Análise do nível da água na plataforma continental setentrional do Nordeste do Brasil

Abstract

The objective of this work is characterize the sea level on the continental shelf of Ceará, using harmonic analysis, morphometric variability and wavelet analysis. The data was recorded by tide gauge located in Porto do Mucuripe during the period from 2009 to 2011. Tide data from Santana, Salvador and Imbituba station, for the year 2009 were also used. Meteorological data were obtained from Campus do Pici - UFC. The morphometric variability showed that the tides reached maximum values during periods of equinox. The minimun values were registered during solstice period. There is also variability between consecutive neap tide and spring tide, reaching differences of more than half a meter. Fifty-nine harmonic constituents were determined, and it was possible to characterize the tide regime as semi-diurnal, with an Form Number of 0,11. The harmonic constituent S2 had higher annual growth of 0,22 m, determining the oscillating of Form Number Anomaly. The anomaly presented minimum values in March and September, due to the higher intensity of semi-diurnal component, and maximum in June and December, showing a decline of semi-diurnal component. The wavelet analysis of the data showed that low-frequency wind is not associated with fluctuations in sea level on the Ceará coast. These effects may be related to remote wind tension. The power spectra and coherence of the tide levels showed a medium to high correlation between stations Fortaleza-Santana. There was no correlation between Fortaleza-Salvador and Fortaleza-Imbituba stations, indicating that possible platform waves did not move toward the northern coast of Brazil during the analyzed period.