Ascension and Port Stanley geomagnetic observatories and monitoring the South Atlantic Anomaly

Susan Macmillan, Chris Turbitt, Alan Thomson


Our 15-year experience of operating two remote observatories, Ascension and Port Stanley, in the south Atlantic
is described. These observatories help monitor the South Atlantic Anomaly (SAA), a region of weak magnetic
field which causes considerable problems for spacecraft operators. One-minute and one-second values from
these observatories, and other observatories both inside and outside the SAA, are analysed. We investigate
whether the SAA, and its growth over time, are having any tangible effect on the observed external field variations.
Whilst only able to illustrate the long-term characteristics of the irregular external field related to the solar
cycle and not due to any long-term changes in the internal field, we do isolate micropulsation signals at sites
inside the SAA which contain more power than at sites outside.


geomagnetism, observatories – South Atlantic Anomaly – secular variation – micropulsations

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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X