Short term prediction of geomagnetic secular variation with an echo
state network
Abstract
A technique for predicting the secular variation (SV) of the geomagnetic
field based on the echo state network (ESN) model is proposed. SV is
controlled by the geodynamo process in the Earth’s outer core. However,
it is difficult to model the realistic nonlinear behaviors of the
geodynamo due mainly to the very small Ekman number of the actual outer
core. This study employs the ESN to represent the temporal evolution of
the geomagnetic field on the Earth’s surface. The hindcast results of SV
demonstrate that the ESN enables us to predict SV for several years with
satisfactory accuracy. In particular, the nonlinear behaviors of SV is
accurately predicted for the case where accurate geomagnetic data with a
1-year time resolution are available. It is found that an increase in
the number of training data does not necessarily improve prediction
accuracy. The results suggest that the information on the latest
temporal variations is important for the short-term prediciton by the
ESN valid for, say 5 years.