Tracing the ICME plasma with a MHD simulation

Abstract

The determination of the chemical composition of interplanetary coronal mass ejection (ICME) plasma is an open issue. More specifically, it is not yet fully understood how remote sensing observations of the solar corona plasma during solar disturbances evolve into plasma properties measured in situ away from the Sun. The ambient conditions of the background interplanetary plasma are important for space weather because they influence the evolutions, arrival times, and geo-effectiveness of the disturbances. The Reverse In situ and MHD APproach (RIMAP) is a technique to reconstruct the heliosphere on the ecliptic plane (including the magnetic Parker spiral) directly from in situ measurements acquired at 1 AU. It combines analytical and numerical approaches, preserving the small-scale longitudinal variability of the wind flow lines. In this work, we use RIMAP to test the interaction of an ICME with the interplanetary medium. We model the propagation of a homogeneous non-magnetised (i.e. with no internal flux rope) cloud starting at 800 km s−1 at 0.1 AU out to 1.1 AU. Our 3D magnetohydrodynamics (MHD) simulation made with the PLUTO MHD code shows the formation of a compression front ahead of the ICME, continuously driven by the cloud expansion. Using a passive tracer, we find that the initial ICME material does not fragment behind the front during its propagation, and we quantify the mixing of the propagating plasma cloud with the ambient solar wind plasma, which can be detected at 1 AU.

Observation and Modeling of the Solar Wind Turbulence Evolution in the Sub-Mercury Inner Heliosphere

“…The underlying assumption is that the speed of the solar wind, measured by the SPAN-Ai top-hat electrostatic analyzer of the Solar Wind Electrons Alphas & Protons suite (SWEAP; Kasper et al 2016) on board PSP, is constant during its propagation to BC. Although impossible to fully corroborate (given the lack of BC plasma data), this ballistic assumption is reasonable based on the most recent observational and modeling studies carried out during the first SolO-PSP quadrature (Telloni et al 2021b;Adhikari et al 2022a;Biondo et al 2022;Telloni et al 2022a ), which show that the plasma flow reaches a steady-state speed at about 0.1 au from the Sun. Using this technique and assumption, it turns out that the plasma crossing PSP on 2022 February 24 from 04:15 to 05:37 UT impinged BC 1.23 days later, on 2022 February 25, at 09:48-11:10 UT.…”

“…As such, C ∼ 1 (C = 1) indicates a predominance of compressive (noncompressive) fluctuations in the solar wind (Bavassano et al 1982a). Intermittency (a key ingredient of turbulence) affects the distribution functions of a fluctuating field by causing them to become gradually more peaked as smaller scales are involved (see Bruno & Carbone 2013). As a measure of the peakedness of a distribution (e.g., Frisch 1995; Dudok de Wit et al 2013), the faster  grows continually at smaller scales (higher frequencies), the more intermittent the solar wind fluctuations are.…”

“…At large distances from the Sun (i.e., >0.3 au), the solar wind can be reasonably considered to be in a state of fully developed turbulence. Fluctuations in the magnetic field, as well as in the plasma parameters, are indeed observed over a wide range of scales (Bruno & Carbone 2013). Additionally, their spectral (Coleman 1968) and intermittency (Sorriso-Valvo et al 1999) properties suggest that the solar wind flow is at a high Reynolds number (Sorriso-Valvo et al 1999;Parashar et al 2019).…”

“…The evolution of turbulence in the solar wind during its outward expansion is a central topic in heliophysics. Significant advances have been made over the past decades in observations, theory, and numerical simulations of solar wind turbulence (see the exhaustive review by Bruno & Carbone 2013). Nevertheless, there is still no complete, satisfactory description of solar wind turbulence evolution, namely, how and where turbulence is generated; how solar wind expansion, nonlinear interactions, and/or other mechanisms, such as plasma instabilities, collude in driving its development; and at what distance from the Sun turbulence reaches, in its spectral properties, the well-known flavor described by Kolmogorov (1941).…”

Multispacecraft Remote Sensing and In Situ Observations of the 2020 November 29 Coronal Mass Ejection and Associated Shock: From Solar Source to Heliospheric Impacts

“…The multispacecraft measurements at different locations can determine the propagation and expansion characteristics of CMEs/shocks along different directions, including the evolution anisotropy of CMEs/shocks resulting from different background solar wind. Multipoint in situ measurements are also needed to verify the forecasting accuracy along different directions of a magnetohydrodynamics model in a same event simulation (e.g., Reinard et al 2012;Biondo et al 2021).…”