Fig. 8.
From: Testing IGRF-11 candidate models against CHAMP data and quasi-definitive observatory data
Means and standard deviations (represented as error bars) of the differences (in nT/yr) between the observed and predicted secular variations at the 86 selected observatories producing definitive data (Test (2)), calculated for the Y (left) and Z (right) components. At each observatory, the observed secular variation is obtained by averaging annual differences over three different time intervals: June 2008 (no averaging; top), March to June 2008 (middle), and July 2007 to June 2008 (down).