Signatures of the ULF geomagnetic activity in the surface air temperature in Antarctica

Abstract

The variations of the Pc5 and Pc1-2 ULF power and surface air temperature measured at Terra Nova Bay in Antarctica have been analyzed during the late declining phase of solar cycle 23 (2007–2008), in comparison with the simultaneous variations of the solar wind speed. The analysis focused on time scales of several days, which characterize the evolution of the solar wind stream structure. The temperature variations appear clearly during the local winters, while they are strongly reduced in the sunlit summers. During the local winters, the Pc5 and Pc1-2 power and the temperature variations are significantly correlated, with the temperature delayed by a few days with respect to the ULF power. A time-frequency analysis revealed common signals in the temperature and ULF power at periodicities related to the Sun’s rotation period (~27, 13.5, and 9 days), which, in the same time intervals, characterize the solar wind speed and geomagnetic activity.