Low and mid-frequency pulsations in the polar cap: polarization pattern and MLT dependence of the spectral power during the descending phase of the solar cycle

• Published in: Annals of Geophysics
• Main Authors: Umberto Villante, Massimo Vellante, Marcello De Lauretis, A. Piancatelli, Patrizia Francia
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2010
• Subjects: Geophysics; Geomagnetic Pole
• Online Access: https://www.openaccessrepository.it/record/130195; https://doi.org/10.4401/ag-4570

We present a statistical analysis of ULF (1-100 mHz) geomagnetic measurements conducted during years 2003-2006 at the Italian/French base of Concordia at Dome C, close to the geomagnetic pole, and at the Italian base«Mario Zucchelli» at Terra Nova Bay, also located in the polar cap, but at lower latitude. Our analysis shows thathigh latitude ULF pulsation power is largely controlled by the solar wind speed. At Terra Nova Bay the powershows a maximum at local noon, clearly related to cusp and closed field lines phenomena. At few mHz, the polarizationpattern indicates field line resonances driven, just equatorward with respect to the station, by wavespropagating tailward; the polarization of higher frequency pulsations, mostly originated from interplanetary upstreamwaves, suggests waves propagating sunward from the night sector. At Dome C the wave power shows asmall enhancement in the local morning, more pronounced for mid-frequency pulsations; the polarization pattern,at all frequencies, appears to indicate waves propagating sunward from the night sector, suggesting a propagationchannel to the ground via the magnetotail lobes.