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European Repeat Station Workshop Bucharest May 2007 UK repeat station programme Tom Shanahan and Susan Macmillan.

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Presentation on theme: "European Repeat Station Workshop Bucharest May 2007 UK repeat station programme Tom Shanahan and Susan Macmillan."— Presentation transcript:

1 European Repeat Station Workshop Bucharest May 2007 UK repeat station programme Tom Shanahan and Susan Macmillan

2 European Repeat Station Workshop Bucharest May 2007 The Earth’s magnetic field Most of the field is from the Earth’s core  varies slowly with time (months to years) Local fields from magnetized rocks in Earth’s crust  relatively stable with time Fields due to currents in the ionosphere (from about 100 km altitude) and the magnetosphere (several earth radii)  variations from seconds to years Repeat station observation and reduction programmes aimed at monitoring the core field but they also include the crustal field

3 European Repeat Station Workshop Bucharest May 2007 Regional model - provides magnetic north data for 200 topographic and 30 geological maps in UK every year

4 European Repeat Station Workshop Bucharest May 2007 Grid Magnetic Angle convergence = difference between true north and grid north declination - convergence = grid magnetic angle

5 European Repeat Station Workshop Bucharest May 2007 Regional model

6 European Repeat Station Workshop Bucharest May 2007 Rate of change does change!

7 European Repeat Station Workshop Bucharest May 2007 Regional model declination residuals

8 European Repeat Station Workshop Bucharest May 2007 UK crustal field from aeromagnetic & marine surveys

9 European Repeat Station Workshop Bucharest May 2007 Other work done with the UK repeat station data inducing field changed by almost 20° Jackson, A., Study of crustal magnetic anomalies of the British Isles, Astronomy and Geophysics 48(2): an attempt to separate induced and remanent magnetisation using dense repeat station data collected in and airborne surveys done in


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