Application of the coded long‐pulse technique to plasma line studies of the ionosphere

Abstract

Recently, the coded long‐pulse radar technique was tested at Arecibo Observatory, Puerto Rico using photoelectron‐enhanced plasma lines in the daytime ionosphere. The technique immediately proved to be a powerful diagnostic tool for studying natural ionospheric phenomena. Our initial observations indicate that extremely accurate measurements of absolute electron density (0.01 to 0.03% error bars) can be achieved with an altitude resolution of 150 m and a temporal resolution of ∼2 s. In addition, the technique provides information about electron density structure within a 150‐m altitude cell and yields parameters from which the energy spectrum of suprathermal electrons (≥ 5 eV) can be deduced. Our earliest measurements are used to illustrate applications of the coded long‐pulse technique to several aeronomic/ionospheric areas of current interest. These include studies of neutral wave motions in the lower thermosphere, measurements of ion composition in the F1 region/upper ionosphere, and investigations of electron‐gas thermal balance and photoelectron energy loss processes. The technique can be utilized to examine irregularity formation in the F region, probe electron acceleration processes in ionospheric modification experiments, verify the magnetic field dependence of Langmuir wave damping, and more generally test higher order corrections suggested for the Langmuir dispersion relation. It is anticipated that the latter tests will facilitate measurements of ionospheric currents.

High‐resolution studies of atmosphere‐ionosphere coupling at Arecibo Observatory, Puerto Rico

“…2Arecibo Observatory, Arecibo, Puerto Rico. incoherent scatter radar at Arecibo, Puerto Rico, are described by Djuth et al [1994] who also include a discussion of the advantages and limitations of the methodology. In the study presented here, the CLP-PEPL technique is employed to examine neutral wave motion in the lower thermosphere.…”

“…Very accurate measurements of electron density can be made at Arecibo Observatory, Puerto Rico, by applying the coded long-pulse (CLP) radar tectmique [Sulzer, 1986a] to plasma line echoes from daytime photoelectrons [Djuth et al, 1994]. In the lower thermosphere above Arecibo, background neutral waves couple to the ionospheric plasma, typically yielding ~1-3% electron density "imprints" of the waves.…”

Lag profile inversion method for EISCAT data analysis

“…This method has been used in several special experiments including plasma line studies (Djuth et al, 1990(Djuth et al, , 1994, interferometric measurements (Grydeland et al, 2005a(Grydeland et al, ,b, 2004, and references therein), observations of meteor-head echoes (Chau and Woodman, 2004;Sulzer, 2004) and for lag profile analysis Damtie et al, 2002). The MIDAS-W system in Millstone Hill is also capable in recording the raw data (Holt Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Plasma line observations from the EISCAT Svalbard Radar during the International Polar Year

“…Vierinen et al (2016) used the plasma line measurements from the Sondrestrom incoherent scatter radar to determine plasma density profiles at very high temporal resolution in order to study the variability of the energy and flux of the electron precipitation. A coded long-pulse plasma line technique for incoherent scatter radars has been developed to obtain measurements of the plasma line at very high range and time resolution, and its strength was demonstrated in a study of small density fluctuations in the ionosphere caused by gravity waves (Djuth et al, 1994(Djuth et al, , 1997.…”