loading page

Classifying Magnetosheath Jets using MMS - Statistical Properties
  • +2
  • Savvas Raptis,
  • Tomas Karlsson,
  • Ferdinand Plaschke,
  • Anita Kullen,
  • Per-Arne Lindqvist
Savvas Raptis
Royal Institute of Technology, Royal Institute of Technology, Royal Institute of Technology

Corresponding Author:[email protected]

Author Profile
Tomas Karlsson
KTH Royal Institute of Technology, KTH Royal Institute of Technology, KTH Royal Institute of Technology
Author Profile
Ferdinand Plaschke
Space Research Institute, Austrian Academy of Sciences, Space Research Institute, Austrian Academy of Sciences, Space Research Institute, Austrian Academy of Sciences
Author Profile
Anita Kullen
KTH Royal Institute of Technology, KTH Royal Institute of Technology, KTH Royal Institute of Technology
Author Profile
Per-Arne Lindqvist
KTH, Stockholm, Sweden, KTH, Stockholm, Sweden, KTH, Stockholm, Sweden
Author Profile

Abstract

Using Magnetospheric Multiscale (MMS) data, we find, classify and analyze transient dynamic pressure enhancements in the magnetosheath (jets) from May 2015 until May 2019. A classification algorithm is presented, using in-situ MMS data to classify jets (n = 8499) into different categories according to their associated angle between IMF and the bow shock normal vector ( θ ). Jets appearing for θ < 45° are referred to as quasi-parallel, while jets appearing for θ > 45° as quasi-perpendicular jets. Furthermore, we define those jets that occur at the boundaries between quasi-parallel and quasi-perpendicular magnetosheath as boundary jets. Finally, encapsulated jets are jet-like structures with similar characteristics to quasi-parallel jets while the surrounding plasma is of quasi-perpendicular nature. We present the first statistical results of such a classification and provide comparative statistics for each class. Furthermore, we investigate correlations between jet quantities. Quasi-parallel jets have the highest dynamic pressure while occurring more often than quasi-perpendicular jets. The infrequent quasi-perpendicular jets, have a much smaller duration, velocity, and density and are therefore relatively weaker. We conclude that quasi-parallel and boundary jets have similar properties and are unlikely to originate from different generation mechanisms. Regarding the encapsulated jets, we suggest that they are a special subset of quasi-parallel jets originating from the flanks of the bow shock, for large IMF cone angles although a relation to FTEs and magnetospheric plasma is also possible. Our results support existing generation theories, such as the bow shock ripple and SLAMS-associated mechanisms while indicating that other factors may contribute as well.
Nov 2020Published in Journal of Geophysical Research: Space Physics volume 125 issue 11. 10.1029/2019JA027754