Ionospheric climatology and weather disturbances: A tutorial

Abstract

The ionosphere can have a detrimental effect on both civilian and military systems, including OTH radars, HF communications, surveillance, and navigation systems that use GPS satellites. In an attempt to mitigate the adverse effects, specification and forecast models are being developed that are based on sophisticated data assimilation techniques. However, the model development represents a significant challenge because the ionosphere is known to display a marked variation with altitude, latitude, longitude, universal time, season, solar cycle, and geomagnetic activity. This variation results from the couplings, time delays, and feedback mechanisms that are inherent in the system as well as from the effects of solar, interplanetary, magnetospheric, and mesospheric processes. The various processes act in concert to define both a background state (climatology) and a disturbed state (weather), which are described in this tutorial. First, a brief description of the background ionospheric state and the physical processes that are responsible for establishing this state is given. The tutorial then focuses on a discussion of weather disturbances and features, the causes of weather, and the status of weather modeling.