Investigation of power law wind exponent within the lower boundary layer at Ile-Ife, Nigeria

Abstract

A sound detection and ranging (SODAR) equipment installed on the roof of a two-storey building at the Department of Physics, Obafemi Awolowo University Ile-Ife, Nigeria (7.52⁰ N and 4.52⁰ E), 294 m height above mean sea level and about 20 m above the ground level has been used to study on continuous basis the planetary boundary layer (PBL) wind. Eighteen thousand (18000) sets of hourly averaged data for the wind speed from 30 m above the surface to 500 m height at 20 m intervals had been used to study the power law wind exponent α over Ile-Ife Nigeria. The data covered about two and half years (from June 2009 to December 2011). Exponent α was found to increase with height and decrease with surface wind speed. It was also  discovered that α had both diurnal and seasonal variations. The values at daytime were lower than at nighttime and the wet months had higher values than the dry months. Its average for the dry months was 0.33 while the average for the wet months was 0.45.