Controls on Solar Wind Entry Identified Through Wind–ACE Heavy‐Ion Diagnostics

Abstract

Solar wind (SW) entry into the magnetosphere occurs through several mechanisms, but their dependence on the properties of different ion species is unknown. We compare measurements from Wind‐STICS (magnetosphere) with ACE‐SWICS (L1) to test for any preferential entry between He ²⁺ and SW heavy ions. We utilize a scaling factor, , between upstream and magnetospheric measurements of [ +  + ]/. We analyze ’s variation for different upstream conditions: IMF, N _SW , P _Dyn , and V _SW . Our results reveal that ∼ 1 during strong driving, but >1 during weak driving, meaning that heavier SW ions enter the magnetosphere more efficiently than He ²⁺ .We suggest this is due to their larger gyroradii.