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Mauder, Matthias ; Jegede, Oluwagbemiga O. ; Okogbue, E. C. ; Wimmer, Florian ; Foken, Thomas:
Surface energy balance measurements at a tropical site in West Africa during the transition from dry to wet season.
In: Theoretical and Applied Climatology.
Bd. 89
(2007)
Heft 3-4
.
- S. 171-183.
ISSN 1434-4483
DOI: https://doi.org/10.1007/s00704-006-0252-6
Abstract
In one of the first micrometeorological experiments at a tropical site in West Africa, direct measurements of all surface energy balance components were carried out. The experiment NIMEX-1 in Ile-Ife, Nigeria (7°33’N, 4°33’E), was conducted from February 19, 2004 to March 9, 2004, during the transition from the dry to the wet season. Three typical weather situations could be observed: firstly, monsoonal winds from southwest blew over desiccated soils. Almost 100% of the available energy at the surface was transformed into the sensible heat flux. Secondly, after several thundershowers, monsoonal winds swept over soils of increased water content, which led to a partitioning of the available energy corresponding to Bowen ratios between 0.3 and 0.5. Thirdly, harmattan winds advected dry dusty air from northern directions, which reduced the incoming shortwave radiation. Again, Bowen ratios range from 0.3 and 0.5 during daytime, whereas latent heat fluxes are still high during nighttime due to advection of very dry air. No systematic unclosure of the surface energy balance could be found for the NIMEX-1 dataset. Unlike other experiments in Europe, most of the ogives for the sensible and latent heat flux were found to be convergent during NIMEX-1 in Ile-Ife. This can be attributed to the homogeneity of the surrounding bush, which lacks the defined borders found in agriculturally cultivated landscapes.