An Empirical Formulation of an ITD Rainfall Model for the Tropics: A Case Study of Nigeria

Abstract

An attempt is made in this paper to examine Nigerian rainfall patterns within the framework of the dominant influence of the Intertropical Discontinuity (ITD), defined here as a moisture boundary separating dry northern air from moist southern air. The characteristics of this moisture boundary are discussed with respect to its influence on the distribution patterns of rainfall. The dynamic factors affecting the rainfall are then synthesized into an ITD plus coastal rainfall model but with an implicit recognition of the modifying effects of such terrain features as the windward, leeward, and valley locations of stations and elevation. The model is shown to have some predictive value, particularly in Nigeria and adjacent territory. Abstract An attempt is made in this paper to examine Nigerian rainfall patterns within the framework of the dominant influence of the Intertropical Discontinuity (ITD), defined here as a moisture boundary separating dry northern air from moist southern air. The characteristics of this moisture boundary are discussed with respect to its influence on the distribution patterns of rainfall. The dynamic factors affecting the rainfall are then synthesized into an ITD plus coastal rainfall model but with an implicit recognition of the modifying effects of such terrain features as the windward, leeward, and valley locations of stations and elevation. The model is shown to have some predictive value, particularly in Nigeria and adjacent territory.