Investigation of Intermediate Layers in the Nighttime Ionosphere

Rebecca Bishop
University of Texas at Dallas

Intermediate layers are one of several phenomena that occur at midlatitudes in the nighttime E region. After forming on the bottomside of the F region, these plasma layers slowly descend to altitudes near 100 km where they may continue to exist for several hours. Layers are commonly observed by the Arecibo Incoherent Scatter Observatory (AO). We present AO observations that illustrate the dynamics and varying morphology of intermediate layers. Although the night-to-night occurrence of layers is likely the result of tidal winds, nightly variations may be the result of small scale wind field fluctuations, composition variations, and electric fields. To investigate the factors involved in local layer formation and evolution we have developed a numerical simulation named LEAD (Layer Evolution And Dynamics). In this talk, new results from LEAD are discussed and compared to intermediate layer observations by AO.