The kinetic ballooning/interchange instability (BICI) was recently found to produce azimutally narrow interchange heads extending into the dipole region from a reversed radial gradient of B$_Z$ in the near-Earth magnetotail. In their nonlinear evolution individual heads were predicted to detach from the reversed B$_Z$ gradient and grow into transient earthward moving northward magnetic field intensifications (dipolarization fronts; DFs). The distinguished signatures of such fronts would be their oblique propagation and cross-tail localization due to the finite k$_y$ structure of the BICI modes. Simultaneous conjugate observations of DFs by THEMIS probes at 11 Earth’s radii (R$_E$) downtail and of sudden brightening and growth of individual auroral beads by the all sky imagers on the ground have been suggested to be ionospheric signature of detached magnetotail interchange heads [Panov et al., 2019]. Here we compare such DFs with a simulated interchange head during later(detachment)-stage BICI head development. The comparison reveals similarly structured leading edges and trailing tails in both the observed DFs and the simulated BICI head. We further identify THEMIS trajectories through the DFs and find that the trajectories were due to oblique (earthward and dawnward) DF propagation. This analysis further supports the idea that BICI indeed releases obliquely propagating azimuthally localized dipolarization fronts in the Earth’s magnetotail.

As it was recently predicted, the kinetic ballooning/interchange instability (BICI) can provoke reconnection onsets that lead to detached azimuthally thin earthward intrusions (heads) of depleted plasma tubes when 𝛽eq ⩽ 100. Such detached BICI heads would be seen as localized earthward-propagating dipolarization fronts. Using Time History of Events and Macroscale Interactions during Substorms observations in the plasma sheet at XGSM ≈ −11 Re and conjugate All-Sky Imager and magnetometer networks observations on the ground, we show four examples when prominent dipolarization fronts with moderate earthward flows were observed amidst azimuthally drifting interchange heads and concurrently with the ionospheric current intensifications near Time History of Events and Macroscale Interactions during Substorms footprints and auroral bright spots originating from dimmer azimuthal beads/rays. These events support the idea that some of the BICI heads detach from the region with reversed radial gradient of Bz. The detached BICI heads propagate earthward-driving ionospheric pseudo-breakups.