Alignment of high-latitude ionospheric and thermospheric Lagrangian coherent structures

Lagrangian coherent structures (LCSs), which are objective ridges in time-evolving flows that describe the tendency of neighboring fluid elements to separate, provides a unique opportunity to infer the dynamics in the IT system. In this work, we model IT flows with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model and identify the LCSs.

We compare the LCSs in the neutral winds and plasma drifts during quiet times versus during active times. We find that LCSs are largely aligned in the modeled IT flows, with a dawn-dusk asymmetry in their latitudinal position. During a geomagnetic storm, the thermospheric LCSs (T-LCSs) and ionospheric LCSs (I-LCSs) shift equatorward, align more closely with each other, and maintain a dawn-dusk asymmetry.