Aspects of layer electrodynamics inferred from high-resolution ISR observations of the 80-270 km ionosphere

The Arecibo 430 MHz Incoherent Scatter Radar (ISR) has been used to observe vertical ionospheric electron concentration profiles in the 80-280 km altitude region at the highest sustained resolutions (150 m, 10 s) thus far reported for "ion-line" measurements. We present results that reveal layers and wave-like features in unprecedented detail and likely point to electrodynamic processes linking the E and F regions. Tidal Ion Layers (TILs) and sporadic E (E_s) layers in the 100-110 km altitude region often display significant peaks and edges that appear in only one range gate (150 m). Also, previously unreported wave-like plasma structures - termed "ion rain" - with ∼12 minutes apparent period, normalized amplitudes of 1-3%, and vertical wave-lengths in excess of 30 km have been observed extending from base of the F-layer to the evening intermediate TIL with indications of coupling into the 90-110 km region below.