Observations of the Magnetopause Reconnection Ion Diffusion Region With High‐Density O + Ions During the May 2024 Superstorm
Year: 2026
Type: article
Abstract: Based on high‐resolution measurements from NASA's Magnetospheric Multiscale mission (MMS), we present the first direct observation of an ion diffusion region (IDR) with high number density O + ions within dayside magnetopause reconnection during the May 2024 superstorm. The O + ion density reaches a high value of ∼3.3 cm −3 . It helps study heavy‐ion dynamics in dayside magnetopause reconnection. In the vicinity of IDR, O + ions exhibit distinct acceleration to 300 km/s along the normal direction caused by the enhanced Hall electric field (| E N | max ≈ 80 mV/m). The distorted ion velocity distributions reveal the complex energization processes in the IDR. Crucially, these O + ion dynamics can reduce reconnection rate by ∼10.3%–25.3%, providing the result that heavy‐ion can substantially alter magnetopause reconnection physics during the superstorm. This study advances our understanding of magnetopause reconnection by demonstrating that storm‐enhanced O + populations modify the structure of diffusion regions, particle energization, and reconnection rate.
Source: Geophysical Research Letters
DOI: 10.1029/2025gl121449
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,190
OpenAlex ID: W7154707361