Multifractal analysis of air and soil temperatures

Air and soil temperatures are important agrometeorological variables with several applications. Understanding the complex behavior of air and soil temperatures, as well as their interaction, will help in agricultural planning. Multifractal detrended fluctuation and multifractal cross-correlation analysis of air and soil temperatures were carried out in three locations (Akure, Abuja, and Bauchi) within a tropical country, Nigeria. Monthly and annual air and soil temperatures measured at 5 min intervals for a period of 1 year were obtained and analyzed for multifractality. There is evidence of seasonal dependence in the multifractal behavior of monthly soil temperature. Monthly temperatures (air and soil) were found to have higher degrees of multifractality than annual temperatures. Furthermore, latitudinal dependence was observed in the multifractal behavior of air and soil temperatures. The cross-correlation between air and soil temperatures also shows multifractality with persistence at the monthly scale and anti-persistence at the annual scale. This work has shed light on the complex relationship between air and soil temperatures, and the results will be useful in modeling the two variables.