Robert Pfaff, NASA/Goddard Space Flight

Title: Upheavals in the Ionosphere -- Tracking Down the Causes of Expansive Plasma Depletions  (Video)

Abstract: The ionized gas in the earth’s upper atmosphere is known, at times, to become abruptly unstable, turbulent, and highly unpredictable at low latitudes after sunset.  This natural behaviour of our geospace environment results in large scale, inter-hemispherical plasma depletions that can rise to altitudes of over 1000 km, spawning shorter scale irregularities and turbulence that wreck havoc on communication and navigational signals such as GPS.  After decades of concerted research, experimental physicists, theorists, and modellers are converging at the core mechanisms responsible for these large scale fissures in geospace and their associated instabilities.  In particular, measurements of electric fields and plasma number density gathered by probes on satellites and sounding rockets in the ionosphere, as well as detailed observations with high-powered radars, have revealed evidence for shears and differential flows between the ion and neutral gas populations that are believed to create the seeds for these large scale disruptions.  We present recent experimental evidence that is at the root of this long-standing mystery of space geophysics, while also shining light on important intrinsic properties of partially ionized gases in space.