Quinn et al. This article provides the algorithm for computing the values of the reference field from the IGRF model and secular variation values. Spatial and attribute information. The resulting data set was converted to shapefile format. Lines indicating equal annual change in the total field intensity of the Earth's magnetic field.
Magnetic intensity is the strength of the magnetic field.
The representation of the entity in the data. Internal sequence number of the from-node. Internal sequence number of the to-node. Internal sequence number of the left polygon. Internal sequence number of the right polygon.