The year 2008 marked a historically quiet period of solar activity during the declining phase of solar cycle 23. Such quiet time has permitted researchers to clearly distinguish the spectral signature of a corotating interaction region’s (CIR) impact on the open-closed boundary (OCB) of the magnetosphere in the southern hemisphere’s auroral zone. By using the PENGUIn AGOs network of ground-based magnetometers on the Antarctic continent, the synoptic behavior of the OCB during a CIR-driven magnetic storm has been studied. Observations were compared with results provided by the BATSRUS space weather model. It is shown that such synoptic magnetometer data sets of the OCB during these storms allows for a careful test of current space weather models.