Name: | Description: | Size: | Format: | |
---|---|---|---|---|
19.89 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
A presente tese apresenta uma compilação de estudos da circulação da
superficie no oceano ao largo do sudoeste da Península Ibérica, através da
combinação de dados obtidos a partir de deteção remota, observações directas
e modelação numérica. Com base nestas observações, a região oceanogrãfica
a sudoeste da Peninsula Ibérica aparece como um sistema complexo cuja circulação
ã superfície é a resposta ã acção conjunta dum campo de vento espacial/
temporalmente variãvel, ã interação da circulação costeira com o campo
de vorticidade ao largo constrangido pela existência de gradientes de pressão
ao longo da costa, e as interações desta circulação com o escoamento subsuperficial
sujeito ã batimetria do fundo. A tese tenciona descrever e discutir
a oceanografia regional descendo desde a larga escala até os processos de
mesoescala.
Os processos de larga escala mostraram uma associação dos regimes de
afloramento costeiro forçado pelo vento com o índice da Oscilação do Atlântico
Norte. A heterogeneidade espacial do campo de ventos oceânico apareceu
associada aos principais cabos, e foi proposta como principal responsável
pela geração de actividade de mesoscala. Uma parte importante desta tese
baseou-se na descrição e análise dos processos de mesoescala locais, com maior
ênfase num dos fenómenos mais desconhecidos na oceanografia regional, como
é o filamento de afloramento do Cabo de São Vicente. Quer observações
directas do filamento, quer o seu estudo com um modelo numérico mostraram
que o filamento aparece associado a um meandro do jacto de afloramento
inserido num campo povoado de vórtices persistentes com os quais mostra
interação.
The present dissertation presents a compilation of studies about the surface circulatíon off the southwestern Iberian Peninsula. These studies are based on remotely sensed data, in situ observations and numerical modelling outputs. Based on these, the oceanographic region appears as a complex system whose surface circulatíon expresses the response to a spatially and temporally variable wind field, to the interaction of coastal circulatíon with the offshore eddy field constrained by the existence of along-shore pressure gradients, all subjected to the interaction with topographically-steered sub-surface flows. The dissertation attempts to describe and discuss the regional oceanography downscaling from the large-scale down to the mesoscale processes. Large-scale processes evídenced an association with the prevailing wind-driven upwelling/downwelling regime, in close relation with the North Atlantic Oscillation index. The spatial heterogeneity of the wind field appeared related to the influence of the most outstanding capes. This was proposed as a major responsible for the generation of mesoscale activity. An important part of this dissertation was devoted to the description and analysis of local mesoscale processes. Special emphasis was put in the Cape St. Vincent upwelling filament, which is one of the most intriguing phenomena for local oceanographers. Both direct obervations and the study with a numerical model revealed that the filament occurs associated with meanders of the upwelling jet embedded in a persistent eddy field, with which interacts.
The present dissertation presents a compilation of studies about the surface circulatíon off the southwestern Iberian Peninsula. These studies are based on remotely sensed data, in situ observations and numerical modelling outputs. Based on these, the oceanographic region appears as a complex system whose surface circulatíon expresses the response to a spatially and temporally variable wind field, to the interaction of coastal circulatíon with the offshore eddy field constrained by the existence of along-shore pressure gradients, all subjected to the interaction with topographically-steered sub-surface flows. The dissertation attempts to describe and discuss the regional oceanography downscaling from the large-scale down to the mesoscale processes. Large-scale processes evídenced an association with the prevailing wind-driven upwelling/downwelling regime, in close relation with the North Atlantic Oscillation index. The spatial heterogeneity of the wind field appeared related to the influence of the most outstanding capes. This was proposed as a major responsible for the generation of mesoscale activity. An important part of this dissertation was devoted to the description and analysis of local mesoscale processes. Special emphasis was put in the Cape St. Vincent upwelling filament, which is one of the most intriguing phenomena for local oceanographers. Both direct obervations and the study with a numerical model revealed that the filament occurs associated with meanders of the upwelling jet embedded in a persistent eddy field, with which interacts.
Description
Keywords
Golfo de Cádiz Cabo de São Vicente Oceanografia física Interação atmosfera-oceano Upwelling costeiro