This work presents the first simultaneous observations of Na and K between 120 and 150 km altitudes along with ionospheric tidal ion layers (TILs) obtained on 30 January 2006 data from Arecibo. The latter displays an average downward phase velocity of ∼14.7 ms-1. However, the neutral layers descend together at a much slower velocity of about ∼0.69 ms-1. This indicates that thermospheric atomic metal layers are not necessarily associated with TILs. The ratio of the average Na/K abundances in thermosphere is ∼35.5 as compared to 150 in the main layer (80-105 km). The long lifetimes of ions at ∼140 km implies that neutral layers cannot result from direct neutralization of metal ions in the TILs. We investigate different mechanisms that can deposit neutral atoms at thermospheric altitudes.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)