Lagrangian coherent structures in the thermosphere: Predictive transport barriers

Lagrangian coherent structures (LCSs) in the time-varying flow of the upper atmosphere are found. The Horizontal Wind Model 2014 (HWM14) is used to simulate the neutral winds of the thermosphere at 150, 250, and 350 km altitude, for quiet and active geomagnetic conditions. Then LCS analysis of HWM14 winds at 100 km altitude is used to investigate space shuttle water vapor plume transport. LCSs are found to exist in the lower thermosphere, but are more prominent at 250 km and 350 km, at 40° - 80° latitudes on the dayside. Ionosphere-thermosphere coupling manifests in the response of thermospheric LCSs to geomagnetic activity. The LCSs shift equatorward and eastward, developing a more complex topology in the apparent form of two cells in the northern hemisphere high latitude zone. We also show for the first time that the LCS demarcates the high-latitude boundary of shuttle plume observations after 48 hours of transport.