Articles | Volume 35, issue 1
Ann. Geophys., 35, 139–146, 2017
Ann. Geophys., 35, 139–146, 2017

Regular paper 24 Jan 2017

Regular paper | 24 Jan 2017

A study of geomagnetic field variations along the 80° S geomagnetic parallel

Stefania Lepidi1, Lili Cafarella1, Patrizia Francia2, Andrea Piancatelli2, Manuela Pietrolungo1, Lucia Santarelli1, and Stefano Urbini1 Stefania Lepidi et al.
  • 1Istituto Nazionale di Geofisica e Vulcanologia, Rome, 00143, Italy
  • 2Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell'Aquila, L'Aquila, 67100, Italy

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.

Short summary
We study geomagnetic field variations from 1 min data at three Antarctic sites (Mario Zucchelli Station, Scott Base, Talos Dome) along the 80° S geomagnetic parallel. The daily variation depends on local time, due to the polar extension of midlatitude ionospheric currents. The ~1–7 mHz power maximizes around 12 MLT, close to the cusp, and the coherence does so between stations around 24 MLT. The wave propagation is consistent with a daytime solar wind source and with nighttime substorm processes.