. Collado-Vega1, Virginia L. Kalb2, David G. Sibeck1, Kyoung-Joo Hwang3, and Lutz Rastätter1 Yaireska M. Collado-Vega et al.
  • 1NASA Goddard Space Flight Center, Space Weather Laboratory, Code 674, Greenbelt, MD, USA
  • 2NASA Goddard Space Flight Center, Terrestrial Information Systems, Code 619, Greenbelt, MD, USA
  • 3Southwest Research Institute, San Antonio, TX, USA

Abstract. Unsteady processes in the solar wind–magnetosphere interaction, such as vortices developed at the magnetopause boundary by the Kelvin–Helmholtz instability, may contribute to the process of mass, momentum and energy transfer into the Earth's magnetosphere. The research described in this paper validates an algorithm to automatically detect and characterize vortices based on velocity data from simulations. The vortex identification algorithm (VIA) systematically searches the 3-D velocity fields to identify critical points where the magnitude of the velocity vector vanishes. The velocity gradient tensor is computed and its invariants are used to assess vortex structure in the flow field. We use the Community Coordinated Modeling Center (CCMC) Runs on Request capability to create a series of model runs initialized from the conditions observed by the Cluster mission in the Hwang et al. (2011) analysis of Kelvin–Helmholtz vortices observed during southward interplanetary magnetic field (IMF) conditions. We analyze further the properties of the vortices found in the runs, including the velocity changes within their motion across the magnetosheath. We also demonstrate the potential of our tool to identify and characterize other transient features (e.g., flux transfer events, FTEs) with vortical internal structures. We find that the vortices are associated with flows on the magnetosheath side of the magnetopause that reach speeds greater than the solar wind speed at the bow shock.

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This paper describes an algorithm that automatically detects vortices around the Earth's magnetosphere using the velocity field from simulated data. It also describes how the tool can be used to analyze further properties of the vortices including the velocity changes within their motion across the magnetosheath. Vortices developed at the magnetopause boundary contribute to the process of mass, momentum and energy transfer from the solar wind into the Earth's magnetosphere.
This paper describes an algorithm that automatically detects vortices around the Earth's...
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