Magnetic reconnection in the Earth's magnetosphere is usually manifested as a turbulent state in which the large-amplitude fluctuations disrupt the main reconnection layer, while it occasionally shows a clear structured reconnection layer with weak fluctuations, i.e., a laminar state. To understand why the fluctuation strength varies significantly among reconnection in the Earth's magnetotail, we have examined tens of reconnection events in the Earth's magnetotail observed by the magnetospheric multi-scale mission. We primarily examine the correlation between fluctuation strength in reconnection, quantified by dBrec and dErec, and reconnection inflow conditions and upstream solar wind conditions. The observed fluctuation strength spans 0.7–10 nT for dBrec and 0.8–30 mV/m for dErec. Our analysis unveils significant correlations between inflow conditions including Alfvén speed VA,in and inflow plasma βin, magnetic disturbances dBin, and electric field disturbances dEin with (dBrec, dErec). The fluctuation strength also shows good correlations with the interplanetary magnetic field cone angle and solar wind dynamic pressure, whereas it has an unclear relationship with substorm and storm activities. We suggest that inflow reconnection conditions act as the principal catalysts for turbulence during reconnection.
Jin et al. (Sun,) studied this question.