Diurnal and Seasonal Variations of Sensible and Latent Heat Fluxes at an Agricultural Site in Ile-Ife, Southwest Nigeria

Diurnal and seasonal variations of sensible heat (H) and latent heat (LE) fluxes observed at an agricultural site on the campus of Obafemi Awolowo University, Ile-Ife, southwest Nigeria have been reported in this paper. The deductions are made based on half-hourly flux data acquired from an open-path eddy covariance (OPEC) system measured continuously over a two-year observation period (2017-2018) at the study site. The study area is within tropical wet and dry climate of West Africa, thereby experiencing an alternating wet (that is, April – October) and dry (that is, December – February) seasons (monsoonal). Our results showed that peak hourly values of H and LE occurred at about 13:00 LT and 14:00 LT respectively, a lag of approximately one hour between them at the location. The diurnal range for H and LE during wet season was 75.3 W m^-2 and 177.0 W m^-2 respectively, while for dry season it was 182.0 W m^-2 and 89.9 W m^-2 respectively. The daily mean value of H for wet season was 19.7 ± 27.2 W m^-2 and it was 52.1 ± 63.5 W m^-2 for LE. For dry season, daily mean values for H and LE were 44.0 ± 66.4 W m^-2 and 26.6 ± 33.7 W m^-2 respectively. A transition of seasons from wet (Bowen ratio, Bo < 1) to dry (Bo > 1) was observed in November and reversal in March.

 

Keywords: Diurnal and Seasonal Variations, Sensible and Latent Heat Fluxes, Tropical Wet and Dry Climate