2026-01-14 東京大学
本研究で実施した太陽プラズマ噴出物の多点観測の概念図
＜関連情報＞
- https://www.s.u-tokyo.ac.jp/ja/press/11022/
- https://iopscience.iop.org/article/10.3847/1538-4357/ae1834
フォーブッシュ減少の多点観測により明らかになった2022年3月の惑星間コロナ質量放出の時空間的進化 Spatiotemporal Evolution of the 2022 March Interplanetary Coronal Mass Ejection Revealed by Multipoint Observations of Forbush Decreases
Gaku Kinoshita, Beatriz Sanchez-Cano, Yoshizumi Miyoshi, Laura Rodríguez-García, Emilia Kilpua, Benoit Lavraud, Mathias Rojo, Marco Pinto, Yuki Harada, Go Murakami,…
The Astrophysical Journal Published: 2026 January 13
DOI:10.3847/1538-4357/ae1834
Abstract
Interplanetary coronal mass ejections (ICMEs) cause “Forbush decreases” (FDs), which are local decreases in background galactic cosmic rays (GCRs). Even though FDs can be observed with simple particle instruments, their amplitude and shape provide physical profiles of passing ICMEs. However, in some cases, previous statistical studies of the heliocentric distance dependence of FD changes associated with ICME propagation have found no strong correlation. We need the criteria for evaluating the relationship between ICME structure and FDs, necessary for the FD’s statistical analysis. This study investigates the effect of the evolution and interactions of ICMEs on FD profiles in the inner solar system using multipoint comparisons. We focus on multipoint ICME observations by Solar Orbiter, BepiColombo, and near-Earth spacecraft from 2022 March 10 to 16, when these spacecraft were ideally located for studying the radial and longitudinal evolution of ICMEs and accompanying FDs. We compared GCR variations with the multiple in situ data and ICME model, clarifying the correspondence between the evolution of each ICME structure in the radial and azimuthal directions and the depth and gradients of the FD. The radial comparison revealed decreases in FD intensities and gradients associated with the expansion of the ICME. The longitudinal difference found in FD intensity indicates longitudinal variations of the ICME’s shielding effect. These results suggest that accurate multipoint FD comparisons require determining the relationship between the observer’s position and the inner structure of the passing ICMEs.
