Solar activity such as flares and coronal mass ejections often produce large
variations in the particle and electromagnetic radiation incident upon the
earth. Such variations can, in turn, lead to disturbances of the "quiet-time"
magnetosphere and ionosphere. These disturbances, when affecting the
ionosphere are known as ionospheric storms, tend to generate large
disturbances in ionospheric density distribution, total electron content,
and the ionospheric current system. Ionospheric storms have important
terrestrial consequences such as disrupting satellite communications and
interrupting the flow of electrical energy over power grids. They also
provide the most challenging conditions under which accurate assessment of
the vertical delay calibrations, to be used
in the WAAS aircraft navigation system, must be
maintained. Thus, it is important to monitor such storms, and, if possible,
forecast their evolution.
The ability to use the global GPS network
to generate global maps
of the ionosphere's total electron content (TEC) in
near real-time presents us with a new and powerful tool for not only
detecting ionospheric storms and monitoring their behavior, but also
for pursuing scientific research that will lead to a more complete
understanding of storm phenomena. A differential mapping technique
(DMT) has been developed, which makes it possible to identify,
characterize, and classify storms by distinguishing storm-time
variations of the ionosphere from quiet-time variations. What is
unprecedented in this approach is the ability to study ionospheric
storms on simultaneous world-wide scales in near real-time.
Monitoring Global Ionospheric Weather
