Flux Transfer Event Showers at Mercury: Dependence on Plasma β and Magnetic Shear and Their Contribution to the Dungey Cycle

Mercury's flux transfer event (FTE) showers are dayside magnetopause crossings accompanied by large numbers (≥ 10) of magnetic flux ropes (FRs). These shower events are common, occurring during 52% (1953/3748) of the analyzed crossings. Shower events are observed with magnetic shear angles (θ) from 0° to 180° across the magnetopause and magnetosheath plasma β from 0.1 to 10, but are most prevalent for high θ and low plasma β. Individual FR duration correlates positively, while spacing correlates negatively, with θ and plasma β. FR flux content and core magnetic field intensity correlate negatively with plasma β, but they do not correlate with θ. During shower intervals, FRs carry 60% to 85% of the magnetic flux required to supply Mercury's Dungey cycle. The FTE showers and the large amount of magnetic flux carried by the FTE‐type FRs appear quite different from observations at Earth and other planetary magnetospheres visited thus far.