Abstract
Use is made of an array of magnetic stations spread across the Australian mainland to examine the daily variation of the vertical element Z of the magnetic field. On sections of the west and east coasts visual inspection of Z variations shows that they respond mainly to the onshore component of the horizontal field as predicted by Bennett and Lilley, though only south of about 22°S on the east coast and south of 20°S on the west coast. On the north and south coasts this “coast effect” is not clearly seen at periods corresponding to the daily variation, though it sometimes appears on shorter time scales. On the north and south coasts Z appears to be mainly controlled by the decrease with latitude of the overhead eastward ionospheric currents as measured by the latitude gradient in the northward field, X. By subtracting the vector Z variation at an inland station from Z at a coastal station, the anomalous coastal effect in Z is calculated at periods of 12 and 24 h. These data show that the coastal effect is not just related to the horizontal onshore component but that some phase change is also required. An increase with latitude of the overhead eastward currents is sometimes found in morning hours corresponding to the morning current system identified in earlier work.
Article PDF
Similar content being viewed by others
References
Bennett, D. J. and F. E. M. Lilley, An array study of daily magnetic variations in southeast Australia, J. Geomagn. Geoelectr., 25, 39–62, 1973.
Chamalaun, F. H. and C. E. Barton, The large-scale electrical conductivity structure of Australia, J. Geomag. Geoelectr., 45, 1209–1212, 1993a.
Chamalaun, F. H. and C. E. Barton, Electromagnetic Induction in the Australian Crust: Results from the Australian-Wide Array of Geomagnetic Stations, Exploration Geophysics, 24, 179–186, 1993b.
Everett, J. E. and R. D. Hyndman, Geomagnetic variations and electrical conductivity structure in south-western Australia, Phys. Earth Planet. Interiors, 1, 24–34, 1967.
Gough, D. I., M. W. McElhinny, and F. E. M. Lilley, A magnetometer array study in Southern Australia, Geophys. J. R Astr. Soc., 36, 345–362, 1974.
Lilley, F. E. M. and R. L. Parker, Magnetic daily variations compared between the east and west coasts of Australia, Geophys. J. R. Astr. Soc., 44, 719–724, 1976.
Matsushita, S., Solar quiet and lunar daily variation fields, in Physics of Geomagnetic Phenomena, edited by S. Matsushita and W. H. Campbell, Academic Press, New York, 1967.
Parkinson, W. D. and F. W. Jones, The geomagnetic coast effect, Rev. Geophys. Space. Phys., 17, 1999–2015, 1979.
Srivastava, B. J., H. Abbas, T. RamaGopal, D. R. K. Rao, and B. M. Pathan, Geomagnetic coast and other effects deduced from the new observatory at Visakhapatnam, India, Geophys. J. Int., 146, 827, 832, 2001.
Stening, R. J. and P. A. Hopgood, Geomagnetic quiet daily variations in the Australian region—information from a new station at Charters Towers (20.1°S), J. Atmos. Terr. Phys., 53, 959–964, 1991.
Stening, R., T. Reztsova, D. Ivers, J. Turner, and D. Winch, Morning quiet-time ionospheric current reversal at mid to high latitudes, Annales Geophysicae, 23, 385–391, 2005a.
Stening, R., T. Reztsova, D. Ivers, J. Turner, and D. Winch, A critique of methods of determining the position of the focus of the Sq current system, J. Geophys. Res., 110, A04305, doi: 10.1029/2004JA010784, 2005b.
Whellams, J. M., Spatial inhomogeneity of geomagnetic fluctuation fields and their influence on high resolution aeromagnetic surveys, PhD thesis, Flinders University of South Australia, 1996.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Stening, R.J., Reztsova, T. The daily variations of the vertical (Z) element of the geomagnetic field around the coast of mainland Australia. Earth Planet Sp 59, 579–584 (2007). https://doi.org/10.1186/BF03352720
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1186/BF03352720