Thomson scatter radar detection of D‐region negative ions at Arecibo

Abstract

The Arecibo 430 MHz radar has been used to measure D region Thomson scatter power spectra which display bandwidth and power variations with altitude and solar zenith angle which are consistent with the presence of negative ions. The negative ion‐to‐electron number density ratio (λ − ), electron density, and electron‐to‐ion temperature ratio (T e /T i ) have been derived from the spectral data and presented for noontime and sunset conditions. The λ − = 1 level is found to occur near 70 km at noon and near 80 km at sunset. Values of T e /T i in the range 1.0 to 1.5, due to probing pulse heating, were observed.