Variations of surface temparature with solar activity at two stations in the tropics

Abstract

The response of surface air temperature to solar activity has been investigated at a tropical region, Ibadan (7.43°N, 3.90°E) and Ikeja (6.55°N, 3.35°E), during the solar cycle #22 (1987-1996). A consistent and persistent diurnal variation in surface air temperature exists which shows an almost constant level in the early morning hours (0000 0600 hours LT.); a rise at sunrise till about 1500 hr LT., a subsequent fall to the constant level by about 1900 hr LT. at sunset. This is explicable in terms of tropospheric heating mechanisms in response to solar activity. The observed diurnal variation has consistent post-noon maximum at about 1500hr LT and is asymmetric about the maximum. The post local noon maximum may be due to the modulation of the solar effects by the tropospheric constituents capable of absorbing the transient radiant heat from the Sun through the upper atmosphere. Slight negative correlation (-0.4175, Ibadan and -0.2628, Ikeja) exists between the surface air temperature and solar activity at all time levels, which imply that the temperature increases with declining solar activity. Polynomial functions may be more suitable to model the relationship between the surface air temperature and solar activity. Keywords : surface air temperature, solar activity, post-noon, tropospheric heating Nigeria Journal of Pure and Applied Physics Vol. 4(1) 2005: 25-31