Overview:
• The crustal field Bcrust represents an offset error to the geomagnetic field vector from a global model
• Local magnetic observations are necessary to determine Bcrust and reduce errors
• Further improvement in estimates of B are possible with use of real-time magnetic data for external field Bexternal
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 and magnetosphere
− variations from seconds to years
Main Global Field Models Capture Some of the Crustal Field
• Novel weighting methods applied to satellite data
• Vector data at all latitudes
• Low-noise lithospheric field model
• Piecewise linear SV
• External dipole magnetic field with VMD index rapid timedependence
....
View the entire Presentation:
Using Local Observations of the Geomagnetic Field
Susan Macmillan - British Geological Survey