Fig. 1From: Spatial gradients of geomagnetic temporal variations causing the instability of inter-station transfer functionsModel of MC-NMF. \(F\), \(T\), and \(K\) denote number of frequencies, time windows, and Basis vectors, respectively. \(\varvec{X}\) denotes observed spectrograms, \(\varvec{B}\) denotes Basis vectors, and \(\varvec{U}\) denotes ActivationsBack to article page