Observation of Electron Biteout Regions Below Twin Sporadic E layers at Arctic Latitude

In February 2009, four sounding rockets were launched from Poker Flat, Alaska to study the small scale dynamics of the turbopause region. A 10-km vertical wavelength long-period gravity wave dominantly modulated wind and temperature profiles. Here we focus on the effects of this wave on the electron density structure, specifically, two narrow Es layers near 94 and 102 km observed in situ and by incoherent scatter radar. The layers were visible in several radar beams and the lower one showed clear downward phase progression. They were located about 1 km above the maximum wind shear and at the zero zonal wind crossing. These data will allow the construction and evolution of the layers as modified by the background conditions. Below both layers, the in situ measurements indicated regions of electron biteout or depletion by an order of magnitude. The lower depletions coincide with the local temperature minima. The sodium lidar did not observe sporadic sodium layers during that time, and electron densities were below the threshold of the radar. We discuss the possibilities of neutral metal or dust layers that may have either caused real electron depletions or may have shifted the payload potential so that electron collection was less efficient. Temperature, electron density, and zonal wind speed from two consecutive rocket flights