Abstract—Climate change affects ambient temperature through exchanges between the components of the soil-plant-atmosphere system. This impacts thermal comfort inside buildings, leading to heavy dependence on mechanical air conditioning. To mitigate the regulated thermal effects of the interaction of the above-mentioned system, planting trees in cities remains one of the decisive solutions. The aim of this article is to set up a numerical simulation and optimization model of soil temperature profiles in the city of Yamoussoukro (Côte d’Ivoire) under two conditions (bare surface and covered surface) to assess the impact that changes in the temperature inside the soil have on the ambient temperature. The simulation took solar energy as the natural source of heat, producing a temperature gradient at the undisturbed soil profiles. The energy source was calculated by acquiring meteorological data over two years (2017–2018), with a time step of one minute. The finite element method was used to discretize the heat equation in space, and the finite difference method was used to discretize it in time. The resulting ordinary differential equation was numerically simulated using the 4th-order Runge-Kutta method. Particle Swarm Optimization was used to find optimal temperature profiles that would have no effect on the ambiance. The equations were implemented in MATLAB R2021b software. The model was validated by measuring soil and air temperatures and relative humidity in real-life situations over two seasons using a laboratory-built data acquisition instrument. The results showed that the presence of plants in a city reduces the ambient temperature, and the predicted values agree with the measured data. In a city, when the average annual temperature of the first 20 cm of soil depth exceeds 20 °C, tree planting becomes imperative.

Keywords—Numerical simulation, soil temperature, climate variability, finite element method, Particle Swarm Optimization (PSO)

Cite: Sahi Roland Diomande, Yao N’Guessan, and Kotchi Remi N’Guessan, "Numerical Model and Optimization of the Soil Temperature Profiles in the Context of Climatic Variability in Côte D’Ivoire," International Journal of Applied Physics and Mathematics, vol. 15, no. 1, pp. 13-34, 2025.

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