Geoscience Reference
In-Depth Information
Antarctica provides important additional spatial information on space phenomena
as mapped to Earth
'
s surface. Of course, a similar situation exists in the northern
hemisphere, but there is no land mass coverage across the North Pole for installing
arrays of instruments.
A research problem of high signi
cally as well as for more
practical applications, is the state of the electrical currents in the ionosphere.
These can be monitored across the Antarctic continent, and thus across many
geomagnetic latitudes, through the employment of magnetometers at the manned
stations of many nations as well as at many unmanned locations, such as those of
the Automatic Geophysical Observatories of the United States and similar sites
maintained by the United Kingdom and Japan. Combining these many
magnetometer data sets and inverting them to produce ionosphere equivalent
electrical currents yields maps of the spatial distributions of the currents and
their changes with time.
These inferred ionosphere currents over the Antarctic continent can be
cance, both scienti
'
field lines for comparison with similar currents inferred
from northern hemisphere measurements. Such mapping provides unique
information on the global nature of Earth
mapped
'
along magnetic
s ionosphere in polar regions as well as
on the properties of the space environment at large distances from Earth (since
the magnetic
'
to near the edges of the magnetosphere).
Another technique for measuring different aspects of the high latitude ionosphere
uses spaced arrays of the order of six to eight radars (called SuperDARN radars)
in both hemispheres. These radars measure the conditions of ionosphere plasmas
and the measurements in the Antarctic can be again mapped into the northern
hemisphere for inter-hemisphere comparisons and for high latitude global views
of Earth
field lines
'
map
'
s space environment.
Other instrumentation is also used at many of the magnetometer sites for
measurements of other solar
'
terrestrial phenomena. For example, optical imaging
systems at many sites are used during austral night-time conditions to map the
changes in the aurora. These measurements are important in that it is not possible to
get such widely spaced measurements of the aurora from the northern hemisphere,
and certainly not at such high geomagnetic latitudes. And in conjunction with
magnetometer and radar data, much more information on the state of the space
environment is thereby obtained.
With so few people in the Antarctic, the radio quiet environment means that
radio waves over a wide frequency range can be measured and monitored as a
function of geomagnetic conditions and also in association with other measurements
of the space phenomena. In particular, measures of radio waves at Very Low
Frequencies (VLF; 3
-
30 kHz) are associated with important processes in the
magnetosphere that can produce the loss of radiation belt particles. These
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