Low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

Abstract

We present a statistical analysis of low frequency (~0.5-5 mHz, periods ~3-30 min) geomagnetic field fluctuations at the Antarctic stations Mario Zucchelli Station (TNB, formerly Terra Nova Bay) and Scott Base (SBA), which are located at the same geomagnetic latitude but with 1-hr difference in MLT (Table 1). The two stations are usually in the polar cap, at the footprint of open geomagnetic field lines, but around local geomagnetic noon they approach the polar cusp. This study focuses on the coherence and phase difference between the fluctuations at the two stations. The analysis is based on 1-min values of the horizontal H component measured during the entire years 2001-2002. The coherence and phase difference have been computed for each 2-hours interval with a step-size of 1 hour. Station TNB is run by INGV; data from SBA are provided by INTERMAGNET CD-ROMs. Interplanetary magnetic field (IMF) and solar wind (SW) data from ACE spacecraft have been downloaded from OMNI database. Interplanetary data have been delayed by 1 hour to take into account the average SW transit time from ACE to Earth.