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The terrestrial magnetosheath (MS) represents a turbulent, high-beta, compressional, sporadically Alfvenic environment which contains the shocked solar wind (SW) magnetized plasma permeated with waves, instabilities and structures of various origins. In the processes of interaction of the structured SW with the shock and the MS, the electromagnetic, kinetic and thermal energies are transported between locations, transferred between scales, conversed between each other and finally dissipated. Similarly to the SW case the energy transfer in MS is expected to be manifested in typical scalings seen in power spectral densities of various field and plasma parameters over the fluid (inertial-range) and kinetic ion-electron scales. However, near the sub-solar dayside MS the inertial-range turbulent cascade is usually absent, while the kinetic range scaling roughly remains the same as in the SW. Observations of short magnetic correlation lengths near the sub-solar MS also confirm the absence of large-scale magnetic fluctuations which could populate the inertial-range of scales. Without the inertial range energy cascade the kinetic range turbulence should exhibit a fast decay downstream of the shock, but it is not observed. We argue that to understand the spectral scalings in the MS the whole energy budget has to be considered including possible nonlocal energy transfer terms. By using MMS data in the MS we show that, when the inertial range is present, the turbulent energy dissipation rate can be estimated by the energy transfer rate from both the Yaglom law and from the pressure-strain interaction term. When the inertial range is absent and the Yaglom law cannot be used, the dissipation rate can still be estimated by using the pressure-strain term.

Large scale solar wind (SW) structures called Coronal Mass Ejections (CMEs) and Stream Interaction Regions (SIRs) propagate through the interplanetary medium, where they might impact Earth and cause jet-like disturbances in the magnetosheath. Such jets are short scale structures characterized by an enhancement in dynamic pressure that propagate through the Earth’s magnetosheath (EMS) transporting mass, momentum and energy being able to affect and perturb the Earth’s magnetosphere.Jets have been studied for 20 years, but how different SW conditions triggered by CMEs and SIRs affect jet production is a topic that has only recently begun to be studied. In this work we characterize jets observed by THEMIS during a CME and a SIR passage. We find clear differences in number and size between the jets associated with the CME regions arriving at the EMS as well as in comparison with the characteristics of jets associated with the SIR passage. Comparing WIND and THEMIS data we discuss how these differences are linked to the SW conditions in the context of a recent statistical study (Koller et al. 2022) and with different jet generation mechanisms.

Magnetic holes are significant depressions of the interplanetary magnetic field (IMF) that can be found embedded in the solar wind everywhere within the heliosphere. They resemble mirror mode magnetic structures that form as a response to excess perpendicular temperatures. Magnetic holes situated at IMF discontinuities (current sheets) may also be the result of reconnection. Magnetic holes occur more often under fast solar wind conditions, and their scale sizes are known to be on the order of thousands to tens of thousands of km, determined essentially from temporal width and plasma velocity observations. So far, the scale sizes have only been estimated for the directions parallel to the respective solar wind plasma flows. In this study, we attempt to calculate the first distributions of the scale sizes for the orthogonal, flow-perpendicular directions. Therefore, we use multi-point observations of magnetic holes by the ARTEMIS spacecraft in lunar orbit. The method we use has been previously applied to plasma jets present in the magnetosheath of Earth. The knowledge of the flow-perpendicular scale sizes is important to assess the holes’ impact on planetary magnetospheres and cometary environments.

Large-scale solar wind (SW) structures like coronal mass ejections (CMEs) and stream interaction regions (SIRs) significantly alter the plasma within the Earth’s magnetosheath and change the foreshock region. Thus, they modulate the number and the parameters of dynamic pressure transients in the magnetosheath, which we call magnetosheath jets. We use THEMIS spacecraft data from 2008 to 2022 to detect these jets in the magnetosheath and OMNI data for the SW within the same time range. We investigate which properties in each SW structure primarily influence the jet occurrence. We find that CMEs cause a reduction in jet occurrence due to the mix of high magnetic field strength, high plasma beta, low Mach number, and high cone angles. These conditions most likely disrupt the building of a proper foreshock region and thus hinder the major generation mechanism for jets in the magnetosheath. On the other hand, high speed streams in SIRs show favorable conditions for jet generation in all plasma parameters, most importantly due to the high probability for low cone angles, the low density, high velocity, and low magnetic field strength. We analyze how the jet parameters differ in each type of SW structure and discuss how this influences the geoeffectiveness of jets.

The Kelvin-Helmholtz (KH) instability is a shear-driven instability commonly observed at the Earth’s magnetopause under different solar wind conditions. The evolution of the KH instability is characterised by the nonlinear coupling of different modes, which tend to generate smaller and smaller vortices along the shear layer. Such a process leads to the conversion of energy due to the large-scale motion of the shear flow into heat contributing to the local heating and the generation of a turbulent environment. On the other hand, it allows the entry of the dense and cold solar wind plasma into the tenuous and hot magnetosphere, thus favoring the mixing of these two different regions.In this context, we introduce a new quantity, the so-called mixing parameter, which can identify the vortex boundaries and distinguish among different types of KH structures crossed by the spacecraft. The mixing parameter exploits the well distinct particle energies which characterise the magnetosphere and magnetosheath plasmas by using only single-spacecraft measurements [1]. The mixing parameter is therefore used to conduct a statistical analysis of the evolution of KH structures observed by the Magnetospheric Multiscale mission in the near Earth’s environment for two specific interplanetary magnetic field configurations: northward and southward. Moreover, in situ measurements are compared with kinetic KH instability simulations modeling realistic conditions observed by the satellites. The good agreement between synthetic data and in situ observations further strengthen our interpretation of the mixing parameter features and results. [1] Settino, A., et al. (2022) Journal of Geophysical Research: Space Physics, 127, e2021JA029758.