Ionospheric electron content and space weather: Some examples

Abstract Space Weather effects influence the atmosphere of the Earth, among others stratospheric ozone. One other region of the upper atmosphere which shows very strong Space Weather dependence is the ionosphere. It is a very important region because it affects satellite communication and navigation. On the other hand the ionization is a good tracer and indicator for various Space Weather influences. In this respect the ionosphere has no predictive capabilities and cannot support early warning but it provides one link between the sun, the solar wind, the magnetosphere and the neutral atmosphere. Solar EUV induced inospheric effects are coupled to solar radiation related events in the neutral atmosphere and therefore ionospheric effects give some qualitative hints at possible effects on stratospheric ozone. Ionospheric Space Weather effects can be observed continously from the ground by means of propagation effects on radio waves. Electron content (TEC) is a very important descriptive quantity for the ionosphere of the Earth. TEC is gained by means of “propagation effects” which are observed on received radio signals which are transmitted from artificial satellites. TEC data have been collected in Europe systematically and on a longterm basis since 1965. The data are used to investigate “geophysical events”, e.g., the Space Weather related (magnetic) storm effects. They are also used to formulate empirical models which describe the large scale and longterm behaviour of average TEC data, usually of monthly medians. We show examples for “instantaneous” TEC data, for a monthly median TEC model and for TEC maps produced on a regular basis for application purposes.