Abstract
Abstract. The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007–2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ∼ 1–7 mHz). We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.
Highlights
Geomagnetic field measurements in Antarctica are valuable for the study of magnetospheric dynamics and dynamic processes controlling the energy transfer from the solar wind (SW) to the Earth’s magnetosphere in that local field lines reach extreme magnetospheric regions where this interaction occurs
A comparison of the daily variation at Scott Base (SBA), TNB and Talos Dome (TLD) is shown in Fig. 4, which reports the daily distribution of the average 10 min values of the two horizontal geomagnetic field components at the three stations; in addition to the H –D horizontal components ordered according to magnetic local time (MLT), for this analysis we show data rotated into the geographically oriented reference system, i.e., the X and Y geomagnetic field components ordered according to local time (LT)
During the 2007–2008 Antarctic campaign, we installed a magnetometer at Talos Dome (TLD), a new observation site in Antarctica to extend the observation facilities in the southern polar cap
Summary
Geomagnetic field measurements in Antarctica are valuable for the study of magnetospheric dynamics and dynamic processes controlling the energy transfer from the solar wind (SW) to the Earth’s magnetosphere in that local field lines reach extreme magnetospheric regions where this interaction occurs. The global distribution of geomagnetic observatories is still quite unbalanced in favor of the Northern Hemisphere; in this sense, the installation of a magnetometer in a new observation site in the Antarctic continent is useful in the study of the magnetospheric dynamics at high latitudes For this reason, during the 2007–2008 Antarctic campaign, we installed a low-power magnetometer (LPM) at Talos Dome (TLD), within the framework of the AIMNet (Antarctic International Magnetometer Network) project, proposed and coordinated by the British Antarctic Survey and joined by the Italian Programma Nazionale Ricerche in Antartide (PNRA). SBA, TNB and TLD are at approximately 2 h total displacement in magnetic local time (MLT; see Table 1 and Fig. 1) This location is useful for investigating the azimuthal signal distribution and propagation. In this study we show a comparative analysis of geomagnetic field horizontal components recorded at TLD, TNB and SBA from 18 January to 14 March 2008, focusing attention on the daily variation and low-frequency pulsations at the three sites
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