Estudo da variabilidade na distribuição espectral das ondas de Rossby baroclínicas no Atlântico e em particular na região do arquipélago de Abrolhos

Fifteen years of sea surface height anomaly (SSHA) from merged TOPEX/Poseidon and Jason-1 datasets gridded using an autocorrelation-based interpolation method are used to test the spectral variability of first mode baroclinic Rossby waves in the Atlantic Ocean. The gridding method is innovative and was specifically developed for this purpose. Mean SSHA, trends and monthly climatologies were determined globally. The global SSHA trends show regions of rising sea level of more than 10 mm  yr −1 and some regions of sinking the same order of magnitude. A two-dimentional wavelet analisys-based methodology was entirely developed for the purpose of  this study and is unprecedently applied to the altimetry data. SSHA longitude-time diagrams are filtered through the two dimentional wavelet filter and decomposed to  obtain at certain latitudes the variation of the seasonal cycle and of the propagating signal linked to these waves. The methodology is first applied to the Pacific  Ocean at 28, 5 ◦ N to validate the results with the available literature and then applied to the Atlantic Ocean with detail at the latitudes 32, 5 ◦ N and 17, 5 ◦ S. The  calculated phase velocities for the Atlantic range from −20 km day −1 at 10 ◦ latitude to −2 km day −1 at 38 ◦ latitude. The spectral variability of Rossby waves is analysed at three locations: 28, 5 ◦ N 134, 3 ◦ E, 32, 5 ◦ N 73, 5 ◦ W and 17, 5 ◦ S 35, 2 ◦ E. In all cases spectral change is observed in time, at the annual, semi-annual and  quarterly spectral bands both in intensity and in persistence. Furthermore, through the longitude-time spectral power distribution analysis in various spectral bands,  there is spatial variability in the Rossby wave spectrum.

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