Fifty years ago, the first International Geophysical Year (IGY) generated a huge step function increase in observations of ionospheric variability associated with the almost continuous geomagnetic activity experienced during the largest solar maximum of the past 100 years. In turn, these observations fueled more than a decade of theoretical advancement of magnetospheric-ionospheric electrodynamics and geomagnetic storm physics.
In stark contrast, the current International Polar Year (IPY; 2007–2009) is occurring during what may well turn out to be the deepest solar minimum in 100 years. Potentially, it could be a very geomagnetically quiet period, a period during which ionospheric variability will be driven by processes in the troposphere and mesosphere. Since the variability of the ionosphere-thermosphere system associated with the upward propagating planetary, tidal, and gravity waves from the lower atmosphere is expected to be independent of the solar cycle, the IPY period is an ideal time to study the interchanges between the lower and upper atmospheric regions.