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| Author(s): |
Márcio Katsumi Yamashita
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC) |
| Defense date: | 2012-07-06 |
| Examining board members: |
Paulo Simionatto Polito;
Ricardo de Camargo;
Ilson Carlos Almeida da Silveira
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| Advisor: | Paulo Simionatto Polito |
| Abstract | |
Long Rossby waves are large-scale waves which propagate westward with spatial scale ranging from a few hundred to several thousand kilometers. These waves play a critical role in the adjustment of ocean circulation. Their propagation cause vertical displacements of the thermocline, often of tens meters, and cause variations of sea surface height that can be observed on satellite altimeters data. The hypothesis of this study is that there is a significant fraction of surface geostrophic velocity variability associated with westward propagating signals. To test it, we assessed the variability of the meridional geostrophic velocity at the surface induced by the passage of these waves. Digital filters are necessary to distinguish the propagating from non-propagating signals and allowed for the selection of the westward propagating component with an approximate period of about 12 months. Phase speed cp, period P, wavelength λ, mean square amplitude A and percentage of explained variance σ2 of this component were estimated where long Rossby waves from the first baroclinic mode were identified. We selected Argo profiles data positioned at different phases of the same wave to verify the influence of its propagation on temperature, salinity and density fields. The results showed that the annual Rossby wave of 237 mm height can change the density field with values up to 0.3 kg m-3 about 240 m at pycnoclin level. The explained variance of the westward meridional component of geostrophic velocity relative to the original signal revealed that 40% to 71% of the signal propagates westward, supporting the hypothesis. (AU) | |
| FAPESP's process: | 10/04454-8 - Analysis of the Vertical Influence of Long Rossby waves in the South Atlantic |
| Grantee: | Márcio Katsumi Yamashita |
| Support Opportunities: | Scholarships in Brazil - Master |