| 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 ( | EN | 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. |
Last updated: April 18, 2026 04:26 PM
CO₂
429.8ppm
+-0.2
/ year
CH₄
1945.85ppb
+8.44
/ year
Temp
+1.48°C
Peak +1.73°C
Population
8.1B
+67M
/ year