Answer: Both
satellites and ground-based magnetometers are important for making measurements
of the Earth’s magnetic field. They are not redundant, but are,
instead, complementary. After executing several orbits of the Earth, satellites
can provide good geographical coverage for data collection. On the other
hand, ground-based magnetometers are much less expensive than satellites,
they are much easier to install and control than satellites, and, with
an array of magnetometers, they can provide coverage from numerous locations
simultaneously. Another
consideration is that satellites orbit the Earth either inside or above
the ionosphere, the electrically conducting part of the Earth’s
atmosphere. Since currents in the ionosphere contribute to the magnetic
field, this means that the field measured by a satellite is somewhat different
than the field measured at the surface. Finally, don’t forget that
it is at the surface of the Earth, where we live, that many of the effects
of space weather are most important, so measurements from ground-based
observatories will always play a critical role in space-weather studies. |
