Root mean square of residuals between all input satellite vector data and parent model. Lines show X, Y, and Z component residuals plotted against geomagnetic dipole latitude. Northern hemisphere summer is defined as spring through autumn equinox, northern hemisphere winter as autumn through spring-equinox. The RMS values are calculated over 3° wide latitude bands. Note that the drop in residuals between ±50° is due to local time selection at those latitudes.