Day-To-Day Variability of Total Content, Peak Density and Slab Thickness, and theIonospheric Response to Geomagnetic Storms

摘要

The issue of day-to-day ionospheric is of ongoing concern to users of satellites,navigation systems, and hf radio communications, and the mechanisms behind the variations are of interest to researchers. This report attempts to satisfy those operational concerns with a physical perspective, by analyzing hourly ionospheric data and developing an operationally useful model of the variations that is discussed in terms of the underlying physical processes. We describe an analysis of day-to-day variations in the total electron content, maximum electron density and equivalent slab thickness using nearly two solar cycles of observations from the American sector at mid latitudes. The report begins by quantifying day-to-day variability of these three F-region parameters and by performing a detailed correlation analysis between them. Usefulness of statistical and persistence forecasts are discussed. Then follows a study of the response of the ionosphere to geomagnetic storms, as these are the times when the variations from day to day are greatest. We then define storm patterns in terms of the departures on each day from average conditions in a storm-affected period. The average ionospheric response under a variety of conditions is described qualitatively and numerically. Individual storm patterns and common storm-related features are studied to characterize each storm and to investigate dependencies and interdependencies. The physical processes governing the observed responses and attempts to model these numerically, as well as applications to modeling real-time day-to-day variations in an operational sense, are discussed.