CLIMATOLOGY OF SURFACE LAYER TEMPERATURE INVERSIONS AND ATMOSPHERIC STABILITY IN AKURE CITY CENTRE, NIGERIA

Abstract

This study investigates the characteristics of surface layer temperature inversions and atmospheric stability in Akure City Centre. Atmospheric temperature profile and wind speed were measured for both wet and dry seasons, June 2013 and July 2013 were considered for the wet season while December 2013 was considered for the dry season. A telecommunication mast beside the Akure central mosque, Oja-Oba (Oba’s Ultra-Modern Market), Akure was instrumented with shielded Maxim Integrated iButtonthermochrone temperature sensors and loggers at four levels 10m, 17m, 30m and 47 m heights. Air temperature data were logged at 15 minute intervals by the sensors. The wind speed was measured at 4m and 10m on a lamppost in the middle of the road using RM Young wind sentry connected to a Campbell Scientific CR200 data logger powered by a 12V rechargeable battery and solar panel. The data were then analyzed using descriptive statistics. Results showed that atmospheric stability was dominantly neutral followed by very stable (inversion) conditions with a few occurrences of unstable conditions in June. July is dominated by neutral conditions with unstable conditions predominant between the hours of 8a.m. and 5p.m. with few occurrences of very stable conditions. There was no significant occurrence of inversions in December; it is characterized dominantly by unstable conditions with few occurrences of neutral conditions. Based on the above results, only the wet season recorded periods with inversions. This could be due to the high frequency of overcast conditions during these periods. For the two months that recorded inversions, the mid-day inversions period were the strongest, followed by the evening period and then the morning period. Higher resolution measurements (1-5 minute averages) will be required in future studies to fully understand the behavior of inversions in Akure.