Fractal analysis of the solar wind flow in the inner heliosphere

We argue that the inner heliosphere is a chaotic system. We invoke time series analysis of the measurements by the Hellos spacecraft (near the Sun) in low-speed streams. The slope of the calculated correlation function saturates at some finite value of the embedding dimension, indicating a low-dimension of the attractor of about 3.5. Furthermore, the largest calculated positive Lyapunov exponent of similar to 1/5 bits per data sample (40.5 s) shows sensitive dependence on initial conditions. This means that the predictability of the system is limited to about 1 h. (C) 1997 Elsevier Science Ltd.