Tom Beer

Equatorial F region motions deduced from Sq currents

It is possible to deduce F region ionization motions from Sq current distribution maps, but it is known that the agreement between the deduced velocities and the experimentally observed velocities is poor. In order to determine whether the disagreement between the deduced and the observed results is a result of the uncertainty in the location of the zero value of the current the velocities were deduced from an Sq map with the daily mean values as the base line and from an Sq map with the midnight values as the base line. The disagreement between the deduced and the observed velocities in both cases indicates the importance of polarization fields in ionospheric motions.

Atmospheric waves and the ionosphere

Abstract The earths atmosphere is a fluid that is capable of supporting wave motions whose amplitudes grow with height. This article reviews some of the evidence for the existence of these waves and outlines a simple theoretical approtioh for describing them. Finally, the article reviews the studies that have been made dealing with the interaction between the ionization and the atmospheric waves believed to exist at ionospheric heights—namely accoustic waves, evanescent waves and inter-nal atmospheric gravity waves.

Atmospheric waves and the equatorial ionosphere

Abstract Rotational effects due to the meridional gradient of the Coriolis parameter produce a class of equatorial gravity waves whose dispersion properties resemble those of acoustic waves. Supersonic sources near the equator should then be able to excite these equatorial waves. Rotational effects at mid-latitudes may also be responsible for the paucity of equatorial TID observations.

The dispersion of thermospheric waves

Abstract It is shown that the dispersion of F -region ionization irregularities can be described in terms of atmospheric waves, provided that there is some form of impedance matching between the wave and its source. Analysing the dispersion curve enables one to determine the altitude of atmospheric wave generation, and to identify possible source mechanisms.

Equatorial total electron content fluctuations due to atmospheric waves

Abstract Theory predicts that only those atmospheric wave fluctuations appear on TEC records whose crests and troughs lie along the line of sight from observer to satellite. This should produce a narrow range of observable periods but it is difficult to confirm this finding with observational data.

The equatorial ionosphere

Abstract At the magnetic equator the Earths magnetic field is completely horizontal. This provides a constraint on the motion of the charged particles that comprise the ionosphere and produces dis...