Fig. 7
From: Investigation of geomagnetic reference models based on the Iridium\(^{\circledR }\) constellation
L-curve for determining the regularization parameter for the quasi-definitive observatory model. The vertical axis plots the quantity \(\sqrt{{\mathbf {g}}^{*T} \Lambda {\mathbf {g}}^{*}}\) (see text for details). The \(\lambda\) values are given in dimensionless units