ИСТИНА

Remote reference method is widely used in magnetotelluric investigations, however limits of this method are not studied properly. Large amounts of data are analyzed in this investigation and average coherence between magnetotelluric fields is estimated depending on distance between sites, frequency range and latitude of observation. Efficiency criterion for remote reference method is proposed and maximal distances are estimated. Remote reference can be placed on distance a few hundred kilometers in high latitudes and one thousand kilometers in middle latitudes.