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

Abstract

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

Keywords

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