Detecting Tropical River Plumes and Island Wakes with RADARSAT

Cresswell, GR; Tildesley, P.

doi:10.1080/07038992.2000.10874777

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…This large tidally dominated estuary contains numerous islands of different sizes and shapes, some of which are in close proximity to each other. Similar to Cresswell and Tildesley (2000)'s observation in the Sepik River plume (New Guinea), the interactions between the coastal water and the islands in the PRE can also be seen from satellite images. Focusing on the inner islands, Figure 1c illustrates vortex-like structures that emerge on the lee side of the islands.…”

Section: Introductionsupporting

confidence: 80%

Impact of Islands on Tidally Dominated River Plumes: A High‐Resolution Modeling Study

Li,

Chrysagi,

Klingbeil

et al. 2024

JGR Oceans

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When flow passes over topographic features such as headlands and islands, island wakes can arise at the lee side of the flow. Island wakes are associated with enhanced biological productivity, increased mixing, and water mass transformation. While previous studies have mainly focused on the dynamical and biological effects of island wakes in the open ocean, here we focus on a large tidally‐dominated estuary with numerous islands, aiming to investigate the impact of such wakes on the offshore transport of river plumes. To this end, we use numerical simulations with unprecedented grid resolution in the plume region and around the islands. Our study area is the Pearl River Estuary, a region where satellite images indicate that oscillating wakes occur in the lee and far downstream of the islands. We show that submesoscale island wakes are ubiquitous in the plume‐influenced region and can affect a large area around the islands as the tidal flow reverses. These strong vorticity tails correspond well with the horizontal patterns of salinity gradients and salinity mixing. Sensitivity experiments show that these flow disturbances will largely decrease after the hypothetical “removal” of the islands. Analysis based on an isohaline coordinate framework shows that the isohaline surface area is limited by the presence of islands. It is proven that this “limiting” effect of islands on the plume extension is related to the salinity mixing and the associated diahaline water exchange.

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Section: Introductionsupporting

confidence: 80%

Impact of Islands on Tidally Dominated River Plumes: A High‐Resolution Modeling Study

Li,

Chrysagi,

Klingbeil

et al. 2024

JGR Oceans

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show abstract

“…The RADARSAT images of the Long Eddy are highly consistent with the results of our drift drogue trials and our ADCP surveys and provide a ‘bird’s eye’ perspective on the development of the wake. Island wakes and other ocean eddies have been previously identified with RADARSAT images (Cresswell and Tildesley, 2000; Ivanov and Ginzburg, 2002). In the present study, the shear line of the wake is visible in all images and they reveal the surface features of the eddy at mid‐flood.…”

Section: Discussionmentioning

confidence: 99%

Flow‐field observations of a tidally driven island wake used by marine mammals in the Bay of Fundy, Canada

Johnston¹,

Read

2007

Fisheries Oceanography

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Correlations between fine-scale oceanographic features and aggregations of marine mammals are frequently reported, but the physical forces shaping these relationships are rarely explored. We conducted a series of oceanographic observations and remote sensing surveys of an oceanographic feature near Grand Manan Island known to attract marine mammals on flood tides. We tracked drift drogues from cliff-top with a theodolite and conducted boxtype surveys with an acoustic Doppler current profiler (ADCP) to assess flow patterns within the oceanographic feature. The feature was also visualized with Synthetic Aperture Radar (SAR) scenes. Drift drogues were advected towards a shear line originating near the northern tip of the island and entrained in one or more eddies downstream. ADCP surveys confirmed the presence of the shear line between rapid easterly flow and slower return flow. As the tide progressed, the shear line extended and manifested a single anti-cyclonic eddy at its distal end. As the flood tide progressed, northerly flow along the eastern shore of the island intensified and deflected the shear line northwards, shedding the eddy at slack high water. SAR images confirmed the presence of the shearline and eddy system, illustrating the evolution of a wake behind the island on flood tides. Profiles of flow direction and acoustic backscatter revealed secondary flows within the wake consistent with models and observations of other wakes. Oceanographic and remote sensing observations confirm that an island wake is generated by tidal flow past Grand Manan Island and provide an ecological context for the predictable aggregations of odontocete and mysticete cetaceans observed foraging within this region.

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New Guinea and its coastal seas, a testable model of wet tropical coastal processes: an introduction to Project TROPICS

Brunskill

2004

Continental Shelf Research

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Detecting Tropical River Plumes and Island Wakes with RADARSAT

Cited by 6 publications

References 3 publications

Impact of Islands on Tidally Dominated River Plumes: A High‐Resolution Modeling Study

Impact of Islands on Tidally Dominated River Plumes: A High‐Resolution Modeling Study

Flow‐field observations of a tidally driven island wake used by marine mammals in the Bay of Fundy, Canada

New Guinea and its coastal seas, a testable model of wet tropical coastal processes: an introduction to Project TROPICS

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