Detectability of decadal variations of the surface electric potential generated by zonal oscillating flows in Earth's core

Electric voltage measurements using long submarine cables have been performed with one of the purposes to obtain the strength of the toroidal field and its variation at the core-mantle boundary. Several observational constraints on the toroidal field have been obtained but the physical plausibility of them was examined. We performed a simple but systematic computation of kinematic dynamo surrounded by electrically conducting mantle in order to examine the plausibility. It is confirmed that the dynamo can generate the strength of the toroidal field variation obtained observationally naturally. Detectability of the electric signal originated from the geodynamo against those from magnetotelluric or motional induced electric field is re-examined. Understanding of the decadal variation of the ocean flow is indispensable for the detailed discussion of the toroidal field using submarine cable voltages.