Investigation of Turbulent Tidal Flow in a Coral Reef Channel Using Multi-Look WorldView-2 Satellite Imagery

Abstract

The general topic here is the application of high-resolution satellite imagery to the study of ocean phenomena having horizontal length scales of several meters to a few kilometers. The present study investigates whether multiple images acquired quite closely in time can be used to derive a spatial map of the surface current in situations where the near-surface hydrodynamics are dominated by bed-generated turbulence and associated wave–current interaction. The approach is illustrated using imagery of turbulent tidal flow in a channel through the outer part of the Great Barrier Reef. The main result is that currents derived from the imagery are found to reach speeds of nearly 4 m/s during a flooding tide—three times larger than published values for other parts of the Reef. These new findings may have some impact on our understanding of the transport of tracers and particles over the shelf.

Selective foraging behavior of seabirds in small‐scale slicks

“…UAVs provide a bird's eye, rather than oblique, view on seabird movement and underlying flows (Lieber et al 2021) and thus provide a suitable tool to quantify slick interactions. Satellite remote sensing can now capture near-surface oceanographic features of length-scales ranging from kilometers to several meters (Marmorino 2022), such as slick lines (Gade et al 2013), but cannot track seabird movements. Therefore, UAVs are a bio-physical remote sensing tool which can address these blind spots, providing on-demand, high-resolution data at relatively low costs (Gray et al 2022).…”

A First Look at Internal Waves in the Great Barrier Reef Lagoon

“…On many continental shelf areas, internal waves are generated through a direct interaction of tidal currents with shelf break and then freely propagate across the shelf [5]. But as a source of internal waves in the lagoon, the shelf break can be excluded as an impossibility, as flow through the dense reef complex is turbulent throughout the water column [6]; hence, there is no stratification to support internal waves.…”