Can the Surface Quasi-Geostrophic (SQG) Theory Explain Upper Ocean Dynamics in the South Atlantic?

Autor(es)

Miracca-Lage, Mariana ; Gonzalez-Haro, Cristina ; Campagnoli Napolitano, Dante ; Isern-Fontanet, Jordi ; Simionatto Polito, Paulo

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS; v. 127, n. 2, p. 23-pg., 2022-02-01.

Resumo

Satellite altimeters provide quasi-global measurements of sea surface height, and from those the vertically integrated geostrophic velocity can be directly estimated, but not its vertical structure. This study discusses whether the mesoscale (30-400 km) dynamics of three regions in the South Atlantic can be described by the surface quasi-geostrophic (SQG) theory, both at the surface and in depth, using outputs from an ocean general circulation model. At these scales, the model surface eddy kinetic energy (EKE) spectra show slopes close to k(-5/3) (k(-3)) in winter (summer), characterizing the SQG and quasi-geostrophic (QG) turbulence regimes. We use surface density and temperature to (a) reconstruct the stream function under the SQG theory, (b) assess its capability of reproducing mesoscale motions, and (c) identify the main parameters that improve such reconstruction. For mixed layers shallower than 100 m, the changes in the mixed-layer depth contributes nine times more to the surface SQG reconstruction than the EKE, indicating the strong connection between the quality of the reconstruction and the seasonality of the mixed layer. To further explore the reconstruction vertical extension, we add the barotropic and first baroclinic QG modes to the surface solution. The SQG solutions reproduce the model density and geostrophic velocities in winter, whereas in summer, the interior QG modes prevail. Together, these solutions can improve surface correlations (>0.98) and can depict spatial patterns of mesoscale structures in both the horizontal and vertical domains. Improved spatial resolution from upcoming altimeter missions poses a motivating scenario to extend our findings into future observational studies. (AU)

• Processo FAPESP: 19/13830-8 - Como os modos baroclínicos verticais se relacionam com as ondas de Rossby observadas por satélites altimétricos?
• Beneficiário: Mariana Miracca Lage
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Mestrado
• Processo FAPESP: 19/02968-9 - Ondas de Rossby baroclínicas e a circulação de revolvimento meridional do Atlântico Sul
• Beneficiário: Mariana Miracca Lage
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 17/09659-6 - Variabilidade interanual dos transportes meridionais através da rede transatlântica SAMOC (SAMBAR)
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Temático