Space distribution of the dates of beginning of the rainy season by means of the Technique of the harmonic analysis of a sector of the region North center of Venezuela

Abstract

ln the annual lapse the monthly totals of rain in Venezuela have diverse causes among which is neccesary to mention to the waves of the East, the tropical storms, the masses of air coming from occluded cold fronts and the due one to processes convective and the Intertropical Convergence (ITC), being this last one the main origin of the rainy season in Venezuela. Since the curve or graph of the monthly distribution of the rain, in the annual, reflective lapse jointly the effect of all those meteorological phenomenons, is not possible to define accurately when the ITC is presented (which becomes present only in a part of the year) and, therefore, to point out the possible beginning of the rainy season, moment that could be used to plan that human activity related with this pluvial process. However, by means of the technique of the Harmonic Analysis, based on the the trigonometrical series of Fourier, it coluld be carried out a mathematical separation of the contribution that cause the factors mentioned on the rain in their annual course, enhancing in way peculiar to the fraction coming from the ITC. The application of the harmonic analysis at 102 pluviometric stations on a sector of the Region North Center of Venezuela it allowed to obtain the temporary distribution of the rain in each measurement point, information that allowed to identify the following temporary distribution of the beginning of the rains basically the ITC: 65 in May, 18 in June, 10 in July, 3 in August and 6 in September. With base to parameters of the series of Fourier, and by means of the interpolation technique Kriging, the cartographic representation of the isochronous of the maximum of the rainy season was elaborated caused by the ITC, isolines that facilitate to model spacely, and in a coninuous way, to the pluvial process, that which allows to estimate, on the average, the beginning of the rainy season in any place of the area in study.