ALBERT

Description: After a short survey of the ionospheric observations made during the expedition special experiments on and near the geomagnetic equator are described. Using the mobility of the ship together with the form of the antenna pattern the structure of the equatorial Es -layer (Esq) was investigated. It was shown that the Esq-layer contains a filamentary structure which is orientated along the magnetic field lines of the earth. Further polarisation experiments were made in order to investigate the attenuation or blanketing of either the ordinary or the extraordinary component of a magneto-ionic wave. This attenuation and blanketing of the components can be observed conveniently in the vicinity of the geomagnetic equator since the polarisations of both components are linear in this region. Our measurements have shown that during daytime the directions of maximum suppression for the ordinary and the extraordinary component were not exactly perpendicular to each other but deviated from orthogonality by a small angle. This effect was interpreted as an influence of electron collisions on the polarization in the lower ionosphere. Finally a special 2 · F-propagation mode was found in performing these polarisation experiments. In this mode one hop: ground - ionosphere - ground is passed as an ordinary wave, the other as an extraordinary wave. Such a mode can exist only when a coupling between the two gyromagnetic waves is present. An example is shown in which the coupling is possibly caused by two different effects, namely 1. the gyromagnetic components are not perpendicular to each other in the lower ionosphere and 2. the filaments in the Esq-layer act as depolarizers.