Investigation of Nonlinearity Effect During Storm Time Disturbance.

We examine the nonlinearity effect in the Disturbed Storm Time (D_st ) Signals during negligible geomagnetic storm and high geomagnetic storm for monthly (January-December) D_st index time series each year from 2008-2016 using Recurrence Plot, Recurrence Quantification Analysis and Approximate Entropy. A distinct and noticeable trend between negligible geomagnetic Storm and high geomagnetic storm was observed. It was also observed that during negligible geomagnetic storm, the dynamics of the D_st signals behave in stochastic path while the increasing geomagnetic storm (high) tends to behave in deterministic path. As the influence of geomagnetic storm increases, the recurrence plot showed more deterministic structure indicating that that the recurrence plot posseses the potential to detect geomagnetic storm even at infinitesimal influence of geomagnetic storm. Also as the influence of geomagnetic storm varies, the recurrence rate also reflects the dynamical changes and its influence on determinism. From the Observed results, nonlinear dynamics is seen to perform excellently as a diagnostic model to geomagnetic storm disturbance.