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Magnetosheath jets constitute a significant coupling effect between the solar wind (SW) and the magnetosphere of the Earth. In order to investigate the effects and forecasting of these jets, we present the first-ever statistical study of the jet production during large-scale SW structures like coronal mass ejections (CMEs), stream interaction regions (SIRs) and high speed streams (HSSs). Magnetosheath data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft between January 2008 and December 2020 serve as measurement source for jet detection. Two different jet definitions were used to rule out statistical biases induced by our jet detection method. For the CME and SIR + HSS lists, we used lists provided by literature and expanded on incomplete lists using OMNI data to cover the time range of May 1996 to December 2020. We find that the number and total time of observed jets decrease when CME-sheaths hit the Earth. The number of jets is lower throughout the passing of the CME-magnetic ejecta (ME) and recovers quickly afterward. On the other hand, the number of jets increases during SIR and HSS phases. We discuss a few possibilities to explain these statistical results.

Output files from 2.5D local hybrid simulations of collisionless shocsk that were used to create Figures 1 and 2 of the paper "ULF wave transmission across collisionless shocks: 2.5D local hybrid simulations" (currently under review). Each file containsX and Y coordinates and the Bx, By, Bz, and B values. The shock parameters were Bf_119.txt - Vinflow = 3.3 V$_A$ (Alfvén speed), $'theta_{BN}$ = 15$^\circ$, $\beta$=0.5, M$_A$=4.29. Bf_098.txt - Vinflow = 3.3 V$_A$ (Alfvén speed), $'theta_{BN}$ = 45$^\circ$, $\beta$=0.5, M$_A$=4.48. Bf_096.txt - Vinflow = 3.3 V$_A$ (Alfvén speed), $'theta_{BN}$ = 50$^\circ$, $\beta$=0.5, M$_A$=4.57. Bf_089.txt - Vinflow = 4.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 15$^\circ$, $\beta$=0.5, M$_A$=5.71. Bf_088.txt - Vinflow = 4.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 45$^\circ$, $\beta$=0.5, M$_A$=5.82. Bf_080.txt - Vinflow = 4.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 50$^\circ$, $\beta$=0.5, M$_A$=5.94. Bf_079.txt - Vinflow = 4.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 15$^\circ$, $\beta$=0.5, M$_A$=6.05. Bf_076.txt - Vinflow = 5.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 30$^\circ$, $\beta$=0.5, M$_A$=6.97. Bf_070.txt - Vinflow = 5.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 45$^\circ$, $\beta$=0.5, M$_A$=7.07. Bf_068.txt - Vinflow = 5.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 50$^\circ$, $\beta$=0.5, M$_A$=7.17. Bf_057.txt - Vinflow = 5.5 V$_A$ (Alfvén speed), $'theta_{BN}$ = 15$^\circ$, $\beta$=0.5, M$_A$=7.42.

We report the ground-level detection of a Galactic Cosmic-Ray (GCR) flux enhancement lasting $\sim$ 17 hr and associated with the passage of a magnetic flux rope (MFR) over the Earth. The MFR was associated with a slow Coronal Mass Ejection (CME) caused by the eruption of a filament on 2016 October 9. Due to the quiet conditions during the eruption and the lack of interactions during the interplanetary CME transport to the Earth, the associated MFR preserved its configuration and reached the Earth with a strong magnetic field, low density, and a very low turbulence level compared to the local background, thus generating the ideal conditions to redirect and guide GCRs (in the $\sim$ 8 to 60 GV rigidity range) along the magnetic field of the MFR. An important negative $B_Z$ component inside the MFR caused large disturbances in the geomagnetic field and a relatively strong geomagnetic storm. However, these disturbances are not the main factors behind the GCR enhancement. Instead, we found that the major factor was the alignment between the MFR axis and the asymptotic direction of the observer.

Magnetosheath jets and plasmoids are very common phenomena downstream of Earth’s quasi-parallel bow shock. As the increase of the dynamic pressure is one of the principal characteristics of magnetosheath jets, the embedded paramagnetic plasmoids have been considered as an special case of the former. Although the properties of both types of structures have been widely studied during the last 20 years, their formation mechanisms have not been examined thoroughly. In this work we perform a 2D local hybrid simulation (kinetic ions – fluid electrons) of a quasi-parallel (θ Bn = 15°), supercritical (M A = 7) collisionless shock in order to study these mechanisms. Specifically, we analyze the formation of one jet and one plasmoid, showing for the first time that they can be produced by different mechanisms related to the same shock. In our simulation, the magnetosheath jet is formed according to the mechanism proposed by Hietala, where at the shock ripples the upstream solar wind suffers locally less deceleration and the flow is focused in the downstream side, producing a compressed and high-velocity region that leads to an increase of dynamic pressure downstream of the shock. The formation of the plasmoid, however, follows a completely new scenario being generated by magnetic reconnection between two plasma layers with opposite B-field orientation in the region just behind the shock.