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Authors: Pietrolungo, M.* 
Lepidi, S.* 
Cafarella, L.* 
Di Mauro, D.* 
Title: A statistical analysis of low frequency geomagnetic field pulsations at two Antarctic geomagnetic observatories in the polar cap region
Journal: Advances in space research 
Series/Report no.: /52 (2013)
Publisher: Elsevier Science Limited
Issue Date: 2-May-2013
DOI: 10.1016/j.asr.2013.05.001
Keywords: Solar wind-magnetosphere interactions; Polar cap phenomena; MHD waves and instabilities
Subject Classification01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics 
Abstract: The aim of this study is to investigate the characteristics of low frequency ( 0.5–5 mHz) geomagnetic field fluctuations as recorded at two Antarctic stations within the polar cap: the Italian observatory Mario Zucchelli Station (TNB) and the French–Italian observatory Dome C (DMC) in order to investigate the spatial extension and propagation characteristics of the phenomena observed at very high latitude. The stations have approximately the same geographic latitude, but a very different corrected geomagnetic latitude, being DMC close to the geomagnetic pole and TNB closer to the auroral oval. Our study focused on power spectra, coherence and phase difference between low frequency fluctuations analyzing the horizontal H component measured during the entire year 2006. The fluctuation power behavior during the day can be explained according to the positions of the stations with respect to the polar cap; indeed in the dayside sector it is higher in the cusp region, while in the nightside sector it is higher close to the geomagnetic pole. Furthermore the study of coherent fluctuations, focusing on their phase difference, indicated that the propagation direction within the cap is variable during the day: in the dayside and nightside regions it is from the auroral oval toward the geomagnetic pole, while in the magnetic local morning and afternoon sectors it is from the geomagnetic pole toward the dawn–dusk meridian. Finally the analysis of two individual pulsation events, consisting of short duration wave packets, is shown; it confirms the statistical considerations on the propagation direction and allows to estimate the wave number and apparent phase velocity, whose values are of the order of 3–4 and 30–15 km/s, respectively.
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