Datensatz

Zusammenfassung

Various mechanisms have been proposed to explain magnetosheath High Speed Jets (HSJs), such as bow shock ripples, solar wind discontinuities, foreshock transients, pressure pulses, nano dust clouds or shock reformation. It is however difficult to associate these to HSJs with the lack of simultaneous measurements at key locations, near the bow shock and both upstream and downstream of it. We will use a special Cluster campaign, where one spacecraft was lagged 8 hours behind the three other spacecraft, to obtain near-Earth solar wind measurements upstream of the bow shock, together with simultaneous measurements in the magnetosheath. The event of interest is first observed by ACE on 13 January 2019, around 07:30 UT, as a short 10-minute period of dominant IMF-Bx (cone angle around 140 deg.). Cluster 1 and Cluster 2 just upstream of the bow shock, observed also such IMF-Bx dominant period together with energetic ions reflected from the bow shock and Hot Flows Anomalies (HFA) at the beginning and end of the IMF-Bx dominant interval. Finally, Cluster 3 and 4 and MMS1-4, a few RE from each other downstream of the shock, observed HSJs imbedded in a turbulent magnetosheath for 15 minutes around 08:30 UT. In the first part of the interval, Cluster 3/4 and MMS1-4 observed five HSJs quasi-simultaneously and in the second part, Cluster 3/4 observed three HSJs and MMS only one. Possible cause of missing HSJs will be investigated. Possible relation of HSJs with foreshock structures observed upstream will also be investigated.