%0 Journal Article
%T Remote wind stress influence on mean sea level in a subtropical coastal region
%A Mabel Calim Costa
%A Marcos Eduardo Cordeiro Bernardes
%J Brazilian Journal of Oceanography
%D 2012
%I Universidade de S?o Paulo
%R 10.1590/s1679-87592012000300006
%X The purpose of this study was to assess the relative influence of remote wind stress on mean sea level (MSL) variations in the coastal region of Cananeia (Sao Paulo State, Southern Brazil) during the period from 1/1/1955 to 12/31/1993. An optimized low-pass Thompson filter for the study area, and spectral analysis (cross spectrum, coherence and phase lag) of the relationship between the MSL and both parallel (T//) and perpendicular (T|) wind stress components were applied. These were extracted from four grid points of the NCEP/NCAR global model. The predominance of annual oscillations as those of greatest coherence and energy, of periods of approximately 341 days (frequency of 0.00293 cpd) and 410 days (frequency of 0.00244 cpd), respectively, were observed. Offshore NCEP/NCAR grid points were those with the highest coherence and energy throughout the study in relation to the observed MSL. This may be linked to the restriction of the NCEP/NCAR model as regards the inland limit. It is also concluded that remote wind stress may play an important role in several MSL time scales, including the annual ones. Based on criteria such as coherence and energy peaks, the wind stress component of greatest effect on MSL was the parallel one. O presente estudo tem por objetivo avaliar a influ¨ºncia relativa de tens o do vento remoto na varia  o do n¨ªvel m¨¦dio do mar (NMM) para a regi o costeira de Canan¨¦ia (SP) durante o per¨ªodo de 1/1/1955 a 31/12/1993. Foram aplicados um filtro de passa-baixa de Thompson (1983), otimizado para a regi o de Canan¨¦ia, al¨¦m de an¨¢lise espectral (espectro cruzado, coer¨ºncia e defasagem) entre o NMM e as componentes paralela (T//) e perpendicular (T|) da tens o do vento. Estas foram extra¨ªdas de quatro pontos de grade do modelo global NCEP/NCAR. Observou-se a predominancia das oscila  es anuais como aquelas de maior coer¨ºncia e energia, destacando-se os per¨ªodos de aproximadamente 341 dias (frequ¨ºncia de 0,00293 cpd) e 410 dias (frequ¨ºncia de 0,00244 cpd), respectivamente. As maiores coer¨ºncias e energia em todo estudo foram encontradas nos pontos mais distantes da costa. Este fato pode estar associado ¨¤s restri  es do modelo NCEP/NCAR em representar os limites continentais. Conclui-se tamb¨¦m que a tens o do vento remoto pode ter um papel importante em v¨¢rias escalas temporais do NMM, incluindo a escala anual. A partir dos valores de coer¨ºncia e picos energ¨¦ticos, a componente paralela da tens o do vento foi a que mostrou ser mais influente no NMM da regi o estudada.
%K Filtro de Thompson
%K An¨¢lise espectral
%K NCEP
%K Canan¨¦ia
%K Brasil
%K Thompson filter
%K Spectral analysis
%K NCEP
%K Cananeia
%K Brazil
%U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592012000300006