Statistics of atmospheric surface layer turbulence over a tropical region: a case study of Ile-Ife, Nigeria

In this study, an attempt was made to investigate the variation of surface layer turbulent heat fluxes and turbulence statistics at Obafemi Awolowo University Teaching and Research Farm (OAUTRF) for a period of 3 months (May–July) in 2018 using an eddy covariance (EC) system comprising of three-axial sonic anemometer (CSAT3) and Infrared gas analyzer (LI-7500A) placed side by side with temperature–humidity sensor (HMP45C). The EC and gas analyzer measures the fluctuations of the wind and vapor (water and CO 2 ), respectively, while the temperature–humidity sensor was used to measure ambient temperature and relative humidity. The results showed that the sensible and latent heat fluxes increase as the sun rises due to the evolution of turbulence as a result of an increase in solar heating. In addition, the latent heat fluxes were observed to be greater than the sensible heat fluxes due to soil wetness caused by rainstorm events which enhance evaporation processes during this period. The month of May recorded the highest values of 0.22 m / s , 2.31 m / s , and 0.19 for friction velocity, mean wind speed, and vertical velocity, respectively, due to the strong vertical convection. The mean turbulence intensities of crosswind, along-wind, and vertical wind are 0.57 , 0.50 , and 0.19 , respectively, with I v > I u > I w . The turbulent intensity along the three wind components decreases rapidly with increasing wind speed due to the dominance of the thermal-induced turbulence during the observational period. Turbulent kinetic energy (TKE) was noticed to be very low (0.02–1.40) due to the low wind speed that characterized the humid tropical environment. The study generated turbulent data and provided unprecedented insight into turbulent characteristics in the lower atmosphere around a tropical region. This can aid in the study of land-surface processes and climate change.