Characteristic Scales of Complexity and Coherence within Interplanetary Coronal Mass Ejections: Insights from Spacecraft Swarms in Global Heliospheric Simulations

Abstract

Many aspects of the three-dimensional (3-D) structure and evolution of interplanetary coronal mass ejections (ICMEs) remain unexplained. Here, we investigate two main topics: (1) the coherence scale of magnetic fields inside ICMEs, and (2) the dynamic nature of ICME magnetic complexity. We simulate ICMEs interacting with different solar winds using the linear force-free spheromak model incorporated into the EUHFORIA model. We place a swarm of ~20000 spacecraft in the 3-D simulation domain and characterize ICME magnetic complexity and coherence at each spacecraft based on simulated time series. Our simulations suggest that ICMEs retain a lower complexity and higher coherence along their magnetic axis, but that a characterization of their global complexity requires crossings along both the axial and perpendicular directions. For an ICME of initial half angular width of $45^{\circ }$ that does not interact with other large-scale solar wind structures, global complexity can be characterized by as little as 7-12 spacecraft separated by $25^{\circ }$, but the minimum number of spacecraft rises to 50-65 (separated by $10^{\circ }$) if interactions occur. Without interactions, ICME coherence extends for $45^{\circ }$, $20^{\circ }$-$30^{\circ }$, $15^{\circ }$-$30^{\circ }$, and $0^{\circ }$-$10^{\circ }$ for $B$, $B_{\varphi }$, $B_{\theta }$, and $B_r$, respectively. Coherence is also lower in the ICME west flank compared to the east flank due to Parker spiral effects. Moreover, coherence is reduced by a factor of 3-6 by interactions with solar wind structures. Our findings help constrain some of the critical scales that control the evolution of ICMEs and aid in the planning of future dedicated multi-spacecraft missions.

References in corpus (12)

• Origins of the Ambient Solar Wind: Implications for Space Weather
• Decoding the Pre-Eruptive Magnetic Field Configurations of Coronal Mass Ejections
• FRiED: A novel three-dimensional model of coronal mass ejections
• Observation-based modelling of magnetised Coronal Mass Ejections with EUHFORIA
• Multi point analysis of coronal mass ejection flux ropes using combined data from Solar Orbiter, BepiColombo and Wind
• First simultaneous in situ measurements of a coronal mass ejection by Parker Solar Probe and STEREO-A
• The effect of stream interaction regions on ICME structures observed in longitudinal conjunction
• Causes and Consequences of Magnetic Complexity Changes within Interplanetary Coronal Mass Ejections: a Statistical Study
• A Coronal Mass Ejection and Magnetic Ejecta Observed In Situ by STEREO-A and Wind at 55${}^{\circ }$ Angular Separation
• Exploring the radial evolution of Interplanetary Coronal Mass Ejections using EUHFORIA
• Evolution of interplanetary coronal mass ejection complexity: a numerical study through a swarm of simulated spacecraft
• Multi-Spacecraft Observations of the Evolution of Interplanetary Coronal Mass Ejections Between 0.3 and 2.2 AU: Conjunctions with the Juno Spacecraft

Cited by in corpus (2)

• A coronal mass ejection encountered by four spacecraft within 1 au from the Sun: Ensemble modelling of propagation and magnetic structure
• Coronal electron density: Insights from radio and in situ observations, and EUHFORIA modeling