Lyapunov exponents of time series in finite amplitude electroconvection

We analyze the nonlinear time series obtained from numerical simulation of electroconvection induced by unipolar injection. These time series are non-steady and non-periodic and the dimension of the strange attractor seems to be very high. We focus our study in the computation of the maximal Lyapunov exponents, which are a measure of the divergence of two trajectories in the attractor. We have studied the evolution of the maximal Lyapunov exponent as the instability parameter varies. In all the series we found a positive maximal Lyapunov exponent, which is a strong evidence of chaos