Fig. 7.
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 nine selected observatories producing quasi-definitive data (Test (1)), 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: April 2009 (no averaging; top), January to April 2009 (middle), and May 2008 to April 2009 (down).