Modelling Secular Variation in the Southwest Pacific

Main Article Content

Maha Ali Alfheid
Mohana Faroug Attia


A spherical cap harmonic analysis (SCHA) model has been used to derive a high resolution regional model of the geomagnetic field in the southwest Pacific region over the past 400 years. Two different methods, a self-consistent and the gufm1 dipole method, have been used to fill in gaps in the available data. The data used in the analysis were largely measurements of the magnetic field recorded in ships logs on voyages of exploration in the region.  The method chosen for the investigation used a spherical cap of radius

Southwest pacific, geomagnetic field, gufm1, spherical harmonic analysis.

Article Details

How to Cite
Alfheid, M. A., & Attia, M. F. (2019). Modelling Secular Variation in the Southwest Pacific. Asian Journal of Advanced Research and Reports, 6(2), 1-20.
Original Research Article


Matts DC. The theory of magnetism: An introduction to the study of cooperative phenomena: Harper & Row; 1965.

Merrill RT, McElhinny MW, McFadden PL. The magnetic field of the earth: Paleomagnetism, the core and the deep mantle: Academic Press; 1998.

Parkinson WD. Introduction to geomagnetism. Scottish Academic Press; 1983.

Bloxham J, Gubbins D. The secular variation of Earth's magnetic field. Nature. 1985;317:777-781.

Haines GV. Spherical cap harmonic analysis. Journal of Geophysical Research. 1985;90:2583-2591

Alldredge LR. Varying geomagnetic anomalies and secular variation. Journal of Geophysical Research: Solid Earth. 1983; 88(B11):9443-9451. Available:https://10.1029/JB088iB11p09443

Jackson A, Jonkers AR, Walker MR. Four centuries of geomagnetic secular variation from historical records. Philosophical Transactions: Mathematical, Physical and Engineering Sciences. 2000;358(1768): 957-990. Avialable:https://10.1098/rsta.2000.0569

Blakely RJ. Potential theory in gravity and magnetic applications. Cambridge: Cambridge University Press; 1996.

Torta JM, Gaya-Piqu ÉL, De Santis A. Spherical cap harmonic analysis of the geomagnetic field with application for aeronautical mapping. In J. Rasson & T. Delipetrov (Eds.), Geomagnetics for Aeronautical Safety: Springer Netherlands. 2006;291-307.

Korte M, Haak V. Modelling European magnetic repeat station and survey data by SCHA in search of time-varying anomalies. Physics of the Earth and Planetary Interiors. 2000;122(3):205-220.

Hwang C, Chen SK. Fully normalized spherical cap harmonics: application to the analysis of sea-level data from TOPEX/ POSEIDON and ERS-1. Geophysical Journal International. 1997;129(2):450-460.

Ingham. The geomagnetic field in the south pacific during the 19th century New Zealand: Victoria University of wellington; 2009.

Jonkers AR, Walker MR. Four centuries of geomagnetic secular variation from historical records. Philosophical Transactions: Mathematical, Physical and Engineering Sciences. 2000;358(1768): 957-990. Available:https://10.1098/rsta.2000.0569

Gubbins D. Can the Earth's magnetic field be sustained by core oscillations? Geo-physical Research Letters. 1975;2(9): 409-412. Available:https://10.1029/GL002i009p00409

Turner G. North Pole, South Pole: The epic quest to understand the great mystery of the Earth's magnetism / Gillian Turner. Wellington, N.Z: Awa Press; 2010.

Lilley FEM, Day AA. D'Entrecasteaux, 1792: Celebrating a bicentennial in geomagnetism. Eos, Transactions American Geophysical Union. 1993;74(9): 97-103. Available:https://10.1029/93EO00168

Sabine E. Report on the variations of the magnetic intensity observed at different points of the earth's surface: Richard and John E. Taylor; 1838.

De Labillardière JJH. Voyage in search of La Pérouse: John Stockdale; 1800.

Bemmelen V. Abel Janszoon Tasman's Journal of his discovery of Van Diemen's Land and New Zealand in 1642: With documents relating to his exploration of Australia in 1644: being photo-lithographic facsimiles of the original manuscript: With an English translation to which are added Life and labours of Abel. By J.E. Heeres and Observations made with the compass by. Amsterdam: Frederik Muller; 1898.

Barton C, McElhinny M. A 10 000 yr. geomagnetic secular variation record from three Australian maars. Geophysical Journal International. 1981;67(2):465-485.

Turner GM, Lillis DA. A palaeomagnetic secular variation record for New Zealand during the past 2500 years. Physics of the Earth and Planetary Interiors. 1994; 83(3–4):265-282.