A Nonlinear System Science Approach to Find the Robust Solar Wind
Drivers of the Multivariate Magnetosphere
Abstract
We propose a method, based on Neural Networks, that detects the
nonlinear robust interplanetary solar wind variables, with varying
delays, driving the coupled behavior of three geomagnetic indices (Dst,
AL, and AU). As opposed to minimizing a prediction error, the method is
based on degrading the prediction by distorting the inputs of the
trained Neural Networks in order to highlight the most sensible drivers.
We show that the $z$ component of the magnetic field, the duskward
oriented electric field, and the speed of the particles of the
interplanetary medium, at particular time delays, seem to be the most
efficient drivers of the three coupled geomagnetic indices. Using only
the sensible or robust drivers in the model, we demonstrate that
iterated predictions during geomagnetic storm are significantly improved
from models that only use one of the outstanding drivers with multiple
time delays. The derived robust nonlinear Neural Network model is also a
significant improvement over linear approximations, specially when used
as iterated predictors.