Deterministic Chaos in Precipitation and Atmospheric Temperature Time Series over North-Central Nigeria: A Recurrence Quantification Analysis Approach<b></b>

This work is focused at assessing the chaotic features in precipitation and atmospheric temperature records over North-Central Nigeria using recurrence quantification analysis. The mean daily precipitation and atmospheric temperature data for the seven states in North-Central Nigeria were collected from the Modern Era Retrospective Reanalysis (MERRA-2) spanning from 1982-2020. Recurrence plots (RP) were constructed based on the reconstitution of phase space via the method of delays while Lyapunov exponents and recurrence statistics were also computed. The results obtained show that the recurrence plots for precipitation comprise of points that are not arranged in shorter diagonal lines but form a congruent chequered pattern which is regular throughout the RP while the RPs for atmospheric temperature showed regular patterns with very short diagonal lines parallel to the line of identity (LOI) indicating chaos. The Lyapunov exponents were positive but low values (< 0.014) indication deterministic chaos while the recurrence statistics computed showed the recurrence rate of temperature has very low values (0.30-0.69 %) across all the sampled states but that of precipitation has higher values (09.83-28.24 %) as a result of its fixed seasonality. The determinism values for temperature also had lower values (0.099-0.182 %) while that of precipitation recorded higher values (75.48-88.85 %) implying more sensitive to distortions like greenhouse gases emissions from human anthropogenic activities. These results are a confirmation of deterministic chaos in the dynamics of the climate of North-Central Nigeria which is has manifested in floods, heat waves and droughts over the years.