Characterizing Alfvénicity and Proton Temperature Distributions in Interplanetary Coronal Mass Ejection Magnetic Clouds

Abstract We investigated a comprehensive sample of 474 interplanetary coronal mass ejection (ICME) events observed by the Wind spacecraft to examine the Alfvénic characteristics within their magnetic cloud regions. The analysis focuses on identifying inward and outward Alfvénic fluctuations of the magnetic and velocity field components. Our results reveal that approximately 74.68% of ICME magnetic cloud regions are non-Alfvénic, while 25.32% exhibit clear Alfvénic signatures, predominantly characterized by outward fluctuations. Furthermore, the temperature distribution shows a substantial enhancement in Alfvénic regions compared to non-Alfvénic ones, with proton temperatures elevated up to ∼33 eV. These findings suggest that Alfvénic fluctuations may play a significant role in the localized plasma heating within ICME structures and provide potential constraints on their broader contribution to space plasma environments.