Internal Waves in the Andaman Sea

Abstract

The Andaman Sea of the Indian Ocean is one of the sites in the World’s ocean where extraordinarily large internal waves are encountered. For centuries, seafarers have noticed in the Andaman Sea often bands of strongly increases sea surface roughness extending from horizon to horizon. Now we know that they are sea surface manifestations of large amplitude internal waves (LAIWs), which are waves in the interior of the ocean. They can exist when the water body is stratified, i.e., when the water body consists of layers of different density. The LAIWs in the Andaman Sea are nonlinear waves which are generated by tidal flow over shallow bottom topography, like shallow ridges or sea mounts. Synthetic aperture radar (SAR) images have been very instrumental in studying the generation and propagation of internal waves in the Andaman Sea. The predominantly eastward propagating internal waves finally shoal on the shelf at the west coast the Malay Peninsula, where they usually break and generate turbulence. This causes transport of nutrient-rich water from deeper water layers to near-surface layers and gives rise to increased plankton growth. The LAIWs are associated with strong currents at depths and are a potential threat to oil drilling operations at sea.