Data from over 100+ continuously operating GPS receivers in a
global network are being used
to produce global maps of the ionosphere's total electron content
(TEC). These Global Ionosphere Maps (GIM) provide instantaneous
"snapshots" of the global TEC distribution, by interpolating, in
both space and time, the 6-8 simultaneous TEC measurements obtained
from each GPS receiver every 30 seconds. The maps can be produced
unattended in a real-time mode, with an update rate of 5-15 minutes.
GIMs represent a new tool for monitoring global patterns of ionospheric
weather, a key component of the space weather, which is driven by changes
in solar ultra-violet radiation, the interplanetary particle stream known
as the solar wind, and the underlying composition, wind patterns and
electrodynamics of the thermosphere (the upper atmosphere at altitudes
between 100 and 1000 km). GIMs are being used for global ionospheric
delay calibrations, for scientific investigations of the upper
atmosphere, and will be an important data source for
the National Space Weather Program.
Monitoring Global Ionospheric Weather
