This paper analyzes the sea surface height dataset from the TOPEX, Jason-1, and Jason-2 satellites of a 19-yr time series in order to extract the tide harmonic constituents for the region limited by latitude 58N-358S and longitude 558-208W. The harmonic analysis results implemented here were compared with the tidal constituents estimated by three classical tidal models [i.e., TOPEX/Poseidon Global Inverse Solution 7.2 (TPXO7.2), Global Ocean Tide 4.7 (GOT4.7), and Finite Element Solution 2102 (FES2102)] and also with those extracted from in situ measurements. The Courtier criterion was used to define the tide regimes and regionally they are classified as semidiurnal between the latitude range from approximately 58N to 228S, semidiurnal with diurnal inequality from 228 to about 298S, and mixed southward of latitude 228S. The comparison results among all tide approaches were done by analyzing the root-sum-square misfit (RSSmisfit) value. Generally, the RSSmisfit difference values are not higher than 12 cm among them in deep-water regions. On the other hand, in shallow water, all models have presented quite similar performance, and the RSSmisfit values have presented higher variance than the previous region, as expected. The major discrepancy results were particularly noted for two tide gauges located in the latitude range from 58N to 28S. The latter was investigated and conclusions have mainly pointed to the influence of the mouth of the Amazon River and the considerable distance between tide measurements and the satellite reference point, which make it quite hard to compare those results. In summary, the results have showed that all models presently generate quite reliable results for deep water; however, further study should done in order to improve them in shallow-water regions too.

ABSTRACT. A simple system for daily cloud free sea surface temperature (SST) composition based on thermal AVHRR and microwave TMI data is presented in this paper. Barnes’ objective analysis is applied as an interpolator to merge these two data sources, which have different spatial and temporal resolutions in a daily SST composition and in a regular grid product. Three comparisons were carried out as follows. First, in situ SST (daily average) measurements from eleven PIRATA’s (Prediction and Research Moored Array in the Tropical Atlantic) buoys were compared. The correlation coefficients results varied from 0.89 to 0.99, and RMSE, MAE and MBE values have not exceeded 0.57 for period from 2002 to 2010. Second, comparisons between daily SST composition and average daily in situ SST collected from twenty three drifting buoys for the period from May 2008 to October 2010. The statistics results are 0.94, 0.25, 0.19 and − 0.002 for correlation, RMSE, MAE and MBE, respectively. Third, SST (daily average) time series generated by OSTIA project was compared. The temporal and spatial RMSE (considering the study area) values ranged from approximately 0.21◦C to 1.50◦C and its average was 0.47◦C for the period from April 1st 2006 to December 31st 2010. Besides, an investigation about the influence of the data homogenization in the SST interpolation is discussed. Validation results are quite consistent (with SST composition accuracy less than 1.0◦C). Thus, aiming to fulfill the numerical oceanographic model assimilation purposes and other oceanographic features studies, the developed SST product may be recommended as a candidate.   Keywords: oceanography, objective analysis, satellites. RESUMO. Este trabalho apresenta uma metodologia para geração de composições diárias de temperatura da superfície do mar (TSM) sem contaminação de nuvens, baseada em dados termais do AVHRR e micro-ondas do TMI. A análise objetiva de Barnes é utilizada como interpolador para mesclar estas duas fontes de dados, que possuem diferentes resoluções espacias e temporais, e gerar uma composição diária de TSM em grade regular. Três tipos de comparações foram feitas com esta composição de TSM, conforme descrito a seguir. 1) Comparação com medidas in situ de TSM (média diária) de onze bóias do PIRATA. Os coeficientes de correlação variaram de 0,89 a 0,99, e os RMSE, MAE e MBE não excederam 0,57 para o período entre 2002 e 2010. 2) Comparação com medidas in situ de TSM (média diária) de vinte e três boias de deriva do PNBOIA para o período entre Maio de 2008 e Outubro de 2010. Os resultados das estatísticas foram: 0,94, 0,25, 0,19 e − 0,002 para a correlação, RMSE, MAE e MBE, respectivamente. 3) Comparação com uma série temporal de TSM gerados pelo projeto OSTIA. A faixa dos valores do RMSE (considerando a área de estudo) variou aproximadamente entre 0,21◦C e 1,50◦C e sua média foi de 0,47◦C para o período de 01 de Abril de 2006 a 31 de Dezembro de 2010. Uma investigação sobre a influência da homogeneização das diferentes fontes de dados antes do processo de interpolação é discutida. Os resultados da validação da TSM são consistentes (com uma acurácia menor que 1,0◦C).   Palavras-chave: oceanografia, análise objetiva, satélites.

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This study uses an objective analysis (OA) method to obtain more realistic data on ocean surface current estimated via Remote Sensing (RS) by OSCAR. This refinement employs surface current data estimated via drift buoys from PNBOIA. The incorporation of buoy data to OSCAR current fields was performed using an OA method based on the Gauss-Markov Theorem. The results show a slight improvement of OSCAR current fields. The interpolation allowed reducing the difference between OSCAR and buoy vectors an average of 0.0166ms -1 and 7.7892° for the intensity and direction, respectively. In a specific case, this gain came to 0.45ms -1 in intensity and 144° in direction, thus proving that the interpolation can change the current direction up to 144° and its intensity up to 0.45ms -1 , making that the value of the current measured by RS gets closer to the value measured by the buoy.