Abstract

The radiation coming from the sun to the earth is the only form of incoming radiant energy that determines the heat balance and thermal regime of the earth. Variation of solar radiation is the single most important factor affecting the earth’s surface temperature. This study seeks to investigate the relationship between ambient temperature and soil temperature with a view to determine the existence of space-earth coupling. With a view to achieving this aim, the research was narrowed to the correlation between air temperature and soil temperature for the Nsukka area of Enugu State in Nigeria. The data used in this study was a two-year data of air temperature and soil temperature measurements collected by the Nigerian Environmental Climactic Observing Program (NECOP) station situated at Nsukka, which carried out simultaneous basic measurements of meteorological and climatological variables, in real time, through telemetry technology, with 5-min update cycles.  In order to visualize the relationship between the two variables under study, the soil and air temperatures were co-plotted with time for each month of the year for 2011 and 2012, daily and annual range using Microsoft Excel, OriginPro 2018 64-Bit and Python Programming. From the findings of this work, the air and soil temperature variation patterns over each day, month, and year depict a pattern of correlation. The soil temperature fluctuated alongside the variations observed in air temperature with the addition of time lags (response time) due to difference in their thermal conductivities and heat capacities. This time lag was observed from this work to be up to 2 to 3 h for Nsukka region. On cooling, a delay was also observed in the air temperature, as the air temperature cools about an hour after the reduction in soil temperature was observed in a daily cycle.

Key words: Solar radiation, thermal conductivity, correlation, response time, soil temperature, air temperature.