The composition and horizontal homogeneity of e region plasma layers

Abstract

A series of four NASA sounding rockets launched from Wallops Island, VA (37.84°N, 75.48°W), on 29-30 June 2003 between the hours of 23:19 and 3:07 EST observed an intermediate layer and a plasma density enhancement possibly associated with an internal gravity wave. Ion composition measurements were made by the third payload at 2:50 EST from 80- to 220-km altitude and included observations of three separate regions having high concentrations of metallic ions: a sporadic E layer at 105 km, an intermediate layer at 118 km, and the region above 160 km. The remaining payloads measured electron densities and made TMA chemical tracer releases at 23:19, 1:41, and 3:07 EST, respectively. This sequence of measurements shows that intermediate layers cannot be treated as flat layers over a scale of hundreds of kilometers and that internal gravity waves may lead to the formation of plasma layers in the nighttime lower F and upper E region ionosphere. The composition observations demonstrate that metallic ions may be a significant source of ionization in the nighttime E and F region ionosphere at midlatitudes, and that the relative ion composition within intermediate layers may fluctuate significantly over horizontal scales of hundreds of kilometers. Copyright 2007 by the American Geophysical Union.