Effects of Zeros in Phase Space Reconstruction for Small and Large Solar Radiation Data Points during Wet and Dry Seasonal Modeling and Prediction

Abstract

The effect of zeros in the behaviour of nature system has been a major global concern which have been reported to bias the output of the analysis. This study examines the effect of zeros on small and large solar radiation data points in Nsukka from a nonlinear dynamic perspective. The solar radiation data used were collected from National Research for Space and Development Agency (NARSDA) and covers the period of two years (January 2012–December 2013). The influence of zeros on average mutual information method for delay time (?), False nearest neighbour (FNN) for embedding dimension (?), and phase space reconstruction is investigated by considering two different cases (one hour and five minutes interval for small and large data points on monthly basis respectively). The results reveal that the phase space trajectories of the raw and non-zero small data points for dry and wet seasons show evidence of an attractor
in a well-defined region while raw and non-zero large data points have no attractor like shape but regular patterns and well-defined shapes are visible in dry and wet seasons. These imply low-dimensional and deterministic chaotic nature of the underlying dynamics of raw and non-zero data for small and large data points during wet and dry seasons. It is observed that there is little or no significant difference in the phase space reconstruction of raw and non-zero data for both small and large data points due to the low percentage of zeros in the time series data.

Keywords: mutual information method, Phase space reconstruction, False nearest neighbour, chaotic nature.