  We present detailed analysis of the turbulence observed in three-dimensional
particle-in-cell simulations of magnetic reconnection at the magnetopause. The
parameters are representative of an electron diffusion region encounter of the
Magnetospheric Multiscale (MMS) mission. The turbulence is found to develop
around both the magnetic X line and separatrices, is electromagnetic in nature,
is characterized by a wave vector $k$ given by
$k\rho_e\sim(m_eT_e/m_iT_i)^{0.25}$ with $\rho_e$ the electron Larmor radius,
and appears to have the ion pressure gradient as its source of free energy.
Taken together, these results suggest the instability is a variant of the lower
hybrid drift instability. The turbulence produces electric field fluctuations
in the out-of-plane direction (the direction of the reconnection electric
field) with an amplitude of around $\pm 10$~mV/m, which is much greater than
the reconnection electric field of around $0.1$~mV/m. Such large values of the
out-of-plane electric field have been identified in the MMS data. The
turbulence in the simulations controls the scale lengths of the density profile
and current layers in asymmetric reconnection, driving them closer to
$\sqrt{\rho_e\rho_i}$ than the $\rho_e$ or $d_e$ scalings seen in 2-D
reconnection simulations, and produces significant anomalous resistivity and
viscosity in the electron diffusion region.

Space Physics;Plasma Physics