Estudo das correntes costeiras nas proximidades do canal de navegação do porto de Fortaleza, Ceará, Brasil

Abstract

This study evaluates the temporal variability of currents nearby to the navigation channel of the Port of Fortaleza, investigating the influence of astronomical, highfrequency and sub-tidal components of the currents. Magnitude and direction data of the currents were obtained with a moored SonTek® Acoustic Doppler Current Profiler (ADCP) near the isobath of 15 m for the period between January 10 and February 27 of 2015. Wind data were obtained for the same period at a weather station located at Castelão neighborhood in Fortaleza, Ceará. The current was initially broken down into its along-shelf (U) and cross-shelf (V) components. The harmonic components (Uh and Vh) were decomposed by harmonic analysis. The high-frequency components (Uaf and Vaf) were selected by filtering. The sub-tidal (Uv and Vv) were obtained by subtraction of harmonic and high-frequency components. The energy of the components was quantified by variance analysis. The results are Uh and Vh, 63,7 and 62,8%; Uaf and Vaf, 18,1 e 24,7%; Uv e Vv, 18,2 e 12,5%, respectively. Therefore, according to the analysis performed for the study during this period, the astronomical components, including the continual action of the wind, are primary agents of the changes that happen in the hydrodynamic phenomena nearby to the navigation channel of the Port of Fortaleza. So, both Uh and Vh components of the tidal current have the majority influence in the circulation of water in this region, in other words, the circulation is caused mainly by the tidal currents, quantitatively, and winds, qualitatively.