Study on the vorticity field within the tail reconnection jet by the MMS
spacecraft
Abstract
Based on direct measurement by the MMS spacecraft in the years of 2017
and 2018, we perform studies on the vorticity field () within the
reconnection jet in the plasma sheet. A typical event on 26 July 2017
shows clearly the evolution of the field with the jet velocity: is weak
in the decelerated BBF and strong in the fast BBF. The strongest -field
is in the decaying BBF, around the dipolarization fronts. Despite the
evolution of the BBF, the -field is characterized by the perpendicular
vorticity (ω). Statistical results confirm the close correlation between
BBF and . Higher means stronger . This accounts for the dawn-dusk
asymmetry of the -field. The anisotropic is more significant in the
V-dominating BBF than in the V-dominating BBF. The -field within the
reconnection jet is β-dependence. The β-dependence -field tends to be
stronger in super-M jet than in sub-M jet.