Using TNT-NN to unlock the fast full spatial inversion of large magnetic microscopy data sets

Earth, Planets and Space

Table 2 Summary of the unidirectional basalt inversion parameters and results

Method	P	\(\theta\) (\(^\circ\))	\(\phi\) (\(^{\circ }\))	m (Am\(^2\))	Residual RMS (nT)
lsqlin piecewise	25976	0	0	\(1.6\times 10^{-6}\)	1140
lsqlin	25976	0	0	\(2.7 \times 10^{-6}\)	75.8
TNT-NN	25976	0	0	\(2.7\times 10^{-6}\)	27.3
TNT-NN	47500	0	0	\(3.1\times 10^{-6}\)	16.2
Fourier	200000	0	0	\(2.5\times 10^{-6}\)	685
2G	–	\(0 \pm 1\)	\(0 \pm 1\)	\(2.2 \times 10^{-6}\)	–

The first column shows the method used to obtain results: the numerical method or a 2G Enterprises Superconducting Rock Magnetometer (2G, shown in the final row). The second column, P, is the number of sample points collected by the scanning SQUID microscope. We set the number of dipoles, equal to the number of samples for each inversion. The third and fourth columns give the unidirectional orientation of the dipoles as used for NNLS analysis. The fifth column lists the moment, m. The final column provides the residual RMS of the NNLS fits with the B\(_z\) field. 2G data were obtained from Weiss et al. (2007b)