Skip to Content | Contact

Signatures of distorted geomagnetic field lines in Antarctic magnetometer data

Signatures of distorted geomagnetic field lines in Antarctic magnetometer data
Sean Ables

Authors

Ables S
The University of Newcastle

Sciffer M
The University of Newcastle

Waters C
The University of Newcastle

Inness E
Institution not provided

Fraser B
The University of Newcastle

Abstract

Ultra-low frequency (ULF) wave signatures in the magnetometer data from Davis, Antarctica (74.49° S, 100.03° E CGM) often exhibit spectral characteristics which can be interpreted as field line resonances (FLR) of the outermost closed field lines in the dayside magnetosphere. Diurnal variations in the frequency at which maximum power occurs in the Pc5 (1-10 MHz) band, often show an arch-shaped variation with local magnetic time. The general topology of the dayside high latitude magnetosphere results in longer field lines and therefore lower resonance frequencies on the dawn and dusk flanks, and the shortest field lines and higher resonant frequency for field lines near magnetic noon, passing through the sub-solar point. Similar FLR variations are seen in magnetometer data from the Mawson, Casey and Scott Base, Antarctica. We present an eigenfunction solution for shear Alfvén waves which also accounts for the curvature and torsion of the magnetic field that threads high latitude stations. This provides an explanation for our observations of a saddle in the Pc5 arch - a decrease in frequency centred on local magnetic noon - which is seen in Davis magnetometer data and to a lesser extent in Mawson, Casey and Scott Base data. Our modelling indicates that this saddle is due to increased field torsion on the dawn and dusk flanks producing increased pre- and post noon frequencies while the noon frequencies are depressed by field curvature.

Latest news

  • Conference prize winners
    27 Jun 2013

    The Strategic Science in Antarctica conference concluded yesterday and two days of workshops have commenced. Congratulations to those who were awarded prizes for their contributions to the conference.

  • Watch the welcome message from Australia's Environment Minister
    24 Jun 2013

    In a welcome message via video from Canberra, Australia’s Environment Minister, Tony Burke, reflected on the foresight of earlier decision-makers who agreed to set aside an entire continent for scientific research.

  • Last minute information for attendees
    20 Jun 2013

    There's not too long to wait until the start of the Strategic Science in Antarctica conference, and we hope you’re as excited as we are! Read on for more information about the final program, registration, Twitter, presenters, posters and social functions.

More news…

Key dates

  • 11th June 2013
    Registrations close
  • 21st June 2013
    Registrations at the AAD open for staff
  • 24th June 2013
    Registrations at the venue open
  • 24th June 2013
    Conference commences
  • 26th June 2013
    Conference concludes

More key dates…

This page was last modified on 3 September 2013.