Periodicity of downward longwave radiation at an equatorial location
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Date
2019
Authors
Obot, N. I.
Humphrey, I.
Chendo, M. A. C.
Oyeyemi, E.O.
Udo, S.O.
Journal Title
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Abstract
Abstract
A good understanding of the diverse mechanisms in the atmosphere is required in modelling the
climate. In this study, the diurnal and seasonal patterns of all-sky downward longwave radiation
(DLR) at Ilorin (8o 32l N, 4o 34l E), Nigeria were investigated alongside relative humidity (RH)
and temperature. The average diurnal pattern of DLR gives an arc that begins by increasing
gradually with some inherent fluctuations from 01:00 hour to a maximum at 14:00 hour local time,
and then gradually decreases to a minimum at 00:00 hour. However, sometimes erratic and double
peak arc diurnal DLR patterns occur around the mid and the end of the year periods respectively.
The seasonal, diurnal peak of temperature and the minimum of relative humidity (RH) occur
approximately two hours after the peak of DLR. Besides, the seasonal trends of both DLR and RH
match each other, except sometimes in June, which could be due to the midyear DLR erratic
diurnal effect. Possibly, the mechanisms of the inter-tropical discontinuity (ITD) influence the
particular diurnal patterns of DLR at the midyear and year-end periods. Moreover, monthly
dispersion of DLR is high during known months of high atmospheric aerosols, and annual
maximum temperature occurs after the Harmattan season. Hence, variations in DLR are influenced
mostly by mineral dust in the atmosphere, mechanisms of ITD and changes in the sun-earth
distance, which reflects on the different seasons in Ilorin.
Description
Keywords
Downward longwave radiation (DLR); Temperature; Relative humidity; Intertropical discontinuity (ITD); Sun-earth distance
Citation
8. Obot N.I., Humphrey I., Chendo M.A.C., Oyeyemi E.O. and Udo S.O. (2019). Periodicity of downward longwave radiation at an equatorial location. Journal of Earth and Space Physics 44, (4), 165–177.