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Summary of Proposal OCE3205

TitleMultimodal Internal waves observed with TerraSAR-X
Investigator da Silva, Jose - University of Porto, Geosciences, Environment and Spatial Planning
Team Member
Dr. Magalhaes, Jorge - University of Porto, Interdisciplinary Centre of Marine and Environmental Resea, Department of Geosciences, Environment and Spatial Planning
Professor Garcia, Carlos - Federal University of Rio Grande, Physics Department
Professor Wang , Caixia - Ocean University of China, Department of Oceanography
SummaryThe multimodal evolution of nonlinear internal waves into shorter scales can be successfully observed in satellite SAR images, and is the subject of the present proposal. The turbulence they produce when they break is a vital aspect of the ocean's meridional overturning circulation and hence it has been a major motivation for studying them. SARs can provide unique insight into the observation on Internal Solitary Waves (ISWs), particularly during their shoaling and antishoaling processes across steep variable bathymetry. By shoaling (antishoaling) we mean the propagation of a well-defined solitary-like wave over monotonically decreasing (increasing) depths across steep bottom slopes, usually a continental shelf-break or a steep ocean ridge. There is a resonant coupling between large (i.e. with length scales of about 20 km) mode-2 long lived solitary-like waves and short (i.e. with length scales of about 1 km) mode-1 ISWs, which can be observed in SAR images (da Silva et al., 2015). In this proposal we plan to investigate the multimodal evolution of solitary-like waves at a few locations where this phenomenon is expected: Amazon shelf break (South America), Mozambique Channel (Africa), Andaman Sea (Indonesia) and the South China Sea (Indian Ocean), where we know that steep bottom slopes are found close to strong ISW generation sites. The region of excellence is the Amazon shelf break, where we plan also to investigate the interaction of low-mode internal tides generated at the shelf break and propagating into the open ocean with eddies and the meandering field of steady currents such as the North Brazil Current (NBC) and the North Equatorial Counter Current (NECC). This is challenging because the ISWs are observable in the SAR, but the ITs are not. The current and eddie fields will be observed with Altimeter products (such as AVISO) and the internal tide generation is predictable (e.g. Baines, 1982 model). In addition, we plan to study the seasonal variability and longevity of some newly discovered short-period ISWs over the shelf off the Amazon River mouth (discovered in the frame of TerraSAR-X project OCE2254). The PI is a world leader in SAR observations of internal waves, and is funded by the Portuguese Foundation of Science and Technology (FCT) under the “plurianual” scheme of the Interdisciplinary Centre of Marine and Environmental Research CIIMAR and the group of Coastal and Ocean Dynamics (COD), which benefits from high performance computational resources. The PI is also partly funded by a Brazilian project (PVE 313603/2013-8) titled “Internal wave systems in the tropical and western South Atlantic: from satellite views to local predictability” whose total budget is 85K euro, with funds specifically itemized for image acquisition. Post-doc Magalhaes is funded by FCT under a scholarship (SFRH/BPD/84420/2012).

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