Estimation of Atmospheric Turbidity Parameters in Ile-Ife, Nigeria

Abstract

This study estimated the levels of atmospheric turbidity in Ile-Ife, a tropical location in the Southwest of Nigeria, from November, 2017 to March, 2019. This was with the aim to quantify the degree of atmospheric cleanliness of the study location. The methods of estimation used are: the Angstrom turbidity parameters (α and β), Linke turbidity factor (TL) and horizontal visibility (VH). The values of α and β range between 0.6 and 1.4; 0.10 and 0.91 respectively. The values obtained for TL varied between 1 and 7 while visibility values ranged between 2 and 14 km. Maximum values of β and TL (corresponding to low values of VH) were obtained in the dry season (particularly in the months of January and February) while the lowest values of the same methods of estimation (corresponding to high values of VH) were recorded in the wet season (specifically in August and September). The elevated turbidity observed in the dry season was linked to episodes of Harmattan dust storms usually experienced at the study location. The study concluded that a polluted atmosphere dominates the study location especially in the dry season as indicated by the different atmospheric turbidity parameters.

Eddy Covariance Measurements of Turbulent Heat Fluxes over a Grass-covered Surface in a Tropical Location

“…As the dry season continued, H s gradually decreased to 178.5 Wm -2 in February and 146.9 Wm -2 in March. The wet season commenced in April and the daytime maximum value of H s observed was 105.7 Wm August has been known to be the cloudiest month throughout the year at the study location [33]. The frequent occurrence of clouds experienced at this period impedes the incoming solar radiation, hence low irradiance.…”

“…The monthly minimum average values obtained for solar radiation (125 Wm 260 C) were recorded in August. August is characterized by the 'short dry period' in the wet season and lasts for about three weeks [33]. This month has the cloudiest weather throughout the year, resulting in low irradiance and consequently, low air, surface and soil temperatures.…”

Evaluation of Selected Empirical Schemes of Calculating Sensible Heat Flux from Routinely-Measured Meteorological Parameters in a Tropical Location

“…The monthly minimum average values obtained for solar radiation (125 Wm were recorded in August. This result can be explained by the fact that August represents the 'short dry period' in the wet season and lasts for about three weeks [26]. This month experiences the cloudiest weather throughout the year, resulting in low irradiance and consequently, low air, surface and soil temperatures.…”