An attempt for objective analysis of TIROS-N images

An attempt for digital processing of analog images taken in the infrared channel (10.5–11.5 μm) from TIROS-N is presented. The data digitized to 8-bits are normalized by using SR Data Manipulator. The investigated period is November 3–4, 1979. The geographic rectification moves the data into a polar stereographic map. To estimate the cloud heights empirical relationships are applied. The following characteristics of the cloud field are produced: the cloud amount, the dominant cloud-type, the daily variation of IR brightness temperature and the cloud texture. The results are visualized on a colour display.     

Model calculations of middle atmospheric wind and temperature fields

The zonally-averaged circulation of the middle atmosphere between 10 and 110 km is calculated from a two-dimensional grid point model for steady solstice conditions. Using the temperatures of CIRA 72 in a diagnostic study of the vertical-meridional circulation we have investigated the influence of a latitude dependent static stability and the consequences of meridional temperature advection. In the summer mesopause region we found an area of subsidence which is located near the equatorward boundary of the noctilucent cloud region. In a self-consistent dynamical study we have assumed an empirical momentum source in the lower summer thermosphere in addition to the well-known Rayleigh friction to obtain an eastward zonal flow in this region.     

Large-scale electric fields and currents and related geomagnetic variations in the quiet plasmasphere

At the end of the sixties it became obvious that two-dimensional dynamo models can explain nearly all facts, which had been found morphologically for mean annual Sq-fields. During the recent decade new or improved methods to measure electric fields (e.g. incoherent scatter facilities) and to investigate great data files have been developed. New informations received with these methods about the existence of regular variations of the Sq-field in dependence on season and universal time and about the electric field have been summarized in Section 2. All attempts to describe also these variations with a two-dimensional dynamo model did not lead to any success, but showed a strong theoretical over-estimation of the asymmetries. Therefore, it must be concluded that three-dimensional plasmaspheric current systems, taking into consideration the coupling between both hemispheres along the high-conducting magnetic field lines, are needed in order to explain the regular variations of the Sq -field. The basic equations for two- and three-dimensional dynamo models, different methods for the solution of these equations and the resulting models from different authors are compiled and discussed (Section 3).Based on all morphological and theoretical results a plasmaspheric-ionospheric current system has been constructed and some properties of the plasmaspheric field-aligned current distribution, have been derived.