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An analysis of the geomagnetic diurnal variation during the International Geophysical Year

Created 16/10/2025

Updated 16/10/2025

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A spherical harmonic analysis has been made of the quiet-day diurnal variation of the geogmagnetic field during the IGY, based on mean hourly values from 64 observatories. Each of the 18 months has been analysed separately, and the coefficients have been averaged over each of four seasons. Fourier coefficients were expressed as functions of latitude and longitude by the Gram-Schmidt method, and non-significant coefficients of the orthogonal functions were discarded. The dependence on longitude was restricted so that only smooth departures from the local time dependence were allowed. The potential was derived by averaging that found from the east and north components. External and internal potentials were derived from the surface potential and vertical component. Ratios of, and phase differences between, the external and internal potentials were derived for each harmonic. They were also computed as functions of latitude and longitude, but no significant geographical distribution was found. The ratios and phase differences generally agree fairly well with those derived from earlier analyses. The amplitudes of the harmonics are generally about twice as great as those derived by Chapman for the 1905 data. This is probably because 1957 and 1958 were years of very high sunspot number. Tables of coefficients and maps of the elements and current functions are given.

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Field Value
Title An analysis of the geomagnetic diurnal variation during the International Geophysical Year
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/79df3064-9d56-4e07-8b22-049548077b1f
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage Australia
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "An analysis of the geomagnetic diurnal variation during the International Geophysical Year". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/an-analysis-of-the-geomagnetic-diurnal-variation-during-the-international-geophysical-year