Trajectories of thermospheric air parcels flowing over Alaska, reconstructed from ground‐based wind measurements

摘要: It is widely presumed that the convective stability and enormous kinematic viscosity of Earth's upper thermosphere hinders development both horizontal vertical wind shears other gradients. Any strong local structure (over scale sizes several hundreds kilometers) might somehow form would be expected to dissipate rapidly. Air flow in such an atmosphere should relatively simple transport effects only slowly disperse mix air masses. However, our observations show fields have much more local-scale than usually predicated by current modeling techniques, at least auroral latitudes; they complicate parcel trajectories enormously, relative typical expectations. For tracing parcels, we used measurements all-sky Scanning Doppler Fabry-Perot interferometer reconstructed time-resolved two-dimensional maps vector field infer forward backward over time. This first comprehensive study visualize complex motions thermospheric parcels carried through actual observed structures high-latitude winds. Results a very difficult observational problem, because followed are sensitive detailed features driving field. To reconstruct motion given requires everywhere along trajectory followed, with spatial resolutions 100 km or less, temporal few minutes better. Understanding important, for example predicting global-scale impacts aurorally generated composition perturbations.