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 ob serve vertical ionospheric electron concentration profiles in the 80-2 80 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 wavelike 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 similar to 12 minutes appar ent period, normalized amplitudes of 1-3%, and vertical wavelengths 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.