Production of the low-latitude night E layer

Abstract

A recent study of data from Arecibo concluded that the night E layer must consist primarily of metallic ions produced by meteors. Full model calculations show that this is not necessary. Known EUV sources (from starlight, scattered sunlight, and F region recombination) will produce an E region that agrees well with Arecibo results throughout the night. Direct rocket observations confirm that metallic ions are insignificant in the E region at all times. Model and data also agree on the absence of any appreciable changes with season or solar activity in the night values of NmE. The large solar cycle change in the IRI-95 model seems to come from an incorrect application of F region theory and should be deleted. Copyright 2001 by the American Geophysical Union.