Why does the magnetotail reconnection have significantly varying strength of fluctuation?

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 (MMS) 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 fluctuation strength (dBrec, dErec) for these reconnections ranges from 0.7 to 10 nT and 0.8 to 30 mV/m, respectively. Our analysis unveils significant correlations between inflow conditions including Alfven speed VA,in, , magnetic disturbances dBin and electric field disturbances dEin with (dBrec, dErec). Fluctuation strength also shows good correlations with interplanetary magnetic field (IMF) 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.